Obstentrics_Williams

Obstentrics_Williams. Bladder Dysfunction. With neuraxial analgesia, bladder sensa tion is likely to be obtunded and bladder emptying impaired for several hours after delivery. As a consequence, bladder distention is a frequent postpartum complication, especially if appreciable volumes of intravenous luid are given. Millet and colleagues (2012) randomized 146 women with neuraxial analgesia to either intermittent or continuous bladder catheterizations and found that the intermittent method was associated with signiicantly higher rates of bacteriuria. That said, we do not recommend routine postpartum use of indwelling catheters following uncomplicated vaginal delivery. Arachnoiditis and Meningitis. Local anesthetics are no longer preserved in alcohol, formalin, or other toxic solutes, TABLE 25-6. Absolute Contraindications to Neuraxial Analgesia


Obstentrics_Williams

Obstentrics_Williams. Arachnoiditis and Meningitis. Local anesthetics are no longer preserved in alcohol, formalin, or other toxic solutes, TABLE 25-6. Absolute Contraindications to Neuraxial Analgesia Skin infection over site of needle placement and disposable equipment is usually used. hese practices, coupled with aseptic technique, have made meningitis and arachnoiditis rare (Centers for Disease Control and Prevention, 2010). Contraindications to Neuraxial AnalgeSia Shown in Table 25-6 are absolute contraindications. Obstetrical complications that are associated with maternal hypovolemia and hypotension-for example, severe hemorrhage-are contraindications (Kennedy, 1968).


Obstentrics_Williams

Obstentrics_Williams. Disorders of coagulation and defective hemostasis also preclude neuraxial analgesia use. Although no randomized studies guide the management of anticoagulation at the time of delivery, consensus opinion suggests that women given subcutaneous unfractionated heparin or low-molecular-weight heparin should be instructed to stop therapy when labor begins (Krivak, 2007). Subarachnoid puncture is also contraindicated if cellulitis involves the planned needle entry site. Many consider neurological disorders to be a contraindication, if for no other reason than that exacerbation of the neurological disease might be erroneously attributed to the anesthetic agent. Other maternal conditions, such as aortic stenosis or pulmonary hypertension, are also relative contraindications (Chap. 49, p.i948).


Obstentrics_Williams

Obstentrics_Williams. Severe preeclampsia is another comorbid condition in which markedly decreased blood pressure can be predicted when neuraxial analgesia is used. Wallace and associates (1995) randomly assigned 80 women with severe preeclampsia undergoing cesarean delivery at Parkland Hospital to receive general anesthesia or either epidural or combined spinal-epidural analgesia. Maternal and neonatal outcomes did not difer. Still, 30 percent of women given epidural analgesia and 22 percent of those given spinal-epidural blockade developed hypotension. he average reduction in mean arterial pressure ranges between 15 and 25 percent.


Obstentrics_Williams

Obstentrics_Williams. Relief of labor and childbirth pain, including cesarean delivery, can be accomplished by injection of a local anesthetic agent into the epidural or peridural space 25-3). his potential space contains areolar tissue, fat, lymphatics, and the internal vertebral venous plexus. This plexus becomes engorged during pregnancy such that the volume of the epidural space is appreciably reduced. Entry for obstetrical analgesia is usually through a lumbar intervertebral space. Although only Spinal needle punctures the dura mater for injection 1 I: FIGURE 25-3 Neuraxial analgesia: A. Combined spinal-epidural analgesia. B. Epidural analgesia.


Obstentrics_Williams

Obstentrics_Williams. Spinal needle punctures the dura mater for injection 1 I: FIGURE 25-3 Neuraxial analgesia: A. Combined spinal-epidural analgesia. B. Epidural analgesia. one injection may be elected, usually an indwelling catheter is placed for subsequent agent boluses or infusion via a volumetric pump. he American College of Obstetricians and Gynecologists (2017 a) concludes that under appropriate physician supervision, labor and delivery nursing personnel who have been specifically trained in the management of epidural infusions should be able to adjust dosage and also discontinue infusions.


Obstentrics_Williams

Obstentrics_Williams. Complete analgesia for the pain of labor and vaginal delivery necessitates a block from the TIO to the S5 dermatomes (see Fig. 25-1). For cesarean delivery, a block extending from the T4 to the S1 derma tomes is desired. The efective spread of anesthetic depends on the catheter tip location; the dose, concentration, and volume of anesthetic agent used; and whether the mother is head-down, horizontal, or head-up (Setayesh, 2001). Individual variations in anatomy or presence of synechiae may preclude a completely satisfactory block. Finally, the catheter tip may migrate from its original location during labor.


Obstentrics_Williams

Obstentrics_Williams. One example of the sequential steps and techniques for performance of epidural analgesia is detailed in Table 25-7. Before injection of the local anesthetic therapeutic dose, a test dose is given. The woman is observed for features of toxicity from intravascular injection and for signs of high or total blockade from subdural or subarachnoid injection. If these are absent, only then is a full dose given. Analgesia is maintained by intermittent boluses of similar volume or by small volumes delivered continuously by infusion pump (Halpern, 2009). Current pumps used for epidural analgesia ofer a programmed intermittent epidural bolus (PIEB) mode, which reduces the required concentration of local anesthetics, the degree of lower extremity motor blockade, and rates of operative vaginal delivery (Capogna, 2011). he addition of small doses of a short-acting narcotic-fentanyl or sufentanil-has been shown to improve analgesic eicacy while avoiding motor blockade (Chestnut,


Obstentrics_Williams

Obstentrics_Williams. TABLE 25-7. Technique for Labor Epidural Analgesia Informed consent is obtained, and the obstetrician consulted Monitoring includes the following: Blood pressure every 1 to 2 minutes for 15 minutes ater giving a bolus of local anesthetic Continuous matenal heart rate monitoring during analgesia induction Hydration with 500 to 1000 mL of lactated solution The woman assumes a lateral decubitus or sitting position The epidural space is identified with a loss-of-resistance technique The epidural catheter is threaded 3 to 5 cm into the epidural space A test dose of 3 mL of 1.5% lidocaine with 1 :200,000 epinephrine or 3 mL of 0.25% bupivacaine with 1 :200,000 epinephrine is injected after careful aspiration to avert injection and after a uterine contraction. This minimizes the chance of confusing tachycardia that results from labor pain with tachycardia from intravenous injection of the test dose.


Obstentrics_Williams

Obstentrics_Williams. If the test dose is negative, 10-15 mL of 0.0625-0.125% bupivacaine are injected to achieve a sensory TlO level. Ater 15 to 20 minutes, the block is assessed using loss of sensation to cold or pinprick. If no block is evident, the catheter is replaced. If the block is asymmetrical, the epidural catheter is withdrawn 0.5 to 1s.0 cm and an additional 5 to 10 mL of 0.0625-0.125% bupivacaine is injected. If the block remains inadequate, the catheter is replaced. The woman is positioned in the lateral or semilateral position to avoid aortocaval compression. Subsequently, maternal blood pressure is recorded every 5 to 15 minutes. The fetal heart rate is monitored continuously. The level of analgesia and intensity of motor blockade are assessed at least hourly. Reproduced with permission from Glosten B: Local anesthetic techniques. In Chestnut DH (ed): Obstetric Anesthesia: 2nd ed. St Louis, Mosby, 1999.


Obstentrics_Williams

Obstentrics_Williams. Reproduced with permission from Glosten B: Local anesthetic techniques. In Chestnut DH (ed): Obstetric Anesthesia: 2nd ed. St Louis, Mosby, 1999. 1988). As with spinal blockade, close monitoring, including the level of analgesia, is imperative and must be performed by trained personnel. Appropriate resuscitation equipment and drugs must be available during administration of epidural analgesia. Higher or Total Spinal Blockade. In general, complications with epidural analgesia are similar to those with spinal analgesia (see Table 25-5). Dural puncture with inadvertent subarachnoid injection may cause total spinal blockade. Sprigge and Harper (2008) cited an incidence of 0.91 percent recognized accidental dural punctures at the time of epidural analgesia in more than 18,000 women. Personnel and facilities must be immediately available to manage this complication as described earlier (p. 491). In other aspects, however, complications are unique and inherent to epidural analgesia use.


Obstentrics_Williams

Obstentrics_Williams. Inefective Analgesia. Using currently popular continuous epidural infusion regimens such as 0.125-percent bupivacaine with 2-�g/mL fentanyl, 90 percent of women rate their pain relief as good to excellent (Sharma, 1997). lternatively, a few women ind epidural analgesia to be inadequate for labor. In a study of almost 2000 parturients, Hess and associates (2001) found that approximately 12 percent complained of three or more episodes of pain or pressure. Risk factors for such breakthrough pain included nullipariry and heavier fetal weights. Dresner and colleagues (2006) also reported that epidural analgesia was more likely to fail as body mass index increased. If epidural analgesia is allowed to dissipate before another Injection of anesthetic drug, subsequent pain relief may be delayed, incomplete, or both.


Obstentrics_Williams

Obstentrics_Williams. In some women, epidural analgesia is insuicient for cesarean delivery. For example, in a Maternal Fetal Medicine Units (MFMU) Network study, 4 percent of women initially given epidural analgesia required a general anesthetic for cesarean delivery (Bloom, 2005). Also at times, perineal analgesia for delivery is diicult to obtain, especially with the lumbar epidural technique. When this situation is encountered, pudendal block or systemic analgesia or rarely general anesthesia may be added.


Obstentrics_Williams

Obstentrics_Williams. Hypotension. Sympathetic blockade from epidurally injected analgesic agents can cause hypotension and decreased cardiac output. Despite precautions, hypotension is the most frequent side efect and is severe enough to require treatment in a third of women (Sharma, 1997). According to Miller and coworkers (2013), hypotension is more common-20 percent-in women with an admission pulse pressure <45 mm Hg, compared with 6 percent in those whose pulse pressure is >45 mm Hg. In normal gravidas, hypotension induced by epidural analgesia usually can be prevented by rapid infusion of 500 to 1000 mL of crystalloid solution as described for spinal analgesia. Maintaining a lateral position also minimizes hypotension.


Obstentrics_Williams

Obstentrics_Williams. Maternal Fever. Fusi and colleagues (1989) observed that the mean temperature rose in laboring women given epidural analgesia. Subsequently, several randomized and retrospective cohort studies have confirmed that some women develop intrapartum fever following this procedure. Many studies are limited by inabiliry to control for other risk factors such as labor length, duration of ruptured membranes, and number of vaginal examinations. With this in mind, the frequency of intrapartum fever associated with epidural analgesia was found by Lieberman and O'Donoghue (2002) to be 10 to 15 percent above the baseline rate.


Obstentrics_Williams

Obstentrics_Williams. The two general theories concerning the etiology of maternal hyperthermia are maternaletal inection or dysregulation of body temperature. Dashe and coworkers (1999) studied placental histopathology in laboring women given epidural analgesia and identified intrapartum fever only when there was placental inflammation. This suggests that fever is due to infection. he other proposed mechanisms include alteration of the hypothalamic thermoregulatory set point; impairment of peripheral thermoreceptor input to the central nervous system, with selective blockage of warm stimuli; or imbalance between heat production and heat loss. Sharma (2014) randomized 400 nulliparas with labor epidural analgesia to receive cefoxitin 2 g prophylactically versus placebo. It was hypothesized that epidural-related fever was due to infection and that prophylactic antimicrobial use should significantly reduce the rate of fever. Approximately equal proportions-about 40 percentof women developed fever > 38°C


Obstentrics_Williams

Obstentrics_Williams. fever was due to infection and that prophylactic antimicrobial use should significantly reduce the rate of fever. Approximately equal proportions-about 40 percentof women developed fever > 38°C during labor. This suggests that infection is unlikely to be the cause of fever.


Obstentrics_Williams

Obstentrics_Williams. Back Pain. An association between epidural analgesia and subsequent back pain has been reported by some but not all. In a prospective cohort study, Butler and Fuller (1998) reported that back pain after delivery was common with epidural analgesia, however, persistent pain was uncommon. Based on their systematic review, Lieberman and O'Donoghue (2002) concluded that available data do not support an association between epidural analgesia and development of de novo, long-term backache. Miscellaneous Complications. A spinal or epidural hematoma is a rare complication of an epidural catheter (Grant, 2007). Epidural abscesses are equally infrequent (Darouiche, 2006). And uncommonly, the plastic epidural catheter can be sheared of (Noblett, 2007).


Obstentrics_Williams

Obstentrics_Williams. Most studies, including the ive from Parkland Hospital, report that epidural analgesia prolongs labor and increases the use of oxytocin stimulation (Table 25-8). Alexander and associates (2002) examined the efects of epidural analgesia on the Friedman (1955) labor curve described in Chapter 22 (p. 432). Compared with original Friedman criteria, epidural analgesia prolonged the active phase of labor by 1 hour. As further shown in Table 25-8, epidural analgesia also increased the need for operative vaginal delivery because of prolonged second-stage labor. But importantly, this led to no greater rates of adverse neonatal efects.


Obstentrics_Williams

Obstentrics_Williams. This association among epidural analgesia and prolonged second-stage labor and operative vaginal delivery has been attributed to anesthesia-induced motor blockade and resultant impaired matenal expulsive eforts. Craig and colleagues (2015) randomized 310 nulliparous women with labor epidural analgesia to bupivacaine plus fentanyl or fentanyl alone during second-stage labor. Epidural bupivacaine analgesia did cause motor blockade during the second stage, however, the duration of the second stage was not increased. TABLE 25-8. Selected Labor Events in 2703 Nulliparous Women Randomized to Epidural Analgesia First-stage duration 8.1 ± 5 7.5 ± 5 0.01s1 (hr)b Second-stage 60 ± 56 47 ± 57 <0.001 duration (min) Oxytocin ater 641 (48) 546 (40) <0.001 Type of delivery SVD 1027 (77) 11s22 (82) <0.001 Forceps 172 (l3) 101 (7) <0.001 Cesarean 140 (10.5) 141 (10.3) 0.92 aData are presented as n (%) or mean ± SD. bFirst stage = initiation of analgesia to complete cervical dilatation.


Obstentrics_Williams

Obstentrics_Williams. bFirst stage = initiation of analgesia to complete cervical dilatation. SVD = spontaneous vaginal delivery. Adapted with permission from Sharma SK, Mcintire DD, Wiley J, et al: Labor analgesia and cesarean delivery. An individual patient meta-analysis of nulliparous women, Anesthesiology. 2004 Jan;l 00(1 ):142-148. Fetal Heart Rate. Hill and associates (2003) examined the efects of epidural analgesia with 0.25-percent bupivacaine on fetal heart rate patterns. Compared with intravenous meperidine, no deleterious efects were identified. Reduced beat-co-beat variability and fewer accelerations were more frequent sequelae in fetuses whose mothers received meperidine (Chap. 24, p. 462). Based on their systematic review, Reynolds and coworkers (2002) reported that epidural analgesia was associated with improved neonatal acid-base status compared with meperidine.


Obstentrics_Williams

Obstentrics_Williams. Cesarean Delivery Rates. A contentious issue in the past was whether epidural analgesia increased the risk for cesarean delivery. Supporting evidence for this view came from the era when dense blocks of local anesthetic agents were used that impaired motor function and therefore likely did contribute to higher cesarean delivery rates. As techniques were refined, however, many investigators came to believe that epidural administration of dilute anesthetic solutions did not increase cesarean delivery rates. Several studies conducted at Parkland Hospital were designed to answer this and related questions. From 1995 to 2002, a total of 2703 nulliparas at term and in spontaneous labor were enrolled in ive trials to evaluate epidural analgesia techniques compared with methods of intravenous meperidine administration. he results from these are summarized in Figure 25-4 and show that epidural analgesia does not signiicantly raise cesarean delivery rates. Timing of Epidural Placement


Obstentrics_Williams

Obstentrics_Williams. Timing of Epidural Placement In several retrospective studies, epidural placement in early labor was linked to an increased risk of cesarean delivery Ramin et ai, 1995 Sharma et ai, 1997 Gambling et ai, 1998 Lucas et ai, 2001 Sharma et ai, 2002 I OR (95% el) Force on Obstetrical Anesthesia (2016).I Epidural hematomas are rare, and inci 1.01 (0.79,e1.30) dence of nerve damage from a hematoma is estimated to be 1 in 150,000 (Grant, 2007). he American College of Obstetri 1.20 (0.73, 1.97) cians and Gynecologists (2016b) has conI cluded that selected women with platelet 0.77 (0.31e, 1.91e) counts of 80,000 to 100,000/LL may be


Obstentrics_Williams

Obstentrics_Williams. I candidates for regional analgesia. Caveats --: -1.13 (0.65, 1.97) include a stable platelet count, no acquired or congenital coagulopathy, normal plateI let function, no antiplatelet-specific drugs, 1.05 (0.68, 1.63) and anticoagulation parameters, describedI next, that are met. Counts between 50,000 0.81 (0.41e, 1.61e) and 80,000 require an individualizedI decision on risks and benefits (van Veen, 1.04 (0.81e,e1.34) 2010). Single-shot spinal anesthesia with a 25-gauge needle is less traumatic than epiI dural or combined spinal-epidural anesthe sia with a 17-or 18-gauge epidural needle 0.0 0.4 0.8 1.2 1.6 2.0 platelets in this range. FIGURE 25-4 Results offive studies comparing the incidence of cesarean delivery in women given either epidural analgesia or intravenous meperidine. The individual


Obstentrics_Williams

Obstentrics_Williams. FIGURE 25-4 Results offive studies comparing the incidence of cesarean delivery in women given either epidural analgesia or intravenous meperidine. The individual Anticoagulation. Women recelvmg odds ratios (ORs) with 95-percent confidence intervals (Cis) for each randomized study, coagulation therapy who are given regional as well as overall crude and adjusted ORs with 95-percent Cis, are shown. An OR <1o.0 analgesia are at increased risk for spinal cord favored epidural over meperidine analgesia. (Reproduced with permission from Sharma


Obstentrics_Williams

Obstentrics_Williams. SK, Mcintire DO, Wiley J, et al: Labor analgesia and cesarean delivery. An individual patient meta-analysis of nulliparous women, Anesthesiology. 2004 Jan;l00(1):142-148.) sion (Chap. 52, p. 1014). Our practice pat (Lieberman, 1996; Rogers, 1999; Seyb, 1999). These observations prompted at least ive randomized trials, which showed that timing of epidural placement has no efect on the risk of cesarean birth, forceps delivery, or fetal malposition (Chestnut, 1994a,b; Ohel, 2006; Wong, 2005, 2009). Thus, withholding epidural placement until some arbitrary cervical dilation has been attained is unsupportable and serves only to deny women maximal labor pain relief.


Obstentrics_Williams

Obstentrics_Williams. he relative safety of epidural analgesia is relected by the extraordinary earlier experiences reported by Crawford (1985) from the Birmingham Maternity Hospital in England. Similarly, there were no anesthesia-related maternal deaths among nearly 20,000 women who received epidural analgesia in the MFMU Network study cited earlier (Bloom, 2005). And, Ruppen and associates (2006) reviewed data from 27 studies involving 1.4 million pregnant women who received epidural analgesia. hey calculated risks of 1: 145,000 for deep epidural infection, 1: 168,000 for epidural hematoma, and 1 :240,000 for persistent neurological injury. Thrombocytopenia. For epidural analgesia, contraindications are similar to those with spinal analgesia (see Table 25-6). Although low platelet counts are intuitively worrisome, the level at which epidural bleeding might develop is unknown according to the American Society of Anesthesiologists Task tern includes the following: 1.


Obstentrics_Williams

Obstentrics_Williams. Women receiving unfractionated heparin therapy should be able to receive regional analgesia if they have a normal activated partial thromboplastin time (aPTT). 2. Women receiving prophylactic doses of unfractionated heparin or low-dose aspirin are not at increased risk and can be ofered regional analgesia. 3. For women receiving once-daily, low-dose low-molecularweight heparin, regional analgesia should not be placed until 12 hours after the last injection. 4. Low-molecular-weight heparin should be withheld for at least 2 hours after epidural catheter removal. 5. he safety of regional analgesia in women receiving twicedaily low-molecular-weight heparin has not been studied suiciently. It is not known whether delaying regional analgesia for 24 hours after the last injection is adequate.


Obstentrics_Williams

Obstentrics_Williams. Severe Preeclampsia-Eclampsia. Potential concerns with epidural analgesia in women with severe preeclampsia include hypotension as well as hypertension from pressor agents given to correct hypotension. Additionally, pulmonary edema following infusion of large volumes of crystalloid is a potential risk. These are outweighed by disadvantages of general anesthesia. Tracheal intubation may be diicult because of upper airway edema. Moreover, general anesthesia can lead to severe, sudden hypertension that can cause pulmonary or cerebral edema or intracranial hemorrhage. With improved techniques for infusion of dilute local anesthetics into the epidural space, most obstetricians and obstetrical anesthesiologists have come to favor epidural block ade for labor and delivery in women with severe preeclamp sia. here seems to be no argument that epidural analgesia for women with severe preeclampsia-eclampsia can be safely used cians (Lucas, 2001).


Obstentrics_Williams

Obstentrics_Williams. Women with severe preeclampsia have remarkably diminished intravascular volumes compared with unafected gravidas (Zeeman, 2009). Conversely, extravascular volume is increased because of the capillary leak caused by endothelial cell activation (Chap. 40, p. 717). his imbalance is manifested as pathological peripheral edema, proteinuria, ascites, and total lung water. For all of these reasons, aggressive volume replacement increases the risk for pulmonary edema, especially in the irst 72 hours postpartum. In one study, Hogg and associates (1999) reported that 3.5 percent of women with severe preeclampsia developed pulmonary edema when preloaded without a protocol limitation to volume. Importantly, this risk can be reduced or obviated with judicious prehydration-usually with 500 to 1000 mL of crystalloid solution. Speciically, in the study by Lucas and colleagues (2001), there were no instances of pulmonary edema among the women in whom the crystalloid preload was limited to 500 mL.


Obstentrics_Williams

Obstentrics_Williams. mL of crystalloid solution. Speciically, in the study by Lucas and colleagues (2001), there were no instances of pulmonary edema among the women in whom the crystalloid preload was limited to 500 mL. Moreover, vasodilation produced by epidural blockade is less abrupt if the analgesia level is achieved slowly with dilute solutions of local anesthetic agents. This allows maintenance of blood pressure while simultaneously avoiding infusion of large crystalloid volumes.


Obstentrics_Williams

Obstentrics_Williams. he combination of spinal and epidural techniques has increased in popularity and may provide rapid and efective analgesia for labor and for cesarean delivery. An introducer needle is irst placed in the epidural space. A small-gauge spinal needle is then introduced through the epidural needle into the subarachnoid space-this is called the needle-throughneedle technique (see Fig. 25-3). A single bolus of an opioid, sometimes in combination with a local anesthetic, is injected into the subarachnoid space. The spinal needle is withdrawn, and an epidural catheter is then placed through the introducer needle. A subarachnoid opioid bolus results in the rapid onset of profound pain relief with virtually no motor blockade. he epidural catheter permits repeated analgesia dosing. Miro and associates (2008) compared epidural analgesia with combined spinal-epidural analgesia for labor in 6497 women and found the overall outcomes and complications to be similar for the two techniques. In a


Obstentrics_Williams

Obstentrics_Williams. (2008) compared epidural analgesia with combined spinal-epidural analgesia for labor in 6497 women and found the overall outcomes and complications to be similar for the two techniques. In a randomized comparison, however, Abrao and colleagues (2009) reported that combined spinal-epidural analgesia was associated with a greater incidence of fetal heart rate abnormalities related to uterine hypertonus. Beamon and coworkers (2014) reported similar results .


Obstentrics_Williams

Obstentrics_Williams. here is emerging interest in continuous spinal analgesia for relief of labor pain. Arkoosh (2008) randomized 429 laboring women to either continuous spinal or conventional epidural analgesia. Complication rates between these two neuraxial techniq ues did not difer. Tao and colleagues (2015) reported their experiences with 113 women. With a dilute bupivacaine solution for analgesia, they found no cases of peripheral nerve injury and a headache rate of2.6 percent. he utility of continuous spinal analgesia in labor and delivery remains to be further studied. A local block is occasionally useful to augment an inadequate or "patchy" regional block that was given emergently. Rarely, local iniltration may be needed to perform an emergent cesarean delivery to save the life of a fetus in the absence of anesthesia support (Young, 2012).


Obstentrics_Williams

Obstentrics_Williams. In one technique, the skin is iniltrated along the proposed incision, and the subcutaneous, muscle, and rectus sheath layers are injected as the abdomen is opened. Up to a total of 70 mL of 0.5-percent lidocaine with 1 :200,000 epinephrine is prepared for iniltration. Injection of large volumes into the fatty layers, which are relatively devoid of nerve supply, is avoided to limit the total dose of local anesthetic needed. A second technique involves a ield block of the major branches supplying the abdominal wall, to include the 10th, 11 th, and 12th intercostal nerves and the ilioinguinal and genitofemoral nerves (Nandagopal, 2001). As shown in 25-5, the former group of nerves is located at a point midway


Obstentrics_Williams

Obstentrics_Williams. FIGURE 25-5 Local anesthetic block for cesarean delivery. The first injection site is halfway between the costal margin and iliac crest in the midaxillary line to block the 10th, 11 th, and 12th intercostal nerves. A second injection at the external inguinal ring blocks branches of the genitofemoral and ilioinguinal nerves. These two sites are infiltrated bilaterally. The fifth and final site is along the line of proposed skin incision.


Obstentrics_Williams

Obstentrics_Williams. between the costal margin and iliac crest in the midaxillary line. he latter group is found at the level of the external inguinal ring. Only one skin puncture is made at each of the four sites (right and left sides). At the intercostal block site, the needle is directed medially, and injection is carried down to the fascia, avoiding injection of the subcutaneous fat. Approximately 5 to 8 mL of 0.5-percent lidocaine is injected. The procedure is repeated at a 45-degree angle cephalad and caudad to this line. he other side is then injected. At the ilioinguinal and genitofemoral sites, the injection is started at a site 2 to 3 cm lateral from the pubic tubercle at a 45-degree angle. Finally, the skin overlying the planned incision is injected.


Obstentrics_Williams

Obstentrics_Williams. Trained personnel and specialized equipment including alternative airways, video laryngoscopes, and fiberoptic intubation scopes are mandatory for the safe use of general anesthesia. A common cause of death cited for general anesthesia is failed intubation. This occurs in approximately 1 of every 400 general anesthetics administered to pregnant women (Kinsella, 2015). There is a growing trend to continue surgery with a supraglottic airway device, such as a laryngeal mask airway, in the event of a failed intubation (Mushambi, 2015). Because of these relatively greater morbidity and mortality rates, neuraxial analgesia is the preferred method of pain control and should be used unless contraindicated (see Table 25-6). Indeed, in two reports from the MFMU Network, 93 percent of more than 54,000 cesarean deliveries were performed using neuraxial analgesia (Bloom, 2005; Brookfield, 2013). A higher incidence of general anesthesia use for nonwhite women has been reported (Butwick,i2014).


Obstentrics_Williams

Obstentrics_Williams. Before anesthesia induction, several steps are taken to help minimize complication risks: 1. Antacid administration shortly before anesthesia induction has probably lowered mortality rates from general anesthesia more than any other single practice. The American Society of Anesthesiologists Task Force on Obstetrical Anesthesia (2016) recommends timely administration of a nonparticulate antacid, an Hrreceptor antagonist, or metoclopramide. For many years, we have administered 30 mL of Bicitra-sodium citrate with citric acid-a few minutes before anesthesia induction by either general or major neuraxial block. If more than 1 hour has passed ater the first dose was given and anesthesia has not yet been induced, then a second dose is given. 2.


Obstentrics_Williams

Obstentrics_Williams. 2. Lateral uterine displacement is also provided, as the uterus may compress the inferior vena cava and aorta when the mother is supine. With uterine displacement, the duration of general anesthesia has less efect on neonatal condition than if the woman remains supine. 3. Preoxygenation is done because functional reserve lung capacity is reduced and the pregnant woman becomes hypoxemic more rapidly during periods of apnea. Obesity exacerbates this tendency (McClelland, 2009). To minimize hypoxia between the time of muscle relaxant injection and intubation, oxygen is introduced into the lungs in place of nitrogen. 1bis preoxygenation is accomplished by administering 100-percent oxygen via face mask for 2 to 3 minutes before anesthesia induction. In an emergency, four vital capacity breaths of 100-percent oxygen via a tight breathing circuit will provide similar beneit (Norris, 1985).


Obstentrics_Williams

Obstentrics_Williams. Almost all parturients are considered to have a full stomach, which necessitates a rapid-sequence induction. Namely, an intravenous anesthetic and rapid-onset muscle relaxant are simultaneously administered while cricoid pressure is applied by an assistant.


Obstentrics_Williams

Obstentrics_Williams. Of anesthetics, intravenous propofol or etomidate is widely used and ofers a smooth, rapid induction. Propofol is associated with a quick onset and recovery, and it may lower the incidence of nausea and vomiting. Since thiopental is no longer available, propofol is used as the primary agent for induction of general anesthesia with a reasonable safety record. Etomidate is the induction agent of choice for hemodynamically unstable parturients. Alternatively, ketamine can be used but is avoided in hypertensive women. For muscle relaxation, succinylcholine is an ultrafast-onset, short-acting agent commonly used in obstetrics. It ofers intense muscle relaxation to aid endotracheal intubation but also allows for the rapid return of spontaneous respiration in the case of failed intubation. Rocuronium is an alternative muscle relaxant if succinylcholine is contraindicated or unavailable. Its duration is much longer than succinylcholine unless its efect is reversed by sugammadex (Bridion), a


Obstentrics_Williams

Obstentrics_Williams. is an alternative muscle relaxant if succinylcholine is contraindicated or unavailable. Its duration is much longer than succinylcholine unless its efect is reversed by sugammadex (Bridion), a specific binding agent recently approved by the FDA. To decrease the incidence of fetal respiratory depression, an intermediate or long-acting opioid is usually avoided upon induction of general anesthesia. The intense stimulation from direct laryngoscopy may worsen hypertension and tachycardia in certain women. Remifentanil, an ultrashort-acting narcotic, has been used during induction for cesarean deliveries with favorable maternal hemodynamics and fetal outcome (Heesen, 2013).


Obstentrics_Williams

Obstentrics_Williams. During induction and intubation, cricoid pressure is applied by a trained assistant to occlude the esophagus and thereby minimize regurgitation of the gastric contents-the Sellick maneuver. Positive mask ventilation during rapid sequence induction is typically avoided to lower the risk of increased intragastric pressure, which raises the risk of vomiting. Surgery should begin only after an airway is secured or, depending on the status of the mother and fetus, efective ventilation has been established.


Obstentrics_Williams

Obstentrics_Williams. Although uncommon, failed intubation is a major cause of anesthesia-related maternal mortality. A history of prior difficult intubation and a careful anatomical assessment of the neck and maxillofacial, pharyngeal, and laryngeal structures may help predict intubation complications. Even in cases in which the initial airway assessment was unremarkable, edema may develop intrapartum and present considerable challenges. Morbid obesity is another major factor for failed or diicult intubation. The American Society of Anesthesiologists Task Force on Obstetrical Anesthesia (2016) stresses the importance of appropriate preoperative preparation. This includes the immediate availability of specialized equipment such as diferent-shaped laryngoscopes, laryngeal mask airways, a fiberoptic bronchoscope, and a transtracheal ventilation set, as well as liberal use of awake oral intubation techniques.


Obstentrics_Williams

Obstentrics_Williams. Ideally, an operative procedure is initiated only after it has and that adequate ventilation can be accomplished. Even with an abnormal fetal heart rate pattern, cesarean delivery initiation will only serve to complicate matters if there is diicult or failed intubation. Frequently, the woman must be allowed to awaken and a diferent technique used, such as an awake intubation or regional analgesia.


Obstentrics_Williams

Obstentrics_Williams. Following failed intubation, the woman is ventilated by mask and cricoid pressure is applied to reduce the aspiration risk. Surgery may proceed with mask ventilation, or the woman may be allowed to awaken. In those cases in which the woman has been paralyzed and ventilation cannot be reestablished by insertion of an oral airway, by laryngeal mask airway, or by use of a iberoptic laryngoscope to intubate the trachea, then a life-threatening emergency exists. To restore ventilation, percuraneous or even open cricothyrotomy is performed and jet ventilation begun. Failed intubation drills have been recommended to optimize the response to such an emergency.


Obstentrics_Williams

Obstentrics_Williams. With the endotracheal tube secured, anesthesia is maintained with a halogenated agent, typically mixed with air or nitrous oxide. he most commonly used inhalational anesthetics in the United States include deslurane and sevolurane. Both have low solubility in blood and fat. As a result, they ofer faster onset and clearance than more traditional gases such as isolurane. In addition to providing amnesia, they produce profound uterine relaxation when given in high concentrations. his is advantageous when relaxation is a requisite, such as for internal podalic version of the second twin, for breech decomposition, or for replacement of the acutely inverted uterus. That said, unless the woman is alread) under general anesthesia, intravenous nitroglycerine is preferred by many in such situations.


Obstentrics_Williams

Obstentrics_Williams. he endotracheal tube may be safely removed only if the woman is conscious to a degree that enables her to follow commands and is capable of maintaining oxygen saturation with spontaneous respiration. Consideration is given to emptying the stomach via a nasogastric tube before extubation. As induction has become safer, extubation may now be relatively more perilous. Of 15 anesthesia-related deaths of pregnant women from 1985 to 2003 in Michigan, none occurred during induction. Five resulted from hypoventilation or airway obstruction during emergence, extubation, or recovery (Mhyre, 2007). Massive gastric acidic inhalation may cause pulmonary insufficiency from aspiration pneumonitis. In the past, this was the most common cause of anesthetic deaths in obstetrics and therefore deserves special attention. To minimize this risk, antacids are given rourinely, intubation is accompanied by cricoid pressure, and regional analgesia is employed when possible.


Obstentrics_Williams

Obstentrics_Williams. According to the American Society of Anesthesiologists Task Force on Obstetrical Anesthesia (2016) and the merican College of Obstetricians and Gynecologists (2017b), data are insuicient regarding fasting times for clear liquids and the risk of pulmonary aspiration during labor. Recommendations are that modest amounts of clear liquids such as water, clear tea, black cofee, carbonated beverages, and pulp-free fruit juices be allowed in uncomplicated laboring women (Chap 22, p. 437). Obvious solid foods are avoided. A fasting period of 6 to 8 hours for solid food is recommended for uncomplicated parturients prior to undergoing elective cesarean delivery or puerperal tubal ligation.


Obstentrics_Williams

Obstentrics_Williams. O'Sullivan (2009) randomized 2426 low-risk nulliparas to consume either water and ice chips alone or small amounts of bread, biscuits, vegetables, fruits, yogurt, soup, and fruit juice. Approximately 30 percent of women in each arm of the study underwent cesarean delivery. No cases of aspiration occurred during the study, although approximately a third of women in each study arm vomited during labor or delivery. Epidural analgesia during labor was used in this study, although the authors did not report the type of anesthesia used for cesarean deliveries. Presumably, neuraxial analgesia was used, and this greatly minimized the pulmonary aspiration risk. Given the low prevalence of aspiration, this trial was not powered to measure whether feeding during labor was safe (Sperling, 2016).


Obstentrics_Williams

Obstentrics_Williams. In 1952, Teabeaut demonstrated experimentally that if the pH of aspirated fluid was <2.5, severe chemical pneumonitis developed. It was later demonstrated that the pH of gastric juice in nearly half of women tested intrapartum was <2.5 (Taylor, 1966). The right mainstem bronchus usually ofers the simplest pathway for aspirated material to reach the lung parenchyma, and therefore, the right lower lobe is most often involved. In severe cases, there is bilateral widespread involvement. The woman who aspirates may develop evidence of respiratory distress immediately or several hours after aspiration, depending in part on the material aspirated and the severity of the response. Aspiration of a large amount of solid material causes obvious airway obstruction. Smaller particles without acidic liquid may lead to patchy atelectasis and later to bronchopneumonia.


Obstentrics_Williams

Obstentrics_Williams. When highly acidic liquid is inspired, decreased oxygen saturation along with tachypnea, bronchospasm, rhonchi, rales, atelectasis, cyanosis, tachycardia, and hypotension are likely to develop. At the injury sites, there is pulmonary capillary leakage and exudation of protein-rich fluid containing numerous erythrocytes into the lung interstitium and alveoli. his causes decreased pulmonary compliance, shunting of blood, and severe hypoxemia. Radiographic changes may not appear immediately, and these may be variable, although the right lung most often is afected. hus, chest radiographs alone should not be used to exclude aspiration.


Obstentrics_Williams

Obstentrics_Williams. he methods recommended for treatment of aspiration have changed appreciably in recent years, indicating that previous therapy was not very successful. Suspicion of aspiration of gastric contents demands close monitoring for evidence of pulmonary damage. Respiratory rate and oxygen saturation as measured by pulse oximetry are the most sensitive and earliest indicators of injury.


Obstentrics_Williams

Obstentrics_Williams. Inhaled luid should be immediately and thoroughly wiped from the mouth and removed from the pharynx and trachea by suction. Saline lavage may further disseminate the acid throughout the lung and is not recommended. If large particulate matter is inspired, bronchoscopy may be indicated to relieve airway obstruction. No convincing evidence supports that corticosteroid therapy or prophylactic antimicrobial administration is beneicial (Marik, 2001). If infection develops, however, then vigorous treatment is given. If acute respiratory failure develops, mechanical ventilation with positive end-expiratory pressure may be lifesaving (Chap. 47, p. 919).


Obstentrics_Williams

Obstentrics_Williams. patient satisfaction, minimizing side efects, aiding unctional capacity, and preventing prolonged hospital stays (Lavoie, 2013). In a prospective study, 96 percent of women reported pain immediately ater delivery (Eisenach, 2008). he incidence of persistent pain 1 and 2 years following cesarean delivery was reported to approximate 20 percent (Hannah, 2004; Kainu, 2010).


Obstentrics_Williams

Obstentrics_Williams. he American Society of Anesthesiologists (2016) recommends neuraxial opioids for postoperative analgesia. Although most cesarean deliveries in the United States are performed under neuraxial anesthesia, in certain situations a peripheral nerve block such as a transversus abdominis plane (TAP) block may be considered (McDonnell, 2007). hese include cases in which the parturient did not receive neuraxial opioids, underwent general anesthesia, or has persistent pain following neuraxial anesthesia. It is usually performed under ultrasound guidance and involves injection of a local anesthetic into the transversus abdominis plane between the internal oblique and transversus abdominis muscles. he nerves lying in this plane supply the anterior abdominal wall at the T 6 to L1 dermatomes. A metaanalysis of 31 controlled trials showed that ultrasoundguided TAP block marginally reduced opioid consumption at 6 hours following abdominal surgery (Baeriswyl, 2015).


Obstentrics_Williams

Obstentrics_Williams. Abrao KC, Francisco RP, Miyadahira S, et al: Elevation of uterine basal tone and fetal heart rate abnormalities after labor analgesia: a randomized controlled trial. Obstet Gynecol 113(10):41,2009 Alexander JM, Sharma SK, McIntire DD, et al: Epidural analgesia lengthens the Friedman active phase ofolabor. Obstet Gynecol 100:46,o2002 American College of Obstetricians and Gynecologists: Practice advisory: FDA warnings regarding use of general anesthetics and sedation drugs in young children and pregnant women. 2016a. Available at: http://www.acog.org/ About-ACOG/News-Room/Practice-Advisories/FDA-Warnings-Rega rding-Use-of-General-Anesthetics-and-Sedation-Drugs. Accessed January 30, 20o17 American College of Obstetricians and Gynecologists: hrombocytopenia in pregnancy. Practice Bulletin 166, September 20o16b American College of Obstetricians and Gynecologists: Obstetric analgesia and anesthesia. Practice Bulletin 177, Aprilo20o17a


Obstentrics_Williams

Obstentrics_Williams. American College of Obstetricians and Gynecologists: Oral intake during labor. Committee Opinion No. 44o1, September 2009, Reairmed 20o17b American Society of Anesthesiologists: Task Force on Obstetrical Anesthesia: practice guidelines for obstetrical anesthesia. Anesthesiology 124:270, 20o16 Angle P, Tang SL, Thompson D, et al: Expectant management of postdural puncture headache increases hospital length of stay and emergency room visits. Can J Anaesth 52(4):397, 2005


Obstentrics_Williams

Obstentrics_Williams. Arkoosh V, Palmer C, Yun E, et al: A randomized, double-masked, multicenter comparison of the safety of continuous intrathecal labor analgesia using a 28-gauge catheter versus continuous epidural labor analgesia. Anesthesiology 108(2):286, 2008 Baeriswyl M, Kirkham KR, Kern C, et al: he analgesic eicacy of ultrasoundguided transversus abdominis plane block in adult patients: a meta-analysis. AnesthAnalg 121(6):1640,2015 Barbieri L, Camann W, McGovern C: Nitrous oxide for labor pain. OBG Manag 26(12):10,o2014 Beamon C, Stuebe A, Edwards L, et al: Efect of mode of regional anesthesia on neonatal outcomes in preeclamptic patients. Am J Obstet Gynecol 210:S173,o2014 Bell ED, Penning DH, Cousineau EF, et al: How much labor is in a labor epidural? Manpower cost and reimbursement for an obstetric analgesia service in a teaching institution. Anesthesiology 92:851, 2000 Bloom SL, Spong CY, Weiner SJ, et al: Complications of anesthesia for cesarean delivery. Obstet Gynecol 106:28o1, 2005


Obstentrics_Williams

Obstentrics_Williams. analgesia service in a teaching institution. Anesthesiology 92:851, 2000 Bloom SL, Spong CY, Weiner SJ, et al: Complications of anesthesia for cesarean delivery. Obstet Gynecol 106:28o1, 2005 Bricker L, Lavender T: Parenteral opioids for labor pain relief: a systematic review. Am J Obstet Gynecol 186:S94, 2002 Brookield K, Osmundson S, Jaqvi M, et al: General anesthesia at cesarean delivery portends worse maternal and neonatal outcomes. Abstract No. 672. Am J Obstet Gynecol 208(1 Suppl):S28, 2013 Butler R, Fuller J: Back pain following epidural anaesthesia in labour. Can J Anaesth 45:724, 1998 Burwick A, Blumenfeld Y, Brookfeld K, et al: Ethnic disparities among patients undergoing general anesthesia for cesarean delivery. Am J Obstet Gynecol 21o0:S259,o20o14


Obstentrics_Williams

Obstentrics_Williams. Capogna G, Camorcia M, Stirparo S, et al: Programmed intermittent epidural bolus versus continuous epidural infusion for labor analgesia: the efects on maternal motor function and labor outcome. A randomized double-blind study in nulliparous women. Anesth Analg 113(4):826, 2011 Centers for Disease Control and Prevention: Bacterial meningitis after intrapartum anesthesia-New York and Ohio, 2008-2009. MMWR 59(3):65, 2010 Chestnut DH, McGrath JM, Vincent RD Jr, et al: Does early administration of epidural analgesia afect obstetric outcome in nulliparous women who are in spontaneous labor? Anesthesiology 80: 1201, 1994a Chestnut DH, Owen CL, Bates IN, et al: Continuous infusion epidural analgesia during labor: a randomized, double-blind comparison of 0.625% bupivacaine/0.0002% fentanyl versus 0.125% bupivacaine. Anesthesiology 68:754, 1988


Obstentrics_Williams

Obstentrics_Williams. Chestnut DH, Vincent RD Jr, McGrather JM, et al: Does early administration of epidural analgesia afect obstetric outcome in nulliparous women who are receiving intravenous oxytocin? Anesthesiology 80: 1193, 1994b Chisholm ME, Campbell DC: Postpartum postural headache due to superior sagittal sinus thrombosis mistaken for spontaneous intracranial hypotension. Can J Anaesth 48:302,o2001 Craig MG, Grant EN, Tao W, et al: A randomized trial of bupivacaine plus fentanyl versus only fentanyl for epidural analgesia during the second stage of labor. Anesthesiology 122(1):172, 2015 Crawford JS: Some maternal complications of epidural analgesia for labour. Anaesthesia 40: 1219, 1985 Creanga A, Berg q, Syverson C, et al: Pregnancy-related mortality in the United States, 2006-2010. Obstet GynecoIo125(1):5, 2015 Darouiche RO: Spinal epidural abscess. N Engl J Med 355:2012, 2006


Obstentrics_Williams

Obstentrics_Williams. Creanga A, Berg q, Syverson C, et al: Pregnancy-related mortality in the United States, 2006-2010. Obstet GynecoIo125(1):5, 2015 Darouiche RO: Spinal epidural abscess. N Engl J Med 355:2012, 2006 Dashe JS, Rogers BB, McIntire DD, et al: Epidural analgesia and intrapartum fever: placental findings. Obstet Gynecol 93:341, 1999 Davies JM, Posner L, LeeA, et al: Liability associated with obstetric anesthesia: a closed claims analysis. Anesthesiology 10(1):131, 2009 Dawley B, Hendrix A: Intracranial subdural hematoma after spinal anesthesia in a parturient. Obstet Gynecol 113(2):570,2009 Dresner M, Brocklesby J, Bamber J: Audit of the inluence of body mass index on the performance of epidural analgesia in labour and the subsequent mode of delivery. BJOG 113:1178,2006 Eisenach Je, Pan PH, Smiley R, et al: Severity of acute pain after childbirth, but not type of delivety, predicts persistent pain and postpartum depression. Pain 140(1):87,r2008


Obstentrics_Williams

Obstentrics_Williams. Eisenach Je, Pan PH, Smiley R, et al: Severity of acute pain after childbirth, but not type of delivety, predicts persistent pain and postpartum depression. Pain 140(1):87,r2008 Food and Drug Administration: FDA Drug Safety Communication: FDA review results in new warnings about using general anesthetics and sedation drugs in young children and pregnant women. 2016. Available at: http:// www.fda.gov/Drugs/DrugSafety/ucm532356.htm. Accessed February 2, 2017 Friedman EA: Primigravid labor: a graphicostatistical analysis. Obstet Gynecol 6:567, 1955 Fusi L, Steer PJ, Maresh MJA, et al: Maternal pyrexia associated with the use of epidural analgesia in labour. Lancet 1: 1250, 1989 Gambling DR, Sharma SK, Ramin SM, et al: A randomized srudy of combined spinal-epidural analgesia versus intravenous meperidine during labor: impact on cesarean delivery rate. Anesthesiology 89: 1336, 1998


Obstentrics_Williams

Obstentrics_Williams. Glosten B: Local anesthetic techniques. In Chestnut DH (ed): Obstetric Anesthesia: Principles and Practice, 2nd ed. St Louis, Mosby-Year Book, 1999 Grant GJ: Safely giving regional anesthesia to gravidas with clotting disorders. Contemp OB Gyn, August 200 Guglielminotti J, Wong CA, Landau R, et al: Temporal trends in anesthesiarelated adverse events in cesarean deliveries, New York State, 2003-2012. Anesthesiology 123(5): 1013, 2015 Halpern SH, Carvalho B: Patient-controlled epidural analgesia for labor. Anesth Analg 108(3):921,2009 Hannah ME, Whyte H, Hannah J, et al: Maternal outcomes at 2 years after planned cesarean section versus planned vaginal birth for breech presentation at term: the international randomized Term Breech Trial. Am J Obstet Gynecol 191(3):917,r2004 Hatjis CG, Meis PJ: Sinusoidal fetal heart rate pattern associated with butorphanol administration. Obstet Gynecol 67:377, 1986


Obstentrics_Williams

Obstentrics_Williams. Hatjis CG, Meis PJ: Sinusoidal fetal heart rate pattern associated with butorphanol administration. Obstet Gynecol 67:377, 1986 Hawkins JL: Epidural analgesia for labor and delivery. N Engl J Med 362: 1503, 2010 Hawkins JL, Chang J, Palmer SK, et al: Anesthesia-related maternal mortality in the United States: 1979-2002. Obstet GynecoIr117:69, 2011 Hawkins JL, Koonin LM, Palmer SK, et al: Anesthesia-related deaths during obstetric delivety in the United States, 1979-1990. Anesthesiology 86:277, Heesen M, Klahr S, Hofmann T, et al: Maternal and foetal efects of remifentanil for general anaesthesia in parturients undergoing caesarean section: a systematic review and meta-analysis. Acta Anaesthesiol Scand 57(1):29, 2013 Hess PE, Pratt SD, Lucas TP, et al: Predictors of breakthrough pain during labor epidural analgesia. Anesth Analg 93:414, 2001


Obstentrics_Williams

Obstentrics_Williams. Hess PE, Pratt SD, Lucas TP, et al: Predictors of breakthrough pain during labor epidural analgesia. Anesth Analg 93:414, 2001 Hill JB, Alexander JM, Sharma SK, et al: A comparison of the efects of epidural and meperidine analgesia during labor on fetal heart rate. Obstet Gynecol 102:333,r2003 Hogg B, Hauth Je, Caritis SN, et al: Safety of labor epidural anesthesia for women with severe hypertensive disease. m J Obstet Gynecol 181: 1096, 1999 Introna G, Blair JR, Neeld JB: What is the incidence of inadvertent dural puncture during epidural anesthesia in obstetrics? Anesthesiology 117(3):686,r2012 KainuJP, SarvelaJ, Tippana E, et al: Persistent pain after cesarean section and vaginal birth: a cohort study. Int J Obstet Anesth 19(1):4,r2010 Kan RE, Hughes SC, Rosen MA, et al: Intravenous remifentanil: placental transfer, maternal and neonatal effects. Anesthesiology 88(6): 1467, 1998


Obstentrics_Williams

Obstentrics_Williams. Kan RE, Hughes SC, Rosen MA, et al: Intravenous remifentanil: placental transfer, maternal and neonatal effects. Anesthesiology 88(6): 1467, 1998 Katircioglu K, Hasegeli L, Ibrahimhakkioglu HF, et al: A retrospective review of 34, 1 09 epidural anesthetics for obstetric and gynecologic procedures at a single private hospital in Turkey. AnesthrAnalg 107:r1742,r2008 Kennedy F Jr, Bonica J], Akamatsu TJ, et al: Cardiovascular and respiratory efects of subarachnoid block in the presence of acute blood loss. Anesthesiology 29:29, 1968 ing TL, Wong CA: Nitrous oxide for labor pain: is it a laughing matter? Anesth Analg 118(1):12, 2014 Kinsella SM, Winton AL, Mushambi MC, et al: Failed tracheal intubation during obstetric general anaesthesia: a literature review. Int J Obstet Anesth 24(4):356,r2015 Krivak Te, Zorn KK: Venous thromboembolism in obstetrics and gynecology. 61,r2007 Lavoie A, Toledo P: Multimodal postcesarean delivery analgesia. Clin Perinatol 40(3):443,r2013


Obstentrics_Williams

Obstentrics_Williams. Krivak Te, Zorn KK: Venous thromboembolism in obstetrics and gynecology. 61,r2007 Lavoie A, Toledo P: Multimodal postcesarean delivery analgesia. Clin Perinatol 40(3):443,r2013 Lee A, Ngan Kee WD, Gin T: A quantitative, systematic review of randomized controlled trials of ephedrine versus phenylephrine for the management of hypotension during spinal anesthesia for cesarean delivety. Anesth Analg 94:920, 2002a Lee A, Ngan Kee WD, Gin T: Prophylactic ephedrine prevents hypotension during spinal anesthesia for cesarean delivery but does not improve neonatal outcome: a quantitative systematic review. Can J Anaesth 49:588, 2002b Lee A, Posner KL, Domino KB, et al: Injuries associated with regional anesthesia in the 1980s and 1990s: a closed claims analysis. Anesthesiology 101:143,r2004


Obstentrics_Williams

Obstentrics_Williams. Lee A, Posner KL, Domino KB, et al: Injuries associated with regional anesthesia in the 1980s and 1990s: a closed claims analysis. Anesthesiology 101:143,r2004 Li G, Warner M, Lang BH et al: Epidemiology of anesthesia-related mortality in the United States, 1999-2005. Anesthesiology 110(4):759,r2009 Lieberman E, Lang JM, Cohen A, et al: Association of epidural analgesia with cesarean delivery in nulliparas. Obstet Gynecol 88:993, 1996 Lieberman E, O'Donoghue C: Unintended efects of epidural analgesia during labor: a systematic review. Am J Obstet Gynecol 186:531, 2002 Likis FE, Andrews Je, Collins MR, et al: Nitrous oxide for the management of labor pain: a systematic review. Anesth Analg 118(1):153, 2014 Liu SS, Lin Y: Local anesthetics. In Barash , Cullen B, Stoeling R, et al (eds): Clinical Anesthesia, 6th ed. Philadelphia, Lippincott Williams & Wilkins,


Obstentrics_Williams

Obstentrics_Williams. Liu SS, Lin Y: Local anesthetics. In Barash , Cullen B, Stoeling R, et al (eds): Clinical Anesthesia, 6th ed. Philadelphia, Lippincott Williams & Wilkins, Liu x'H, Lin JH, Lin Je, et al: Severe intracranial and intraspinal subarachnoid hemorrhage after lumbar puncture: a rare case report. Am J Emerg Med 26:633, 2008 Lucas MJ, Sharma SK, McIntire DD, et al: A randomized trial oflabor analgesia in women with pregnancy-induced hypertension. Am J Obstet Gynecol 185:970,r2001 Manninen T, Aantaa R, Salonen M, et al: A comparison of the hemodynamic efects of paracervical block and epidural anesthesia for labor analgesia. Acta Anaesthesiol Scand 44:441, 2000 Marik PE: Aspiration pneumonitis and aspiration pneumonia. N Engl J Med 344:665, 2001 McClelland SH, Bogod DG, Hardman JG: Pre-oxygenation and apnoea in pregnancy: changes during labour and with obstetric morbidity in a computational simulation. Anaesthesia 64(4):371, 2009


Obstentrics_Williams

Obstentrics_Williams. McClelland SH, Bogod DG, Hardman JG: Pre-oxygenation and apnoea in pregnancy: changes during labour and with obstetric morbidity in a computational simulation. Anaesthesia 64(4):371, 2009 McDonnell JG, O'Donnell B, Curley G, et al: he analgesic eicacy of transversus abdominis plane block after abdominal s urge ty: a prospective randomized controlled trial. Anesth Analg 104(1):193,r200 Mhyre JM, Riesner MN, Polley LS, et al: A series of anesthesia-related maternal deaths in Michigan, 1985-2003. Anesthesiology 106:1096,r2007 Miller N, Cypher R, Thomas S, et al: Admission pulse pressure is a novel predictor of fetal heart rate abnormalities initial dosing of a labour epidural: a retrospective cohort study. Abstract No. 333. Am J Obstet Gynecol 208(1 Suppl):S149, 2013 Millet L, Shaha S, Bartholomew ML: Rates of bacteriuria in laboring with epidural analgesia: continuous vs intermittent bladder catheterization. Am J Obstet Gynecol 206:316, 2012


Obstentrics_Williams

Obstentrics_Williams. Millet L, Shaha S, Bartholomew ML: Rates of bacteriuria in laboring with epidural analgesia: continuous vs intermittent bladder catheterization. Am J Obstet Gynecol 206:316, 2012 Miro M, Guasch E, Gilsanz F: Comparison of epidural analgesia with combined spinal-epidural for labor: a retrospective study of 6497 cases. Int J Obstet Anesth 17: 15, 2008 Mokri B: The Monro-Kellie hypothesis: application in CSF volume depletion. Neurology 56(12):1746,r2001 Mulroy MF: Systemic toxicity and cardiotoxicity from local anesthetics: incidence and preventive measures. Reg Anesth Pain Med 27:556, 2002 Mushambi MC, Kinsella SM: Obstetric Anaesthetists' Association/Diicult Airway Society diicult and failed tracheal intubation guidelines-the way forward for the obstetric airway. Br J Anaesth 115(6):815,2015 Nandagopal M: Local anesthesia for cesarean section. Tech Reg Anesth Pain Manag 5(1):30,r2001


Obstentrics_Williams

Obstentrics_Williams. Nandagopal M: Local anesthesia for cesarean section. Tech Reg Anesth Pain Manag 5(1):30,r2001 Neal JM, Mulroy MF, Weinberg GL, et al: American Society of Regional Anesthesia and Pain Medicine checklist for managing local anesthetic systemic toxicity: 2012 version. Reg Anesth Pain Med 37(1):16,r2012 Ngan Kee WD, Khaw KS, Ng FF, et al: Prophylactic phenylephrine infusion for preventing hypotension during spinal anesthesia for cesarean delivery. Anesth Analg 98:815,r2004 Noblett K, McKinney A, Kim R: Sheared epidural catheter during an elective procedure. Obstet Gynecol 109:566,r2007 Norris Me, Dewan DM: Preoxygenation for cesarean section: a comparison of rwo techniques. Anesthesiology 62:827, 1985 Ohashi Y, Baghirzada L, Sumikura H, et al: Remifentanil for labor analgesia: a comprehensive review. J Anesth 30(6):1020, 2016


Obstentrics_Williams

Obstentrics_Williams. Ohashi Y, Baghirzada L, Sumikura H, et al: Remifentanil for labor analgesia: a comprehensive review. J Anesth 30(6):1020, 2016 Ohel G, Gonen R, Vaida S, et al: Early versus late initiation of epidural analgesia in labor: does it increase the risk of cesarean section? A randomized trial. m J Obstet Gynecol 194:600, 2006 Osterman MJ, Martin JA: Epidural and spinal anesthesia use during labor, 2008. Nat! Vital Stat Rep 59(5):1, 2011 O'Sullivan G, Liu B, Hart D, et al: Efect of food intake during labour on obstetric outcome: randomised controlled trial. BMJ 338:b784, 2009 Paech MJ, Doherty DA, Christmas T, et al: The volume of blood for epidural patch in obstetrics: a randomized blinded clinical trial. Anesth Analg 13(1):126,r2011 Ramin SM, Gambling DR, Lucas MJ, et al: Randomized trial of epidural versus intravenous analgesia during labor. Obstet Gynecol 83, 1995


Obstentrics_Williams

Obstentrics_Williams. Ramin SM, Gambling DR, Lucas MJ, et al: Randomized trial of epidural versus intravenous analgesia during labor. Obstet Gynecol 83, 1995 Reynolds F, Sharma SK, Seed PT: Analgesia in labour and fetal acid-base balance: a meta-analysis comparing epidural with systemic opioid analgesia. BJOG 109:1344,r2002 Rogers R, Gilson G, Kammerer-Doak D: Epidural analgesia and active management of labor: efects on length of labor and mode of delivery. Obstet Gynecol 93:995, 1999 Rosen /1A: Paracervical block for labor analgesia: a brief historic review. Am J Obstet Gynecol 186:S , 2002 Ruppen W, Derry S, McQuay H, et al: Incidence of epidural hematoma, infection, and neurologic injury in obstetric patients with epidural analgesia/ anesthesia. Anesthesiology 105:394,r2006 Scavone BM: Timing of epidural blood patch: clearing up the confusion. Anaesthesia 70(2):119,r2015


Obstentrics_Williams

Obstentrics_Williams. Scavone BM: Timing of epidural blood patch: clearing up the confusion. Anaesthesia 70(2):119,r2015 Scavone BM, Wong CA, Sullivan JT, et al: Eicacy of a prophylactic epidural blood patch in preventing post dural puncture headache in parturients after inadvertent dural puncture. Anesthesiology 101: 1422, 2004


Obstentrics_Williams

Obstentrics_Williams. Setayesh AR, Kholdebarin AR, Moghadam MS, et al: he Trendelenburg position increases the spread and accelerates the onset of epidural anesthesia for cesarean section. Can J Anaesth 48:890,r2001 Seyb ST, Berka RJ, Socol ML, et al: Risk of cesarean delivery with elective induction of labor at term in nulliparous women. Obstet Gynecol 94:600, 1999 Sharma SK, Alexander JM, Messick G, et al: Cesarean delivery: a randomized trial of epidural analgesia versus intravenous meperidine analgesia during labor in nulliparous women. Anesthesiology 96:546, 2002 Sharma SK, McIntire DD, Wiley J, et al: Labor analgesia and cesarean delivery. An individual patient meta-analysis of nulliparous women. Anesthesiology 100:142,r2004 Sharma SK, Rogers BB, Alexander JM, et al: A randomized trial of the efects of antibiotic prophylaxis on epidural related fever in labor. Anesth Analg 118(3):604,r2014 Sharma SK, Sidawi JE, Ramin SM, et al: Cesarean delivery: a randomized trial of epidural versus


Obstentrics_Williams

Obstentrics_Williams. the efects of antibiotic prophylaxis on epidural related fever in labor. Anesth Analg 118(3):604,r2014 Sharma SK, Sidawi JE, Ramin SM, et al: Cesarean delivery: a randomized trial of epidural versus patient-controlled meperidine analgesia during labor. Anesthesiology 87 :487, 1997 Shearer VE, Jhaveri HS, Cunningham FG: Puerperal seizures after post-dural puncture headache. Obstet Gynecol 85:255, 1995 Smarkusky L, DeCarvalho H, Bermudez A, et al: Acute onset headache complicating labor epidural caused by intrapartum pneumocephalus. Obstet Gynecol 108:795, 2006


Obstentrics_Williams

Obstentrics_Williams. Society for Obstetric Anesthesia and Perinarology: Response to the FDA Med Watch December 16, 2016. 2017. Available at: https://soap.org/asaresponse-fda-soapl-20-17.pd. Accessed February 2,r2017 Sperling JD, Dahlke JD, Sibai BM: Restriction of oral intake during labor: whither are we bound? Am J Obstet GynecoI214(5):592, 2016 Sprigge JS, Harper SJ: Accidental dural puncture and post dural puncture headache in obstetric anaesthesia: presentation and management: a 23-year survey in a district general hospital. Anaesthesia 63:36, 2008 Svancarek W, Chirino 0, Schaefer G Jr, et al: Retropsoas and subgluteal abscesses following paracervical and pudendal anesthesia. JAMA 237:892, 1977 Tao W, Grant EN, Craig MG, et al: Continuous spinal analgesia for labor and delivery: an observational study with a 23-gauge spinal catheter. Anesth Analg 121(5):1290, 2015


Obstentrics_Williams

Obstentrics_Williams. Tao W, Grant EN, Craig MG, et al: Continuous spinal analgesia for labor and delivery: an observational study with a 23-gauge spinal catheter. Anesth Analg 121(5):1290, 2015 Taylor G, Pryse-Davies J: The prophylactic use of antacids in the prevention of the acid pulmonary aspiration syndrome (Mendelson's syndrome). Lancet 1:288, 1966 Teabeaut JR II: Aspiration of gastric contents: an experimental study. Am J Pathol 28:51, 1952 Vallejo Me, Mandell GL, Saba DP, et al: Postdural puncture headache: a randomized comparison of five spinal needles in obstetric patients. Anesth Analg 91:916,r2000 van Veen J], Nokes TJ, Makris M: The risk of spinal haematoma following neuraxial anaesthesia or lumbar puncture in thrombocytopenic individuals. Br J HaematoIr148(I):15, 2010 Vricella LK, Louis JM, Mercer BM, et al: Impact of morbid obesity on epidural anesthesia complications in labor. Am J Obstet Gynecol 205:307, 2011


Obstentrics_Williams

Obstentrics_Williams. Vricella LK, Louis JM, Mercer BM, et al: Impact of morbid obesity on epidural anesthesia complications in labor. Am J Obstet Gynecol 205:307, 2011 Wallace DH, Leveno KJ, Cunningham FG, et al: Randomized comparison of general and regional anesthesia for cesarean delivery in pregnancies complicated by severe preeclampsia. Obstet Gynecol 86: 193, 1995 Waring J, Mahboobi SK, Tyagaraj K, et al: Use of remifentanil for labor analgesia: the good and the bad. Anesth Analg 1 04( 46): 1616, 2007 Webb CA, Weyker PD, Zhang L, et I: Unintentional dural puncture with a Tuohy needle increases risk of chronic headache. Anesth Analg 115(1): 124, 2012 Wong CA: Epidural and spinal analgesia/anesthesia for labor and vaginal delivery. In Chestnut's Obstetrical Anesthesia: Principles and Practice, 5th ed. Philadephia, Saunders, 2014 Wong CA, McCarthy RJ, Sullivan JT, et al: Early compared with late neuraxial analgesia in nulliparous labor induction. Obstet Gynecoirl13(5):1066, 2009


Obstentrics_Williams

Obstentrics_Williams. Wong CA, McCarthy RJ, Sullivan JT, et al: Early compared with late neuraxial analgesia in nulliparous labor induction. Obstet Gynecoirl13(5):1066, 2009 Wong CA, Scavone BM, Peaceman AM, et al: The risk of cesarean delivery with neuraxial analgesia given early versus late in labor. N Engl J Med 352:655, 2005 Young MJ, Gorlin AW, Modes VE, et al: Clinical implications of the transversus abdominis plane block in adults. Anesthesiol Res Pract 2012:731645,r2012 Zeeman GG, Cunningham FG, Pritchard JA: The magnitude of hemoconcentration with eclampsia. Hypertens Preg 28(2): 127, 2009 Induction and Augmentation of labor LABOR INDUCTION ......e...........e......e....e. 503 PREINDUCTION CERVICAL RIPENING ..e....e.....e.... 505 PHARMACOLOGICAL TECHNIQUESe. . . . . . . . . . . . . . . . 506 MECHANICAL TECHNIQUES .e........e....e...e..e... 507 METHODS OF INDUCTION AND AUGMENTATION . .. 508 PROSTAGLANDIN E, .. .......... ......... .... 508


Obstentrics_Williams

Obstentrics_Williams. MECHANICAL TECHNIQUES .e........e....e...e..e... 507 METHODS OF INDUCTION AND AUGMENTATION . .. 508 PROSTAGLANDIN E, .. .......... ......... .... 508 OXYTOCIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 509 AMNIOTOMY FOR INDUCTION AND AUGMENTATION . 511 In other cases, if inteerence becomes imperative, the introduction of a bougie into the uterus, or the employment of a smal Champetier de Ribes rubber bag acts as an eective uterine irritant and brings about complete dilatation. -J. No efective means of labor induction were available when Williams wrote the first edition of this book. Labor augmentation methods were largely inefective, and manual cervical dilation was performed as a last resort. Contrast with today, when several pharmacological agents permit labor induction or augmentation, and ironically the use of a "bougie" has come back into vogue.


Obstentrics_Williams

Obstentrics_Williams. Induction implies stimulation of contractions before the spontaneous onset of labor, with or without ruptured membranes. When the cervix is closed and unefaced, labor induction will often commence with cervical ripening, a process that generally employs prostaglandins to soften and open the cervix. Augmentation refers to enhancement of spontaneous contractions that are considered inadequate because of failed cervical dilation and fetal descent-inertia uteri-as described by Williams (1903).


Obstentrics_Williams

Obstentrics_Williams. Augmentation refers to enhancement of spontaneous contractions that are considered inadequate because of failed cervical dilation and fetal descent-inertia uteri-as described by Williams (1903). In the United States, the incidence ofilabor induction rose 2.5-fold from 9.5 percent in 1991 to 23.8 percent in 2015 (Martin, 2017). he incidence varies between practices. At Parkland Hospital, approximately 35 percent of labors are induced or augmented. By comparison, at the University of Alabama at Birmingham Hospital, labor is induced in approximately 20 percent of women, and another 35 percent are given oxytocin for augmentation-a total of 55 percent. This chapter discusses indications for labor induction and augmentation and various techniques to efect preinduction cervical ripening.


Obstentrics_Williams

Obstentrics_Williams. Induction is indicated when the beneits to either mother or fetus outweigh those of pregnancy continuation. The more common indications include membrane rupture without labor, gestational hypertension, oligohydramnios, nonreassuring fetal status, postterm pregnancy, and various maternal medical conditions such as chronic hypertension and diabetes (American College of Obstetricians and Gynecologists, 20i16). Methods to induce or augment labor are contraindicated by most conditions that preclude spontaneous labor or delivelY. The few maternal contraindications are related to prior uterine incision type, contracted or distorted pelvic anatomy, abnormally implanted placentas, and uncommon conditions such as active genital herpes infection or cervical cancer. Fetal factors include appreciable macrosomia, severe hydrocephalus, malpresentation, or nonreassuring fetal status.


Obstentrics_Williams

Obstentrics_Williams. Oxytocin has been used for decades to induce or augment labor. Other efective methods include prostaglandins, such as misoprostol and dinoprostone, and mechanical methods that encompass membrane stripping, artiicial rupture of membranes, extraamnionic saline infusion, transcervical balloons, and hygroscopic cervical dilators. Importantly, and as recommended in Guidelines or Perinatal Care, each obstetrical department should have its own written protocols that describe administration of these methods for labor induction and augmentation (American Academy of Pediatrics, 2017).


Obstentrics_Williams

Obstentrics_Williams. Maternal complications associated with labor induction are cesarean delivery, chorioamnionitis, uterine rupture, and postpartum hemorrhage from uterine atony. Of these, labor induction carries a two-to threefold greater risk for cesarean delivery (Hofman, 2003; Maslow, 2000; Smith, 2003). his risk is particularly higher among nulliparas (Luthy, 2004; Wolfe, 2014; Yeast, 1999). More recently, this association has been questioned (Macones, 2009; Melamed, 2016; Miller, 2015; Saccone, 2015). Indeed, Darney and colleagues (2012) reported the cesarean delivery risk was actually lower for women with labor induction at 39 weeks' gestation compared with that in women expectantly managed. In their review, Little and Caughey (2015) found a reduced cesarean delivery rate when women undergoing labor induction were compared with women expectantly managed, as opposed to women spontaneously laboring. Currently, this is the topic of a randomized trial by the 1aternal-Fetal Medicine Units (MFMU)


Obstentrics_Williams

Obstentrics_Williams. induction were compared with women expectantly managed, as opposed to women spontaneously laboring. Currently, this is the topic of a randomized trial by the 1aternal-Fetal Medicine Units (MFMU) NetworkA Randomized Trial of Induction Versus Expectant v1anagement-ARRIVE (National Institutes of Health, 2015).


Obstentrics_Williams

Obstentrics_Williams. Amniotomy is often selected to augment labor (p. 511). Women whose labor is managed with amniotomy have a higher incidence of chorioamnionitis compared with those in spontaneous labor (American College of Obstetricians and Gynecologists, 2016). Rupture of a prior uterine incision during labor in women with a history of prior uterine surgery can be catastrophic (Chap. 31, p. 598). The MFMU Network reported a threefold greater risk of uterine scar rupture with oxytocin, and this was even higher with prostaglandin use (Landon, 2004). he American College of Obstetricians and Gynecologists (20 17b) recommends against the use of prostaglandins for preinduction cervical ripening or labor induction in women with a prior uterine incision.


Obstentrics_Williams

Obstentrics_Williams. Uterine atony and associated postpartum hemorrhage are more common in women undergoing induction or augmentation (Chap. 41, p. 759). And, atony with intractable hemorrhage, especially during cesarean delivery, is a frequent indication for peripartum hysterectomy. In a study from Parkland Hospital, labor induction was associated with 17 percent of 553 emergency peripartum hysterectomies (Hernandez, 2013). In the United States, the postpartum hysterectomy rate rose 15 percent between 1994 and 2007 (Bateman, 2012). his was largely attributed to increased rates of atony associated with more medical labor inductions and more primary and repeat cesarean deliveries. In another analysis, elective induction was also linked with a threefold higher rate of hysterectomy (Bailit, 2010).


Obstentrics_Williams

Obstentrics_Williams. Until recently, elective induction for convenience had become increasingly prevalent. Clark and coworkers (2009) described 14,955 deliveries at �37 weeks' gestation. hey noted that 32 percent were elective deliveries, and 19 percent were elective labor inductions.


Obstentrics_Williams

Obstentrics_Williams. he American College of Obstetricians and Gynecologists (2016) does not endorse this once widespread practice. Occasional exceptions might include logistical and other reasons such as a risk of rapid labor, a woman who lives a long distance from the hospital, or psychosocial indications. Because of the greater risks for adverse maternal outcomes, we are also of the opinion that routine elective induction at term is not justified. Elective delivery before 39 completed weeks is also associated with signiicant adverse neonatal morbidity (Chiossi, 2013; Clark, 2009; Salemi, 2016; Tita, 2009). If elective induction is considered at term, inherent risks must be discussed, informed consent obtained, and guidelines followed as promulgated by the American College of Obstetricians and Gynecologists (2016), which are detailed in Chapter 31 (p. 597).


Obstentrics_Williams

Obstentrics_Williams. Guidelines to discourage elective inductions have been described by Fisch (2009) and Oshiro (20l3) and their associates. Both groups reported signiicant declines in elective delivery rates following guideline initiation. In 201i1, the Texas Medicaid program began to deny payment for elective induction prior to 39 weeks' gestation. his resulted in a 14-percent drop in such early-term deliveries and a rise in birthweights (Dahlen, 2017). A program in Oregon also reduced early-term deliveries, but maternal and fetal outcomes were not improved (Snowden, 2016).


Obstentrics_Williams

Obstentrics_Williams. Several factors afect the ability of labor induction to achieve vaginal delivery. Favorable factors include younger age, multiparity, body mass index (BMI) <30, favorable cervix, and birthweight <3500 g (Gibson, 2015; Roland, 2017; Sievert, 2017). In many cases, the uterus is simply poorly prepared for labor. One example is an "unripe cervix." Indeed, investigators with the Consortium on Sae Labor reported that elective induction resulted in vaginal delivery in 97 percent of multiparas and 76 percent of nulliparas, but that induction was more often successful with a ripe cervix (Laughon, 2012).


Obstentrics_Williams

Obstentrics_Williams. he greater cesarean delivery risk associated with induction is likely also strongly influenced by the induction attempt duration, especially with an unfavorable cervix (Spong, 2012). In one study, labor duration to reach the active phase and to complete dilation was adversely afected by a higher BMI (Kominiarek, 2011). Similar indings were reported for women with diabetes (Hawkins, 2017). Simon and Grobman (2005) concluded that a latent phase as long as 18 hours allowed most women undergoing labor induction to achieve a vaginal delivery without a signiicantly increased risk of maternal or neonatal morbidity. Rouse and associates (2000) recommend a minimum of Induction and Augmentation of Labor 505 TABLE 26-1 . Some Commonly Used Regimens for Preinduction Cervical Ripening and/or Labor Induction Prostaglandin E2 Oinoprostone gel, Cervical 0.5 mg; repeat in 1. Shorter 1-0 times with oxytocin infusion 0.5 mg (Prepidil) 6 hr; permit 3 doses total than oxytocin alone


Obstentrics_Williams

Obstentrics_Williams. Prostaglandin E2 Oinoprostone gel, Cervical 0.5 mg; repeat in 1. Shorter 1-0 times with oxytocin infusion 0.5 mg (Prepidil) 6 hr; permit 3 doses total than oxytocin alone Oinoprostone insert, Posterior 10 mg 1. Insert has shorter 1-0 times than gel 10 mg (Cervidil) 2. 6-12 hr interval from last insert to oxytocin aOf-label use. bTablets must be divided for 25-and 50-�g dose, but drug is evenly dispersed. EASI = extraamnionic saline infusion at 30-40 mUhr; 1-0 = induction-to-delivery. 12 hours of uterine stimulation with oxytocin after membrane rupture, whereas Kawakita and coworkers (2016) recommend up to 15 hours for multiparas. As discussed, the condition of the cervix-described as cervical "ripeness" or "favorability"-is important to successful labor induction. However, at least some estimates of favorability are highly subjective (Peltovich, 2017). hat said, pharmacological and mechanical methods can enhance cervical favorabilityalso termed preinduction cervical ripening.


Obstentrics_Williams

Obstentrics_Williams. Some of the techniques described may have benefits when compared with oxytocin induction alone (Table Some are also quite successful for initiating labor. However, few data support the premise that any of these techniques lower cesarean delivery rates or lessen maternal or neonatal morbidity compared with women in whom these methods are not used. One quantifiable method used to predict labor induction outcomes is the score described by Bishop (1964) and presented in Table 26-2. As favorability or Bishop score declines, the rate of induction to efect vaginal delivery also decreases. A Bishop score of 9 conveys a high likelihood for a successful induction. Por research purposes, a Bishop score of 4 or less identifies an unfavorable cervix and may be an indication for cervical ripening. TABLE 26-2. Bishop Scoring System Used for Assessment of Inducibility Score Dilatation (cm) Efacement (%) Station (-3 to +2) Consistency Position �80 +1, +2 From Bishop, 1964.


Obstentrics_Williams

Obstentrics_Williams. TABLE 26-2. Bishop Scoring System Used for Assessment of Inducibility Score Dilatation (cm) Efacement (%) Station (-3 to +2) Consistency Position �80 +1, +2 From Bishop, 1964. Laughon and coworkers (201i1) attempted to simpliy the Bishop score by performing a regression analysis on 5610 singleton, uncomplicated deliveries between 37°/7 and 416/7 weeks' gestation in nulliparas. Only cervical dilation, station, and efacement were signiicantly associated with successful vaginal delivery. hus, a simplified Bishop score, which incorporated only these three parameters, had a similar or improved positiveor negative-predictive value compared with that of the original Bishop score. Other investigators have reported similar findings when consistency and position are omitted (Ivars, 2016; Raghuraman,i2016).


Obstentrics_Williams

Obstentrics_Williams. Transvaginal sonographic measurement of cervical length is the only biophysical marker that has been evaluated as a Bishop score alternative (Feltovich, 2017). In one metaanalysis of trials in which cervical length was used to predict successful induction, study criteria heterogeneity precluded the authors from reaching a summary answer (Hatfield, 2007). A subsequent metaanalysis of 31 trials found overall low sensitivity and speciicity and limited predictive utility for sonographic cervical length and "wedging" to predict successful labor induction (Verhoeven, 2013). Unfortunately, women frequently have an indication for induction but also have an unfavorable cervix. Several techniques are available, and these can also stimulate contractions and thereby aid subsequent labor induction or augmentation. Methods most commonly used for preinduction cervical ripening and induction include several prostaglandin analogues.


Obstentrics_Williams

Obstentrics_Williams. Dinoprostone is a synthetic analogue of prostaglandin E2 (PGE2). It is commercially available in three forms: a gel, a timerelease vaginal insert, and a 20-mg suppository (Table 26-1). he gel and time-release vaginal insert formulations are indicated only for cervical ripening before labor induction. However, the 20-mg suppository is not indicated for cervical ripening. It instead is used for pregnancy termination between 12 and 20 weeks' gestation and for evacuation of the uterus after fetal demise up to 28 weeks. Local application of its gel form-Prepidil-is available in a 2.5-mL syringe for an intracervical application of 0.5 mg of dinoprostone. With the woman supine, the tip of a prefilled syringe is placed intracervically, and the gel is deposited just below the internal cervical os. After application, the woman remains reclined for at least 30 minutes. Doses may be repeated every 6 hours, with a maximum of three doses recommended in 24 hours.


Obstentrics_Williams

Obstentrics_Williams. A 10-mg dinoprostone vaginal insert-Cervidil-is also approved for cervical ripening. This is a thin, flat, rectangular polymeric wafer held within a small, white, mesh polyester sac (Fig. 26- The sac has a long attached tail to allow easy removal from the vagina. The insert provides slower release of medication-0.3 mg/hr-than the gel form. Cervidil is used as a single dose placed transversely in the posterior vaginal fornix. Lubricant is used sparingly, if at all, because it can coat the device and hinder dinoprostone release. Following insertion, the woman remains recumbent for at least 2 hours. he insert is removed after 12 hours or with labor onset and at least 30 minutes before the administration of oxytocin. FIGURE 26-1 Cervidil vaginal insert contains 10 mg of dinoprostone designed to release approximately OJ mg/hr during a1 O-hour period.


Obstentrics_Williams

Obstentrics_Williams. Most metaanalyses of dinoprostone eicacy report a reduced time-to-delivery within 24 hours, however, they do not consistently show a reduction in the cesarean delivery rate. Thomas and colleagues (2014) provided a Cochrane review of 70 trials and 11i,487 women given vaginal prostaglandins or either placebo or no treatment. They noted a higher vaginal delivery rate within 24 hours when prostaglandins were used. hey also reported a threefold greater risk of tachysystole accompanied by fetal heart rate changes, but cesarean delivery rates were not signiicantly decreased. Similar results were noted in another Cochrane review of intracervical dinoprostone gel (Boulvain, 2008). Compared with placebo or no treatment, a reduced risk of cesarean delivery was found only in a subgroup of women with an unfavorable cervix and intact membranes. Finally, the Foley catheter versus vaginal PGE2 gel for induction of labor at term-PROBAAT-P and -M trials-were un blinded, randomized trials comparing


Obstentrics_Williams

Obstentrics_Williams. an unfavorable cervix and intact membranes. Finally, the Foley catheter versus vaginal PGE2 gel for induction of labor at term-PROBAAT-P and -M trials-were un blinded, randomized trials comparing these two options Qozwiak, 2011, 2013, 2014). he cesarean delivery rate did not difer, a inding consistent with accompanying metaanalyses.


Obstentrics_Williams

Obstentrics_Williams. Side Efects. Uterine tachysystole follows vaginally administered PGE2 in 1 to 5 percent of women (Hawkins, 2012). Although deinitions of abnormal uterine activity vary among studies, most use the definition recommended by the American College of Obstetricians and Gynecologists (2017a): 1. Uterine tachysystole is deined as > 5 contractions in a 10-minute period. It should always be qualiied by the presence or absence of fetal heart rate abnormalities. 2. Uterine hypertonus, hyperstimulation, and hypercontractiliy are terms no longer deined, and their use is not recommended. Because uterine tachysystole associated with fetal compromise may develop when prostaglandins are used with preexisting spontaneous labor, such use is not recommended. If tachysystole follows the 10-mg insert, its removal by pulling on the tail of the surrounding net sac will usually reverse this efect. Irrigation to remove the gel preparation has not been shown to be helpful.


Obstentrics_Williams

Obstentrics_Williams. The manufacturers recommend caution when these preparations are used in women with ruptured membranes. This concern is also extended to women with glaucoma or asthma. However, in a review of 189 women with asthma, dinoprostone was not associated with asthma worsening or exacerbation (Towers, 2004). Other contraindications listed by the manufacturers include a history of dinoprostone hypersensitivity, suspicion of fetal compromise or cephalopelvic disproportion, unexplained vaginal bleeding, women already receiving oxytocin, those with six or more previous term pregnancies, those with a contraindication to vaginal delivery, or women with a contraindication to oxytocin or who may be endangered by prolonged uterine contractions, for example, those with a history of cesarean delivery or uterine surgery.


Obstentrics_Williams

Obstentrics_Williams. Administration. PGE2 preparations should only be administered in or near the delivery suite. Moreover, uterine activity and fetal heart rate should be monitored (American College of Obstetricians and Gynecologists, 2016). These guidelines stem from the risk of uterine tachysystole. When contractions begin, they are usually apparent in the irst hour and show peak activity in the irst 4 hours. According to manufacturer guidelines, oxytocin induction that follows prostaglandin use for cervical ripening should be delayed for 6 to 12 hours following PGE2 gel administration or for at least 30 minutes after removal of the vaginal insert. Prostaglandin E,


Obstentrics_Williams

Obstentrics_Williams. Prostaglandin E, Misoprostol-Cytotec-is a synthetic prostaglandin EI (PGE1) that is approved as a 100-or 200-�g tablet for peptic ulcer prevention. It has been used "of label" for preinduction cervical ripening and may be administered orally or vaginally. he tablets are stable at room temperature. Although widespread, the of-label use of misoprostol has been controversial (Wagner, 2005; Weeks, 2005). Specifically, G. D. Searle & Company notiied physicians that misoprostol is not approved for labor induction or abortion (Cullen, 2000). Still, the American College of Obstetricians and Gynecologists (2016) reairmed its recommendation for use of the drug because of proven safety and eicacy. It currently is the preferred prostaglandin for cervical ripening at Parkland Hospital. In one review of 234 women administered misoprostol, no instances of asthma exacerbation were associated with its use, and the risk of this was calculated to be <2 percent (Rooney Thompson, 2015).


Obstentrics_Williams

Obstentrics_Williams. Vaginal Administration. Compared with intracervical or intravaginal PGE2, vaginally administered misoprostol tablets ofer equivalent or superior eicacy for cervical ripening or labor induction. A metaanalysis of 121 trials also conirmed these indings (Hofmeyr, 2010). Compared with oxytocin or with intravaginal or intracervical dinoprostone, vaginal misoprostol increased the vaginal delivery rate within 24 hours. In this review, although the uterine tachysystole rate rose, this did not afect cesarean delivery rates. Moreover, compared with dinoprostone, misoprostollowered the need for oxytocin induction,


Obstentrics_Williams

Obstentrics_Williams. Induction and Augmentation of Labor 507 but it increased the frequency of meconium-stained amni onic fluid. Higher doses of misoprostol are associated with a decreased need for oxytocin but with more uterine tachysystole, with and without fetal heart rate changes. The American Col lege of Obstetricians and Gynecologists (2016) recommends a 25-�g vaginal dose-a fourth of a 1 OO-�g tablet. he drug is evenly distributed among these quartered tablets. Wing and colleagues (2013) described use of a vaginal polymer insert containing 200 �g of PGE1• hey compared its eicacy with 10-mg dinoprostone inserts, and preliminary observations are favorable.


Obstentrics_Williams

Obstentrics_Williams. Oral Administration. PGE1 tablets are also efective when given orally. One Cochrane metaanalysis of76 trials reported that oral misoprostol compared with placebo signiicantly raised the rate of vaginal birth within 24 hours, while decreasing the need for oxytocin and lowering the cesarean delivery rate. Comparisons of oral misoprostol and oxytocin and of oral misoprostol and dinoprostone also found signiicantly reduced rates of cesarean delivery with misoprostol. Similar eicacy was noted between oral misoprostol and vaginal administration, although oral administration was associated with significantly higher Apgar scores and less postpartum hemorrhage (Alirevic, 2014). Thorbionson and associates (2017) also reported lower rates of cesarean delivery for oral misoprostol compared with vaginal dinoprostone.


Obstentrics_Williams

Obstentrics_Williams. stimulate nitric oxide (NO) production locally (Chanrachakul, 2000). First, NO is likely a mediator of cervical ripening. Also, cervical NO metabolite concentrations are increased at the beginning of uterine contractions. And, cervical NO produc tion is very low in postterm pregnancy (Vaisanen-T ommiska, 2003, 2004).


Obstentrics_Williams

Obstentrics_Williams. Bullarbo and colleagues (2007) reviewed rationale and use of two NO donors, isosorbide mononitrate and gyceyl trinitrate. Isosorbide mononitrate induces cervical cyclooxygenase 2 (COX-2), and it also initiates cervical ultrastructure rearrangement similar to that seen with spontaneous cervical ripening (Ekerhovd, 2002, 2003). Despite this, NO donors are less efective clinically than prostaglandins, either PGE2 or misoprostol, for cervical ripening. In one large metaanalysis, the rate of cesarean delivery was not reduced in those given NO donors compared with those given placebo, intravaginal or intracervical prostaglandins, intravaginal misoprostol, or intracervical catheter (Ghosh, 2016). However, NO donors were associated with signiicantly more headaches, nausea, and vomiting.


Obstentrics_Williams

Obstentrics_Williams. These include transcervical placement of a Foley catheter, with or without extraamnionic saline infusion; hygroscopic cervical dilators; and membrane stripping. In their metaanalysis, Jozwiak and associates (2012) reported that mechanical techniques reduced the risk of uterine tachysystole compared with prostaglandins, although cesarean delivery rates were unchanged. Trials comparing mechanical techniques with oxytocin found a lower rate of cesarean delivery with mechanical methods. Trials comparing mechanical techniques with dinoprostone found a higher rate of multiparas undelivered at 24 hours with mechanical techniques. In another metaanalysis comparing Foley catheter placement with intravaginal dinoprostone inserts, rates of cesarean delivery were similar, but uterine tachysystole was less frequent with catheter use Qozwiak, 2013).


Obstentrics_Williams

Obstentrics_Williams. Generally, these techniques are only used when the cervix is unfavorable because the catheter tends to come out as the cervix opens. It is suitable for women with intact or ruptured membranes. In most cases, a Foley catheter is placed through the internal cervical os, and downward tension is created by taping the catheter to the thigh (Mei-Dan, 2014). A modification of this-extraamnionic saline inusion (EASI}-adds a constant saline infusion through the catheter into the space between the internal os and placental membranes (Fig. 26-2). Karjane and coworkers (2006) reported that chorioamnionitis was signiicantly less frequent when infusion was done compared with no infusion-6 versus 16 percent. Similarly, in a large metaanalysis, trans cervical catheters were not associated with higher rates of maternal or fetal infection (McMaster, 2015).


Obstentrics_Williams

Obstentrics_Williams. As discussed above, transcervical catheters do not reduce the cesarean delivery rate compared with prostaglandins. The PROBAAT trials (-I, -P, -M, and II), in which cervical ripening with a Foley catheter was compared with vaginal dinoprostone gel, dinoprostone vaginal inserts, and vaginal or oral misoprostol, reported similar outcomes between the mechanical technique and the prostaglandin agents. Also, fewer overall cases of cardiotocographic changes were seen in the mechanical technique group Qozwiak, 2011, 2013, 2014; Ten Eikelder, 2016). FIGURE 26-2 Extraamnionic saline infusion (EASI) through a 26F Foley catheter that is placed through the cervix. The 30-mL balloon is inflated with saline and pulled snugly against the internal os, and the catheter is taped to the thigh. Room-temperature normal saline is infused through the catheter port of the Foley at 30 or 40 mUhour by intravenous infusion pump.


Obstentrics_Williams

Obstentrics_Williams. Similar cesarean delivery rate results are found in other comparison studies. Schoen and coworkers (2017) observed that concurrent oxytocin with a transcervical Foley catheter shortened the median time-to-delivery compared with a Foley catheter followed by oxytocin. However, rates of cesarean delivery were unchanged. Connolly and associates (2016) reported similar findings for women within intact membranes undergoing labor induction. Amorosa and colleagues (2017) found no beneit for transcervical catheter coupled with oxytocin compared against oxytocin alone for women with ruptured membranes. Other studies of concurrent misoprostol reported reduced timeto-delivery without afecting cesarean delivey rates (Carbone, 2013; Levine, 2016). Finally, the concurrent addition of tension does not appear to enhance catheter eicacy. Fruhman and coworkers (2017) randomized 140 women to trans cervical Foley catheter with and without tension, and reported similar vaginal delivery rates within 24


Obstentrics_Williams

Obstentrics_Williams. appear to enhance catheter eicacy. Fruhman and coworkers (2017) randomized 140 women to trans cervical Foley catheter with and without tension, and reported similar vaginal delivery rates within 24 hours or overall.


Obstentrics_Williams

Obstentrics_Williams. Cervical dilation can be accomplished using hygroscopic osmotic cervical dilators, as described for early pregnancy termination (Chap. 18, p. 358). Intuitive concerns of ascending infection have not been veriied, and their use appears to be safe. Placement generally requires a speculum and positioning of the woman on an examination table. Several studies performed in the 1990s compared hygroscopic cervical dilators and prostaglandins and found few benefits of this mechanical technique. And, more recent studies veriied these conclusions (Maier, 2017).


Obstentrics_Williams

Obstentrics_Williams. Labor induction has primarily been efected with the use of amniotomy, prostaglandins, and oxytocin, alone or in combination. Because preinduction cervical ripening frequently eventuates in labor, studies to determine induction eicacy for some of these agents have produced sometimes confusing results. he use of prostaglandins for labor augmentation has generally been considered experimental due to their high rates of uterine tachysystole. • Prostaglandin E,


Obstentrics_Williams

Obstentrics_Williams. Both vaginal and oral misoprostol are used for either cervical ripening or labor induction. For labor induction in women at or near term with either prematurely ruptured membranes or a favorable cervix, 100 I1g of oral or 25 1g of vaginal misoprostol has similar eicacy compared with intravenous oxytocin. From these studies, evidence supports that oral misoprostol may be superior (Alirevic, 2014; Hofmeyr, 2010; Lo, 2003). Misoprostol may be associated with a greater rate of uterine tachysystole, particularly at higher doses. Also, induction with PGEI may prove inefective and require subsequent induction or augmentation with oxtocin. hus, although there are trade-ofs regarding the risks, costs, and ease of administration of each drug, either is suitable for labor induction. At Parkland Hospital, we administer an initial oral 100-l1g dose, which may be repeated ater 6 hours for inadequate labor. Six hours ater the second dose or in those with tachysystole, an oxytocin infusion is begun,


Obstentrics_Williams

Obstentrics_Williams. we administer an initial oral 100-l1g dose, which may be repeated ater 6 hours for inadequate labor. Six hours ater the second dose or in those with tachysystole, an oxytocin infusion is begun, if needed, for hypotonic labor. Dobert and colleagues (2017) have described preliminary use of a misoprostol vaginal insert.