Obstentrics_Williams

Obstentrics_Williams. The incidence of uterine inversion ranges from 1 in 2000 to 1 in 20,000 vaginal deliveries (Coad, 2017; Ogah, 2011; Rana, 2009; Witteveen, 2013). Our experiences at Parkland Hospital comport with the higher 1 :2000 incidence. his is despite our policy of discouraging placental delivery by cord traction alone, and before certainty of its separation. It is unknown if active management o/third-stage labor with cord traction applied ostensiblyater signs of placental separation raises the likelihood of uterine inversion (Deneux-Tharaux, 2013; Gulmezoglu, 2012; Prick, 2013). Immediate recognition of uterine inversion improves the chances of a quick resolution and good outcome (Furukawa, 20 15b). If initially unrecognized, continued hemorrhage likely FIGURE 41-6 Progressive degrees of uterine inversion. FIGURE 41 -9 Surgical anatomy of a completely inverted uterus viewed from above at laparotomy.


Obstentrics_Williams

Obstentrics_Williams. FIGURE 41-6 Progressive degrees of uterine inversion. FIGURE 41 -9 Surgical anatomy of a completely inverted uterus viewed from above at laparotomy. In some cases, the uterus will again invert almost immediately after repositioning. With this problem, uterine compression sutures can be used to prevent another inversion (Matsubara, 2009; Mondal, 2012). Occasionally, chronic puerperal uterine inversion may become apparent weeks after delivery. Childbirth is invariably associated with trauma to the birth canal, which includes the uterus and cervix, vagina, and perineum. Injuries sustained during labor and delivery range from minor mucosal tears to lacerations that create life-threatening hemorrhage or hematomas. According to the American College of Obstetricians and Gynecologists (2016b), up to 80 percent of women sustain some type of laceration at vaginal delivery. hese may lie proximally or distally along the lower genital tract.


Obstentrics_Williams

Obstentrics_Williams. First, small tears of the anterior vaginal wall near the urethra are relatively common. hey are often supericial with little to no bleeding, but they occasionally require sutures for hemostasis. Those large enough to require extensive repair are typically associated with short-term voiding diiculty, and an indwelling bladder catheter will obviate this. Deeper perineal lacerations are usually accompanied by varying degrees of injury to the outer third of the vaginal vault. Some extend to involve the anal sphincter or varying depths of the vaginal walls. Repair of these perineal lacerations is detailed in Chapter 27 (p. 531).


Obstentrics_Williams

Obstentrics_Williams. Lacerations involving the middle or upper third of the vaginal vault usually are comorbid with injuries of the perineum or cervix. hese sometimes are missed unless inspection is thorough. Those that extend upward usually are longitudinal. They may follow spontaneous delivery but frequently result from injries sustained during operative vaginal delivery. Most niicant hemorrhage, which is controlled by suture repair. For this, efective analgesia or anesthesia, clear visualization, capable assistance, and suicient resuscitation of hypovolemia are man datory. search for evidence of retroperitoneal hemorrhage or of perito neal perforation with hemorrhage. Also, intrauterine explora tion is considered to exclude uterine tears or rupture (Conrad, 2015). If peritoneal perforation or uterine rupture is strongly suspected, laparotomy is considered (Rai, 2010). As discussed later (p. 793), imaging and potential embolization may be suit able for large retroperitoneal hematomas.


Obstentrics_Williams

Obstentrics_Williams. Supericial lacerations of the cervix can be seen on close inspec tion in more than half of all vaginal deliveries. Most of these measure <0.5 cm and seldom require repair. Deeper lacera tions are less frequent, but even these may be unnoticed. Due to ascertainment bias, variable incidences are described. For example, with close inspection, the incidence of cervical lacera tions in the Consortium on Safe Labor database was 1 percent in nulliparas and 0.5 percent in multiparas (Landy, 2011). But, the overall incidence in a study of more than 81 ,000 Israeli women was only 0.16 percent (Melamed, 2009). Such lacera tions are more likely to be associated with vacuum-or forceps assisted vaginal delivery (Fong, 2014).


Obstentrics_Williams

Obstentrics_Williams. Cervical lacerations are not usually problematic unless they cause hemorrhage or extend to the vagina. Rarely, the cervix may be entirely or partially avulsed from the vagina in the anterior, posterior, or lateral fornices, an injury termed coporrhxis. Another rare injury is when the entire vaginal portion of the cervix is avulsed-annular or circular detachment. These injuries sometimes follow forceps deliveries performed through an incompletely dilated cervix with the blades applied over the cer vix. In some women, cervical tears reach into the lower uterine segment and involve the uterine artery and its major branches. They occasionally extend into the peritoneal cavity. More severe lacerations usually manifest as external hemorrhage or as a hematoma, however, they may occasionally be unsuspected. In the Israeli study just cited, almost 11 percent of women with a cervical laceration required blood transfusions (Melamed, 2009).


Obstentrics_Williams

Obstentrics_Williams. At times, the edematous anterior cervical lip is compressed berween the fetal head and maternal symphysis pubis. This usually is of little consequence and resolves spontaneously. Rarely, this causes severe ischemia, and the anterior lip may undergo necrosis and subsequently separate from the rest of the cervix. As with vulvovaginal lacerations, cervical tears can be more fully appreciated with adequate exposure, which may be best attained with transfer to an operating room. An assistant applies irm downward pressure on the uterus, while the operator exerts gentle traction on the lips of the cervix with ring forceps. A second assistant can provide even better exposure with right-angle vaginal wall retractors or Breisky vaginal retractors. Use of suction devices can also aid viewing.


Obstentrics_Williams

Obstentrics_Williams. In general, cervical lacerations of 1 and even 2 cm are not repaired unless they are bleeding. Such tears heal rapidly and ultimately create an irregular, sometimes stellate appearing, external cervical os that indicates previous delivery. FIGURE 41 -10 Repair of cervical laceration with appropriate surgical exposure. Continuous absorbable sutures are placed beginning at the upper angle of the laceration.


Obstentrics_Williams

Obstentrics_Williams. FIGURE 41 -10 Repair of cervical laceration with appropriate surgical exposure. Continuous absorbable sutures are placed beginning at the upper angle of the laceration. Deep cervical tears usually require surgical repair. When the laceration is limited to the cervix or even when it extends somewhat into the vaginal fornix, satisfactory results are obtained by suturing the cervix after bringing it into view as depicted in Figure 41-10. While cervical lacerations are repaired, any associated vaginal lacerations or an episiotomy may be tamponaded with gauze packs to arrest their bleeding. Because hemorrhage usually comes from the upper angle of the wound, the first suture using 2-0 chromic or polyglactin is placed in tissue above the angle. Subsequently, either interrupted or continuous locking sutures are serially placed outward toward the operator. If the uterus is involved and hemorrhage persists, some of the methods described later (p. 792) may be necessary to obtain hemostasis.


Obstentrics_Williams

Obstentrics_Williams. Pelvic hematomas can have several anatomical manifestations following childbirth. One classification is anatomical and describes vulvar, vulvovaginal, paravaginal, and retroperitoneal hematomas. Vulvar hematomas may involve the vestibular bulb or branches of the pudendal artery, which are the inferior rectal, perineal, and clitoral arteries (Fig. Paravaginal hematomas may involve the descending branch of the uterine artery. In some cases, a torn vessel lies above the pelvic fascia, and a supralevator hematoma develops. These can extend into the upper portion of the vaginal canal and may almost occlude its lumen. Continued bleeding may dissect retroperitoneally to form a mass palpable above the inguinal ligament. In some cases, it may even dissect up behind the ascending colon to the hepatic flexure (Rai, 2010).


Obstentrics_Williams

Obstentrics_Williams. Risks for puerperal hematomas include vaginal or perineal laceration, episiotomy, or an operative delivery (Iskender, 2016). Any hematoma can also develop following stretch and rupture of a blood vessel without an associated laceration (Nelson, 2012). This may be especially true with forceps delivery. Occasionally, they are associated with an underlying coagulopathy (p. 782).


Obstentrics_Williams

Obstentrics_Williams. Perineal, vulvar, and paravaginal hematomas can develop rapidly and frequently cause excruciating pain (Fig. 41-12). A tense, tender swelling of varying size rapidly develops, encroaches on the vaginal lumen, and causes overlying skin or epithelium to become ecchymotic. A paravaginal hematoma may escape detection initially. However, symptoms of pelvic pressure, pain, or inability to void should prompt evaluation. Others may go undetected until other measures of hypovolemia become evident. When there is a supralevator extension, the hematoma extends upward in the paravaginal space and between the leaves of the broad ligament. The hematoma may escape detection until it can be felt on abdominal palpation or until hypovolemia develops. Imaging with sonography or computed tomographic scanning may be useful (Cichowski, 2017; Kawamura, 2014; Takeda, 2014).


Obstentrics_Williams

Obstentrics_Williams. Small hematomas often remained contained and show minimal expansion. In others, the tissues overlying an expanding hematoma may rupture from pressure necrosis. In some, profuse hemorrhage may follow, but in other cases, the hematoma drains in the form of large clots and old blood. In those that involve the paravaginal space and extend above the levator sling, retroperitoneal bleeding may be massive and occasionally fatal. Finally, we have encountered a few that rebled up to 2 weeks postpartum (Cunningham, 2017 a).


Obstentrics_Williams

Obstentrics_Williams. Vulvovaginal hematomas are managed according to their size, location, duration since delivery, and expansion. If bleeding ceases, then small-to moderate-sized hematomas may be treated expectantly until absorbed. But, if pain is severe or if the hematoma continues to enlarge, sutgical exploration is preferable. Blood loss with arge puerperal hematomas is neary always consideraby more than the clinical estimate. Hypovolemia is common, and transfusions are frequently required when surgical repair is necessary.


Obstentrics_Williams

Obstentrics_Williams. For repair, an incision is made at the point of maximal distention, blood and clots are evacuated, and bleeding points ligated. The cavity may then be obliterated with absorbable sutures. Often, no sites of bleeding are identified. Nonetheless, the evacuated hematoma cavity is surgically closed, and the vagina is packed for 12 to 24 hours. Supralevator hematomas are more diicult to treat. Although some can be evacuated by vulvar or vaginal incisions, laparotomy or interventional embolization, described next, is a consideration if bleeding continues. Angiographic embolization has become popular for management of some puerperal hematomas. This is especially true FIGURE 41 -7 Maternal death during home delivery caused by exsanguination from uterine inversion and a fundally implanted placenta accreta.


Obstentrics_Williams

Obstentrics_Williams. FIGURE 41 -7 Maternal death during home delivery caused by exsanguination from uterine inversion and a fundally implanted placenta accreta. will prompt closer examination of the birth canal. Although complete inversion is usually evident, the partially inverted uterus can be mistaken for a uterine myoma, and sonography can aid diferentiation (Pan, 2015; Smulian, 2013). Many cases are associated with immediate life-threatening hemorrhage, and a fourth require blood replacement (eoad, 2017). Once any degree of uterine inversion is recognized, several steps must be implemented urgently and simultaneously: 1. Immediate assistance is summoned, including obstetrical and anesthesia personnel. 2. Blood is brought to the delivery suite for potential use. 3. he woman is evaluated for emergency general anesthesia. Large-bore intravenous infusion systems are secured to begin rapid crystalloid infusion to treat hypovolemia while awaiting arrival of blood products. 4.


Obstentrics_Williams

Obstentrics_Williams. Large-bore intravenous infusion systems are secured to begin rapid crystalloid infusion to treat hypovolemia while awaiting arrival of blood products. 4. If the recently inverted uterus has not contracted and retracted completely and if the placenta has already separated, then the uterus may often be replaced simply by pushing up on the inverted fundus with the palm of the hand and ingers in the direction of the long axis of the vagina (Fig. 41-8). Some use two fingers rigidly extended to push the center of the fundus upward. Care is taken not to appy so much pressure as to peorate the uterus with the ingertips. 5.


Obstentrics_Williams

Obstentrics_Williams. 5. If the placenta is still attached, then attempts are made to reposition the uterus with the placenta in situ. Many recommend a trial of an intravenously administered tocolytic drug such as terbutaline, magnesium sulfate, or nitroglycerin for uterine relaxation and repositioning (You, 2006). If these fail to provide suicient relaxation, then a rapidly acting halogenated inhalational agent is administered. After the uterus is replaced, the placenta is carefully manually removed. 6. If uterine repositioning fails with the placenta attached, then it is peeled of and steady pressure with the fist, palm, or ingers is applied to the inverted fundus in an attempt to push it up into and through the dilated cervix as described in Step 4. FIGURE 41-8 Incomplete uterine inversion repositioned by using the abdominal hand for palpation of the crater-like depression while simultaneously gently pushing the inverted fundus upward.


Obstentrics_Williams

Obstentrics_Williams. FIGURE 41-8 Incomplete uterine inversion repositioned by using the abdominal hand for palpation of the crater-like depression while simultaneously gently pushing the inverted fundus upward. 7. Once the uterus is restored to its normal coniguration, tocolysis is stopped. Oxytocin is then infused, and other utero tonics may be given as described for atony (p. 759). Meanwhile, the operator maintains the fundus in its normal anatomical position while applying bimanual compression to control further hemorrhage until the uterus is well contracted (see Fig. 41-4). The operator continues to monitor the uterus transvaginally for evidence of subsequent inversion. A Bakri balloon has been used to maintain the repositioned uterus (Haeri, 2015; Ida, 2015).


Obstentrics_Williams

Obstentrics_Williams. In most cases, the inverted uterus can be restored to its normal position by the techniques just described. Occasionally, manual replacement fails. One cause is a dense m) ometrial constriction ring. At this point, laparotomy is imperative. The anatomical coniguration found at surgery can be confusing as shown in


Obstentrics_Williams

Obstentrics_Williams. Figure 41-9. With agents given for tocolysis, a combined efort is made to reposition the uterus by simultaneously pushing upward from below and pulling upward from above. Application of atraumatic clamps to each round ligament and upward traction may be helpul-the Huntinton procedure. In some cases, placing a deep traction suture in the inverted fundus or grasping it with tissue forceps may be of aid. Either or both of these may be technically diicult. If a constriction ring still prohibits repositioning, a sagittal surgical cut-Haultain incisionis made posteriorly through the muscular ring to release it. he exposed fundus can then be reinverted (Sangwan, 2009). After uterine replacement, tocolytics are stopped, oxytocin and other utero to nics are given, and the uterine incision is repaired. Risks of separation of this posterior hysterotomy incision during subsequent pregnancy, labor, and delivery are unknown. Further illustration and discussion is found in Cunningham and


Obstentrics_Williams

Obstentrics_Williams. Gilstrapis Operative Obstetrics, 3rd edition (Zahn, 2017). Clitoral crus Batholin gland , Bulbospongiosus m. A Colles fascia Ischioanal fossa hematoma c B Pudendal artery Vulvar hematoma branches Colles fascia cut edge Ischiocavenosus m. Dorsal atery of the clitoris Bulbospongiosus m. Perineal a. Superficial transvese perineal n. External anal sphinter n. Inferior rectal a. Levator ani m. --Gluteus maxinus m. FIGURE 41-11 Schematic drawing showing types of puerperal hematomas. A. Coronal view showing a supralevator hematoma. B. Coronal view showing an anterior perineal triangle hematoma. C. Perineal view showing posterior perineal triangle anatomy and an ischioanal fossa hematoma. (Reproduced with permission from Cunningham FG: Genital tract lacerations and hematomas. In Yeomans ER, Hofman BL, Gilstrap LC III, et al (eds): Cunningham and Gilstrap's Operative Obstetrics, 3rd edition. New York, McGraw-Hili Education, 201o7a.)


Obstentrics_Williams

Obstentrics_Williams. FIGURE 41-12 Let-sided anterior perineal triangle hematoma associated with a vaginal laceration following spontaneous delivery in a woman with consumptive coagulopathy from acute fatty liver of pregnancy. for supralevator or retroperitoneal hematomas. Embolization can be used primarily, or more likely secondarily, if surgical attempts at hemostasis have failed or if the hematoma is difficult to access surgically (Distefano, 2013; Lee, 2012; Poujade, 2012). he use of a Bakri balloon for a paracervical hematoma has also been described (Gizzo, 2013; Gronvall, 2013). Finally, ultrasound-guided drainage of a recurrent supralevator hematoma has been reported (Mukhopadhyay, 2015) .


Obstentrics_Williams

Obstentrics_Williams. Uterine rupture frequently is catastrophic. It may be primay, deined as occurring in a previously intact or unscarred uterus, or may be seconday and associated with a preexisting incision, injury, or anomaly of the myometrium. Some of the etiologies associated with uterine rupture are presented in Table 41-3. Importantly, the contribution of each of these underlying causes has changed remarkably during the past 50 years. Speciically, before 1960, when the cesarean delivery rate was much TABLE 41 -3. Some Causes of Uterine Rupture Surgery involving the myometrium: Myomectomy incision through or to the endometrium Deep cornual resection of interstitial fallopian tube Metroplasty Coincidental uterine trauma: Abortion with instrumentation-sharp or suction curette, sounds Sharp or blunt trauma-assaults, accidents, bullets, knives Congenital: Before delivery:


Obstentrics_Williams

Obstentrics_Williams. Coincidental uterine trauma: Abortion with instrumentation-sharp or suction curette, sounds Sharp or blunt trauma-assaults, accidents, bullets, knives Congenital: Before delivery: Persistent, intense, spontaneous contractions Labor stimulation-oxytocin or prostaglandins Intraamnionic instillation-saline or prostaglandins Perforation by internal uterine pressure catheter External trauma-sharp or blunt Uterine overdistention-hydramnios, multifetal pregnancy During delivery: Fetal anomaly distending lower segment Vigorous uterine pressure during delivery Difficult manual removal of placenta Acquired:


Obstentrics_Williams

Obstentrics_Williams. Fetal anomaly distending lower segment Vigorous uterine pressure during delivery Difficult manual removal of placenta Acquired: Sacculation of entrapped retroverted uterus lower and women of great parity were numerous, primary uterine rupture predominated. As the incidence of cesarean delivery rose and especially as a subsequent trial oflabor in these women became prevalent through the 1990s, uterine rupture through the cesarean hysterotomy scar became the preeminent cause (Gibbins, 2015; Mone, 2016). However, concurrent with the diminished enthusiasm for a trial of labor in women with a prior cesarean delivery, incidence trends for the two types of rupture have again changed. In a study of 3942 cases of uterine rupture in more than 15 million women, approximately half were in women with a prior cesarean delivery (Yao, 2017). In 40 cases of rupture at Parkland Hospital from 2009 to 2016, 15 events (37 percent) were primary, and 25 (63 percent) were secondary (Happe, 2017).


Obstentrics_Williams

Obstentrics_Williams. Additional risks for rupture include other previous operations or manipulations that traumatize the myometrium. Examples are uterine curettage or perforation, endometrial ablation, myomectomy, or operative hysteroscopy (Kieser, 2002; Pelosi, 1997). In a study by Porreco and colleagues (2009), seven of21 women without a prior cesarean delivery had undergone prior uterine surgery.


Obstentrics_Williams

Obstentrics_Williams. In developed countries, the incidence of rupture is 1 in 4800 deliveries (Getahun, 2012). During a 40-year period in Norway, the uterine rupture rate rose significantly to about 1 in 1560 deliveries (Al-Zirqi, 2016). he frequency of primary rupture, however, approximates 1 in 10,000 to 15,000 births (Porreco, 2009). As discussed, one reason is a decreased incidence of women of great parity. Another is that excessive or inappropriate uterine stimulation with oxytocin-previously a frequent cause-has mostly disappeared. Maggio and associates (2014) found no association between the number of Montevideo units and secondary uterine rupture. In addition, in a recent analysis of three trials comparing high-versus low-dose oxytocin regimens, the rate of uterine rupture did not difer between groups (Budden, 2014). The rate of rupture is elevated with sequential induction of labor with prostaglandins and oxytocin (Al-Zirqi, 2017). At Parkland Hospital, we too have encountered primary uterine


Obstentrics_Williams

Obstentrics_Williams. (Budden, 2014). The rate of rupture is elevated with sequential induction of labor with prostaglandins and oxytocin (Al-Zirqi, 2017). At Parkland Hospital, we too have encountered primary uterine rupture in a disparate number of women in whom labor was induced with prostaglandin E1•


Obstentrics_Williams

Obstentrics_Williams. Blunt abdominal trauma can precipitate uterine rupture. Although the distended pregnant uterus is surprisingly resistant, pregnant women sustaining such trauma should be watched carefully for signs of a ruptured uterus (Chap. 47, p. 927). In one study of 13 cases of primary uterine rupture, trauma accounted for three cases (Miller, 1996). Other causes of traumatic rupture that are uncommon today are those due to internal podalic version and extraction, diicult forceps delivery, breech extraction, and unusual fetal enlargement such as with hydrocephaly. Uncommon associations of rupture are uterine anomalies or multifetal pregnancy (Bankada, 2015; Tarney, 2013; Tola, 2014). Occasionally, focal inherent weakness in the myometrium predisposes to rupture. Examples include anatomical anomalies, leiomyomas, adenomyosis, choriocarcinoma, and connective-tissue defects such as Ehlers-Danlos syndrome (Arici, 2013; Nikolaou, 2013; Noh, 2013; Ramskill, 2014; Sun, 2016).


Obstentrics_Williams

Obstentrics_Williams. Rupture of the previously intact uterus during labor most often involves the thinned-out lower uterine segment. When the rent is in the immediate vicinity of the cervix, it frequently extends transversely or obliquely. When the rent forms in the portion of the uterus adjacent to the broad ligament, the tear FIGURE 41-13 Supracervical hysterectomy specimen showing uterine rupture during spontaneous labor with a vertical tear at the left lateral edge of lower uterine segment.


Obstentrics_Williams

Obstentrics_Williams. FIGURE 41-13 Supracervical hysterectomy specimen showing uterine rupture during spontaneous labor with a vertical tear at the left lateral edge of lower uterine segment. is usually longitudinal. Although these tears develop primarily in the lower uterine segment, they can extend upward into the active segment or downward through the cervix and into the vagina (Fig. 41-13). In some cases, the bladder may also be lacerated. If the rupture is of suicient size, the uterine contents will usually escape into the peritoneal cavity. If the presenting fetal part is firmly engaged, however, then only a portion of the fetus may be extruded from the uterus. Fetal prognosis is largely dependent on the degree of placental separation and magnitude ;f !ii�tei!�l he!ii;iih�be �!d hypovolemia. In some cases, the overlying peritoneum remains intact, and this usually is accompanied by hemorrhage that extends into the broad ligament to cause a large retroperitoneal hematoma.


Obstentrics_Williams

Obstentrics_Williams. Following vaginal delivery in an unscarred uterus, we and others have occasionally encountered cases of an incomplete tear on the inside of the uterus that extends vertically into the active segment and is a source of profuse hemorrhage (Conrad, 2015). These tears are usually not visible from below but are found at the time of hysterectomy for intractable bleeding despite a contracted uterus. Hemorrhage with this type of tear can be torrential, and bleeding is usually not slowed until the uterine artery pedicles are clamped bilaterally.


Obstentrics_Williams

Obstentrics_Williams. The varied clinical presentations of uterine rupture and its management are discussed in detail in Chapter 31 (p. 598). In the most recent maternal mortality statistics from the Centers for Disease Control and Prevention, uterine rupture accounted for almost 10 percent of deaths caused by hemorrhage (Creanga, 2015, 2017). Maternal morbidity includes hysterectomy that may be necessary to control hemorrhage. Rates of perinatal mortality and morbidity, which may include severe neurological impairment, are also high (Gibbins, 2015; Porreco, 2009). Maternal obesity comorbid with uterine rupture is associated with increased rates of adverse neonatal outcomes (Yao, 2017).


Obstentrics_Williams

Obstentrics_Williams. Maternal obesity comorbid with uterine rupture is associated with increased rates of adverse neonatal outcomes (Yao, 2017). Separation of the placenta-either partially or totally-from its implantation site before delivery is described by the Latin term abruptio placentae. Literally translated, this refers to "rending asunder of the placenta," which denotes a sudden accident that is a clinical characteristic of most cases. In the purest sense, the cumbersome-and thus seldom used-term premature separation of the normaly implanted placenta is most descriptive because it excludes separation of a placenta previa.


Obstentrics_Williams

Obstentrics_Williams. Placental abruption is initiated by hemorrhage into the decidua basalis. he decidua then splits, leaving a thin layer adhered to the myometrium. Consequently, the process begins as a decidual hematoma and expands to cause separation and compression of the adjacent placenta. Inciting causes of many cases have been posited. he phenomenon of impaired tropho blastic invasion with subsequent atherosis is related in some cases of preeclampsia complicated by abruption (Brosens, 2011). Inflammation or infection may be contributory (Mhatre, 2016; Nath, 2007). Histological findings cannot be used to determine timing of the abruption (Chen, 2017). Abruption likely begins with rupture of a decidual spi ral artery and then an expanding retroplacental hematoma.


Obstentrics_Williams

Obstentrics_Williams. Abruption likely begins with rupture of a decidual spi ral artery and then an expanding retroplacental hematoma. In the early stages of placental abruption, clinical symptoms may be absent. Even with continued bleeding and placen tal separation, placental abruption can still be either total or partial (Fig. 41-14). With either, bleeding typically insinuates itself between the membranes and uterus, ultimately escaping through the cervix to cause external hemorrhage. Less often, the blood is retained between the detached placenta and the uterus, leading to concealed hemorrhage and delayed diagnosis. The delay translates into greater maternal and fetal hazards. Also with concealed hemorrhage, the likelihood of consumptive coagulopathy is elevated. This is because increased pressure within the intervillous space, caused by the expanding retroplacental clot, forces more placental thromboplastin into the maternal circulation (p. 784).


Obstentrics_Williams

Obstentrics_Williams. Nfost blood in the retroplacental hematoma in a nontraumatic placental abruption is maternal. his is because hemorrhage derives from separation within the maternal decidua, and placental villi are usually initially intact. In 78 women at Parkland Hospital with a nontraumatic placental abruption, fetal-tomaternal hemorrhage was documented in only 20 percent-and all of these had < 10 mL fetal blood loss (Stettler, 1992). Atkinson and colleagues (2015) identiied fetal cells in peripheral blood in only 4 percent of 68 women with a placental abruption.


Obstentrics_Williams

Obstentrics_Williams. When clinically suspected, an abruption is seen on a freshly delivered placenta as a circumscribed depression on the maternal surface. hese usually measure a few centimeters in diameter and are covered by dark, clotted blood. Because several minutes are required for these anatomical changes to materialize, a very recently separated placenta may appear totally normal at delivery. Our experiences are like those of fetal complications such as nonreassuring fetal status, growth restriction, or death; or neonatal outcomes that include death, preterm delivery, or growth restriction.


Obstentrics_Williams

Obstentrics_Williams. External trauma-usually from motor vehicle accidents or aggravated assault-can cause placental separation. he frequency of abruption originating from trauma varies. Kettel (1988) and Staford (1988) and their associates have appropriately stressed that abruption can stem from relatively minor trauma. he clinical presentation and consequences of these abruptions difer somewhat from spontaneous cases. For example, associated fetomaternal hemorrhage, while seldom clinically signiicant with most spontaneous abruptions, is more common with trauma because of concomitant placental tears or "fractures" (Chap. 47, p. 928). Fetal abruption with concealed hemorrhage. To the right is a partial abruption with blood a third of women with a traumatic abrup and clots dissecting between membranes and decidua to the internal cervical os and tion reported by Pearlman (1990). In eight


Obstentrics_Williams

Obstentrics_Williams. FIGURE 41-14 Schematic of placental abruption. Shown to left is a total placental bleeding that averaged 12 mL was noted in then externally into the vagina. Benirschke and associates (2012) in that the "age" of the retroplacental clot cannot be determined exactly. In the example shown in Figure 41-15, a large dark clot is well formed, it has depressed the placental bulk, and it likely is at least several hours old. Deining severity of placental abruption is problematic. We have considered abruption severe when the fetus dies, however, maternal and fetal complications can be serious even with a liveborn fetus. Ananth and coworkers (2016) have deined severe abruption as displaying one or more of the following: (1) maternal sequelae that include disseminated intravascular coagulation, shock, transfusion, hysterectomy, renal failure, or death; women cared for at Parkland Hospital, we FIGURE 41-15 Partial placental abruption with a dark adherent clot.


Obstentrics_Williams

Obstentrics_Williams. FIGURE 41-15 Partial placental abruption with a dark adherent clot. found fetal-to-maternal hemorrhage of 80 to 100 mL in three of eight cases of traumatic placental abruption (Stettler, 1992). Importantly, in some cases of trauma, a nonreassuring fetal heart rate tracing may not be accompanied by other evidence of placental separation. A sinusoidal tracing is one example. Traumatic abruption is considered in more detail in Chapter 47 (p. 928).


Obstentrics_Williams

Obstentrics_Williams. Some cases of chronic placental separation begin early in pregnancy. Dugof and coworkers (2004) observed an association between some abnormally elevated maternal serum aneuploidy markers and subsequent abruption. Other have correlated irstand second-trimester bleeding with third-trimester placental abruption (Ananth, 2006; Weiss, 2004). In some cases of a chronic abruption, subsequent oligohydramnios developschronic abruption-oligohydramnios sequence-CAGS (Elliott, 1998). Even later in pregnancy, hemorrhage with retroplacental hematoma formation is occasionally arrested completely without delivery. hese women may have abnormally elevated serum levels of alpha-fetoprotein or placenta-specific RNAs as markers of the event (Miura, 2016; Ngai, 2012) .


Obstentrics_Williams

Obstentrics_Williams. he reported incidence of placental abruption varies because of diferent criteria used for diagnosis. hat said, its frequency averages 0.5 percent or 1 in 200 deliveries. From one database of almost 28 million births from 2006 through 2012, the incidence of placental abruption was nearly 1 percent (Ananth, 2016). From a cohort of more than 1.57 million births in the Netherlands, Ruiter and coworkers (2015) found the frequency was 0.22 percent-1 in 450. In more than 250,000 0.....) 5. FIGURE 41-16 Frequency of placental abruption and placenta previa by maternal age at Parkland Hospital from 2000 through 2015. deliveries at Parkland Hospital from 2000 through 2015, the incidence of placental abruption averaged 0.35 percent or 1 in 290 (Fig. 41-16).


Obstentrics_Williams

Obstentrics_Williams. deliveries at Parkland Hospital from 2000 through 2015, the incidence of placental abruption averaged 0.35 percent or 1 in 290 (Fig. 41-16). he frequency ofplacental abruption has risen in this country, and most ofthis increase is in blackwomen (Ananth, 2005, 2016). At Parkland Hospital, however, the frequency ofsevere abruption has declined. This discrepancy may be explained in part by the variations in management ofearly-onset preeclampsia (Chap. 40, p. 728). Specifically, with placental abruption so extensive as to kill theetus, the incidence was 0.24 percent or 1 in 420 births from 1956 through 1967 (Pritchard, 1967). As the number of high-parity women giving birth declined along with improved availability of prenatal care and emergency transportation, the frequency of abruption causing fetal death dropped to 0.12 percent through 1989 in our obstetrical population. And, most recently through 2015, it declined to 0.05 percent or 1 in 2060.


Obstentrics_Williams

Obstentrics_Williams. Overall, perinatal outcomes are influenced by gestational age, and the frequency of placental abruption rises across the third trimester. As seen in Figure 41-17, more than half of the placental abruptions at Parkland Hospital developed at gestational ages ::37 weeks. Perinatal mortality and morbidity, however, are more common with earlier abruptions (Furukawa, 2015a). Ofother related factors, major fetal congenital anomalies have greater association with placental abruption (Riihimaki, 20l3).


Obstentrics_Williams

Obstentrics_Williams. Although the rates of fetal death have declined, the contribution of abruption as a cause of stillbirth remains prominent because other causes have also decreased. For example, since the early 1990s, 10 to 12 percent of all third-trimester stillbirths at Parkland Hospital have been the consequence of placental abruption. Others have documented high perinatal mortality rates caused by placental abruption. Salihu and colleagues (2005) analyzed more than 15 million singleton births between 1995 and 1998. The perinatal mortality rate associated with placental abruption was 11r9 per 1000 births compared with 8 per 1000 for the general obstetrical population. 22.7 FIGURE 41-17 Frequency of placental abruption by gestational age at Parkland Hospital. Neonatal deaths are common following placental abruption.


Obstentrics_Williams

Obstentrics_Williams. 22.7 FIGURE 41-17 Frequency of placental abruption by gestational age at Parkland Hospital. Neonatal deaths are common following placental abruption. At Parkland Hospital, 15 percent ofliveborn neonates died. Perinatal morbidity-oten severe-is also common in surviving newborns (Abdella, 1984). Studies by Matsuda and coworkers (2003, 2013) reported that 20 percent of survivors developed cerebrl palsy. These observations are similar to ours from Parkland Hospital. Notably, 20 percent ofliveborn neonates ofwomen with an abruption had severe acidemia, deined by a cord arterial blood pH <7.0 or base deficit of::12 mmollL. One review conirmed the associated risk for cerebral palsy (Downes, 2017). Even so, nanth and coworkers (2017) attribute adverse neurodevelopmental outcomes to be largely attributable to preterm delivery.


Obstentrics_Williams

Obstentrics_Williams. Several predisposing factors raise the risk for placental abruption, and some are listed in Table 41-4.Advancing matenalage is one, although data are conlicting regarding women of reat pariy TABLE 41 -4. Risk Factors for Placental Abruption Increased age and parity 1.3-2.3 Preeclampsia 2.1-4.0 Chronic hypertension 1n.8-3.0 Chorioamnionitis 3.0 Preterm ruptured membranes 2.4-4.9 Low birthweight 14.0 Cigarette smoking 1.4-1.9 Single umbilical artery 3.4 NA = not available. Data from Ananth/ 1999a/b/ 2004/ 2007; Aviram/ 2015; Gutvirtz/ 2016; Morgan/ 2016; Nath/ 2007/ 2008; Ruiter/ 2015.


Obstentrics_Williams

Obstentrics_Williams. Cigarette smoking 1.4-1.9 Single umbilical artery 3.4 NA = not available. Data from Ananth/ 1999a/b/ 2004/ 2007; Aviram/ 2015; Gutvirtz/ 2016; Morgan/ 2016; Nath/ 2007/ 2008; Ruiter/ 2015. (Okby, 2017; Pritchard, 1991). ace or ethnicity also appears to be important. In almost 366,000 deliveries at Parkland Hospital, abruption severe enough to kill the fetus was most common in black and white women-1 in 200, less so in Asian women-1 in 300, and least common in Latin-American women-1 in 350 (Pritchard, 1991). Aomilial association was found in an analysis of a Norwegian population-based registry (Rasmussen, 2009). If a woman had a severe abruption, the risk for her sister was doubled.


Obstentrics_Williams

Obstentrics_Williams. Some form of hypertension is the most frequent condition associated with placental abruption. his includes gestational hypertension, preeclampsia, chronic hypertension, or a combination thereof. In a report by Pritchard and colleagues (1991) that described 408 women with placental abruption and fetal demise, hypertension was apparent in half once hypovolemia was corrected. Half of these latter women-a fourth of all 408-had chronic hypertension. Looked at another way, one Maternal-Fetal Medicine Units (MFMU) Network study found that 1.5 percent of pregnant women with chronic hypertension sufered placental abruption (Sibai, 1998). As discussed in Chapter 50 (p. 978), at Parkland Hospital, the frequency of placental abruption in treated chronically hypertensive women was almost 1 percent, which was threefold higher than the 0.3-percent baseline C..10rgan, 2016).


Obstentrics_Williams

Obstentrics_Williams. Chronic hypertension with superimposed preeclampsia or with fetal-growth restriction confers an even greater risk (Ananth, 2007). Even so, the severity of hypertension does not necessarily correlate with abruption incidence (Morgan, 2016; Zetterstrom, 2005). The long-term efects of these associations are apparent from the signiicantly elevated cardiovascular mortality risk in women with prior abruption, with or without chronic hypertension (DeRoo, 2016; Pariente, 2013). Observations from the Magpie Trial Collaborative Group suggest that women with preeclampsia, with or without chronic hypertension, given magnesium sulfate may have a reduced risk for abruption (Altman, 2002).


Obstentrics_Williams

Obstentrics_Williams. he abruption risk substantially rises when placental membranes rupture before term (American College of Obstetricians and Gynecologists, 2016a; Hackney, 2016). Major and colleagues (1995) reported that 5 percent of 756 women with ruptured membranes between 20 and 36 weeks' gestation developed an abruption. It was 17 percent with previable prematurely ruptured membranes (Kibel, 2016). he risk for abruption with preterm rupture is further increased with comorbid infection (Ananth, 2004). In these cases, inlammation and infection as well as preterm delivery may be primary causes leading to abruption (Nath, 2007, 2008). Somewhat related, Aviram and coworkers (2015) found an eightfold higher abruption risk in pregnancies �34 weeks if hydramnios was comorbid. Abrupt uterine decompression during membrane rupture may be an inciting factor.


Obstentrics_Williams

Obstentrics_Williams. Many of the predisposing factors are chronic, and in these cases, placental abruption has a high recurrence rate. Pritchard and associates (1970) identiied a recurrence rate of 12 percentand half of these caused another fetal death. Furuhashi and colleagues (2002) reported a 22-percent recurrence rate-half recurred at a gestational age 1 to 3 weeks earlier than the first abruption. In the Dutch study mentioned previously, Ruiter and coworkers (2015) cited a recurrence risk of 5.8 percent. Looked at a second way, Tikkanen and associates (2006) found that of 114 parous women who experienced an abruption, 9 percent had a prior abruption. A third perspective is provided by a population-based study of 767,000 pregnancies reported by Rasmussen and Irgens (2009). They found a 6.5-fold higher risk for recurrence of a "mild" abruption and 11.5-fold risk for a "severe" abruption. For women who had two severe abruptions, the risk for a third was increased 50-fold.


Obstentrics_Williams

Obstentrics_Williams. Management of a pregnancy subsequent to an abruption is diicult because another separation may suddenly occur, even remote from term. In many of these recurrences, fetal wellbeing is almost always reassuring beforehand. hus, antepartum fetal testing is usually not predictive. Because term abruptions tend to be recurrent, Ruiter and coworkers (2015) recommend labor induction at 37 weeks. Our practice at Parkland Hospital is to induce labor at 38 weeks if other complications do not develop beforehand. Cigarette smoking is linked to an elevated risk for abruption (vIisra, 1999; Naeye, 1980). Results of a metaanalysis of 1.6 million pregnancies included a twofold risk for abruption in smokers (Ananth, 1999b). This risk was five-to eightfold if smokers had chronic hypertension, severe preeclampsia, or both. Similar findings are reported by others (Hogberg, 2007; Kaminsky, 2007). Antepartum Vitamin C and E were reported to be protective for abruption in smokers (Abramovici, 2015).


Obstentrics_Williams

Obstentrics_Williams. Cocaine abuse is linked with an alarming frequency of placental abruption (Addis, 2001; Cressman, 2014). Bingol and colleagues (1987) described 50 women who abused cocaine during pregnancy-eight had a stillbirth caused by placental abruption. Uterine leiomyomas, especially if located near the mucosal surface behind the placental implantation site, can predispose to placental abruption. This was reviewed recently by Ezzedine and Norwitz (2016). Isolated single umbiical artey is associated with a 3.4-fold increased risk for placental abruption (Gutvirtz, 2016). Twins resulting from infertility treatments also carry greater risk (Okby, 2017). Subclinical hypothyroidism or high levels of antithyroid antibodies have been associated with a two-to threefold higher risk for abruption (Abbassi-Ghanavati, 2010; Casey, 2014; Maraka, 2016).


Obstentrics_Williams

Obstentrics_Williams. Women afected by some of the thrombophilias have higher associated rates of thromboembolic disorders during pregnancy. However, the link with placental abruption is less clear (American College of Obstetricians and Gynecologists, 2017 a,b). Lupus anticoagulant is associated with maternal floor infarction of the placenta but is less so with typical abruptions. No convincing evidence supports a role for thrombophilias and placental abruption. Most women with a placental abruption have sudden-onset abdominal pain, vaginal bleeding, and uterine tenderness. In a prospective study, Hurd and colleagues (1983) reported that 78 percent with placental abruption had vaginal bleeding, 66 percent had uterine tenderness or back pain, and 60 percent had a nonreassuring fetal status. Other indings included fre quent contractions and persistent hypertonus. In a ifth of these women, preterm labor was diagnosed, and abruption was not suspected until fetal distress or death followed.


Obstentrics_Williams

Obstentrics_Williams. Importantly, the signs and symptoms of placental abruption can vary considerably. In some women, external bleeding can be profuse, yet placental separation may not be so extensive as to compromise the fetus. In others, there may be no external bleeding, but the placenta is suiciently sheared of that the fetus is dead-a concealed abruption. In one unusual case, a multiparous woman cared for at Parkland Hospital presented with a nosebleed. She had no abdominal or uterine pain, tenderness, or vaginal bleeding. Her fetus was dead, however, and her blood did not clot. he plasma ibrinogen level was 25 mg/dL. Labor was induced, and a total abruption was conirmed at delivery.


Obstentrics_Williams

Obstentrics_Williams. With severe placental abruption, the diagnosis generally is obvious. From the previous discussion, it follows that less severe, more common forms of abruption cannot always be recognized with certainty. hus, the diagnosis is one of exclusion. Unfortunately, no laboratory tests or other diagnostic methods accurately conirm lesser degrees of placental separation. Sonography has limited use because the placenta and fresh clots may have similar imaging characteristics. Glantz and Purnell (2002) reported only 24-percent sensitivity for sonography in 149 consecutive women with a suspected placental abruption. Important, negative indings with sonographic examination do not exclude placental abruption. Conversely, magnetic resonance (MR) imaging is highly sensitive for placental abruption and should be considered if the diagnostic information would change management (Masselli, 2011).


Obstentrics_Williams

Obstentrics_Williams. With abruption, some degree of intravascular coagulation is almost universal. hus, elevated serum levels of D-dimers may be suggestive, but this has not been adequately tested. Preliminary data show that serum alpha-fetoprotein levels > 280 �g/L have a positive-predictive value of 97 percent (Ngai, 2012).


Obstentrics_Williams

Obstentrics_Williams. hus, in the woman with vaginal bleeding and a live fetus, it is often necessary to exclude placenta previa and other causes of bleeding by clinical and sonographic evaluation. It has long been taught-perhaps with some justiication-that painful uterine bleeding signiies placental abruption, whereas painless uterine bleeding is indicative of placenta previa. he diferential diagnosis is usually not this straightforward, and labor accompanying previa may cause pain suggestive of placental abruption. On the other hand, pain from abruption may mimic normal labor, or it may be painless, especially with a posterior placenta. At times, the cause of the vaginal bleeding remains obscure even after delivery.


Obstentrics_Williams

Obstentrics_Williams. Placental abruption is one of several notable obstetrical entities that may be complicated by massive and sometimes torrential hemorrhage. Hypovolemic shock is caused by maternal blood loss. In an earlier report from Parkland Hospital, Pritchard and Brekken (1967) described 141 women with abruption so severe as to kill the fetus. Blood loss in these women often amounted to at least half of their pregnant blood volume. Importantly, massive blood loss and shock can develop with a concealed abruption. Prompt treatment of hypotension with crystalloid and blood infusion is essential, and resuscitation steps are described later (p. 788). onic fluid embolism-led to the initial recognition of di brination syndrome. his syndrome is currently referred to as lation, which later is described more broadly on page 782.


Obstentrics_Williams

Obstentrics_Williams. onic fluid embolism-led to the initial recognition of di brination syndrome. his syndrome is currently referred to as lation, which later is described more broadly on page 782. is intravascular activation of clotting. Abruption is the most common cause of clinically profound consumptive coagulop athy in obstetrics-and indeed, probably in all of medicine (Cunningham, 2015).


Obstentrics_Williams

Obstentrics_Williams. An important consequence of intravascular coagulation is the activation of plasminogen to plasmin, which lyses ibrin microemboli to maintain microcirculatory patency. With placental abruption severe enough to kill the fetus, there are always pathological levels of ibrinogen-ibrin degradation products and D-dimers in maternal serum (Erez, 2015). heir quantiication is not clinically useful. In a third of women with an abruption severe enough to kill the fetus, the plasma ibrinogen level will be < 150 mg/ dL. hese levels are dependent on the maternal preabruption ibrinogen level, and thus higher levels are "protective" (Cunningham, 2015; Wang, 2016). Clinically signiicant low levels may cause troublesome surgical bleeding. Levels of several other coagulation factors are also variably decreased. In addition, thrombocytopenia, sometimes profound, may accompany severe hypoibrinogenemia initially and becomes common after repeated blood transfusions.


Obstentrics_Williams

Obstentrics_Williams. Consumptive coagulopathy is more likely with a concealed abruption because intrauterine pressure is higher. his forces more thromboplastin into the large veins draining the implantation site. With a partial abruption and a live fetus, severe coagulation defects are less common. Our experience has been that if serious coagulopathy develops, it is usually evident by the time abruption symptoms appear. At the time of cesarean delivery, it is not uncommon to ind widespread extravasation of blood into the uterine musculature and beneath the serosa (Fig. 41-18). It is named after Couvelaire, who in the early 1900s termed it uteroplacental apoplexy. hese myometrial hemorrhages seldom cause uterine atony, and alone they are not an indication for hysterectomy. Efusions of blood are also seen beneath the tubal serosa, between the leaves of the broad ligaments, in the substance of the ovaries, and free in the peritoneal cavity.


Obstentrics_Williams

Obstentrics_Williams. FIGURE 41-18 Couvelaire uterus from total placental abruption ater cesarean delivery. Blood markedly infiltrates the myometrium to reach the serosa, especially at the cornua. The small serosaloleio myoma seen on the lower anterior uterine surface is an incidental finding. (Used with permission from Dr. Angela Fields Walker.)


Obstentrics_Williams

Obstentrics_Williams. Acute kidney injury AI) is a general term describing renal dysfunction from many causes (Chap. 53, p. 1036). Delayed or incomplete treatment of hypovolemia with severe placental abruption can be one. However, even with abruption complicated by severe disseminated intravascular coagulation, prompt and vigorous treatment of hemorrhage with blood and crystalloid solution usually prevents clinically signiicant renal dysfunction. The risk for renal injury with abruption is magnified when preeclampsia coexists (Alexander, 2015; Drakeley, 2002). Most cases of AKI are reversible and not so severe as to require dialysis. Generally, long-term outcomes are good (Arazi, 2015). That said, irreversible acute cortical necrosis encountered in pregnancy can be associated with abruption (Gopalakrishnan, 2015).


Obstentrics_Williams

Obstentrics_Williams. Rarely, pituitary failure-Sheehan syndrome-follows severe intrapartum or early postpartum hemorrhage. Described in Chapter 58 (1133), the exact pathogenesis is not well understood, especially because endocrine abnormalities are infrequent even in women who sufer catastrophic hemorrhage (Matsuwaki, 2014; Robalo, 2012).


Obstentrics_Williams

Obstentrics_Williams. Treatment of the woman with a placental abruption varies depending on her clinical condition, gestational age, and the amount of associated hemorrhage. With a living viable-aged fetus, and with vaginal delivery not imminent, emergency cesarean delivery is chosen by most. In some women, fetal compromise will be evident as shown in Figure 41-19. When evaluating fetal status, sonographic conirmation of fetal heart activity may be necessary because sometimes an electrode applied directly to a dead fetus will provide misleading information by recording the maternal heart rate. If the fetus has died or if it is not considered suiciently mature to live outside the uterus, then FIGURE 41-19 Placental abruption with fetal compromise. Lower panel: Uterine hypertonus with a baseline pressure of 20 to 25 mm Hg and frequent contractions peaking at approximately 75 mm Hg. Upper panel: The fetal heart rate demonstrates baseline bradycardia with repetitive late decelerations.


Obstentrics_Williams

Obstentrics_Williams. vaginal delivery is preferable. In either case, prompt and intensive resuscitation with blood plus crystalloid is begun to replace blood lost from retroplacental and external hemorrhage. hese measures are lifesaving for the mother and hopefully for her fetus. If the diagnosis of abruption is uncertain and the fetus is alive and without evidence of compromise, then close observation may be warranted provided that immediate intervention is available. Colon and coworkers (2016) performed a randomized trial and found no beneits to magnesium sulfate tocolysis given to women with a preterm "nonsevere" abruption at 24 to 34 weeks' gestation.


Obstentrics_Williams

Obstentrics_Williams. The compromised fetus is usually best served by cesarean delivery, and the speed of response is an important factor in perinatal outcomes. Kayani and coworkers (2003) studied this relationship in 33 singleton pregnancies with a clinically overt placental abruption and fetal bradycardia. Of the 22 neurologically intact survivors, 15 were delivered within a 20-minute decision-to-delivery interval. However, eight of 11 infants who died or developed cerebral palsy were delivered with intervals > 20 minutes. A major hazard to cesarean delivery is imposed by clinically signiicant consumptive coagulopathy. Preparations include plans for blood and component replacement and assessment of coagulation-especially fibrinogen levels.


Obstentrics_Williams

Obstentrics_Williams. If the fetus has died, then vaginal delivery is usually preferred. As reviewed earlier, hemostasis at the placental implantation site depends primarily on myometrial contraction and not blood coagulability. Thus, after vaginal delivery, uterotonic agents and uterine massage are used to stimulate myometrial contractions. Uterine muscle ibers compress placental site vessels and prompt hemostasis even if coagulation is defective. In some instances, vaginal delivery may not be preferable, even with a dead fetus. One example is brisk hemorrhage that cannot be successfully managed by vigorous blood replacement. Others are the myriad obstetrical complications that prohibit vaginal delivery in general. hese are listed in Table 30-1 (p. 568).


Obstentrics_Williams

Obstentrics_Williams. In some women with extensive placental abruption, labor tends to be rapid because the uterus is usually persistently hypertonic. This can magniy fetal compromise. In some cases, baseline intraamnionic pressures reach 50 mm Hg or higher, and with contractions, pressures may attain levels exceeding 100 mm Hg. Overall, however, irst-and second-stage labor do not appear to be shortened (Downes, 2016).


Obstentrics_Williams

Obstentrics_Williams. Early amniotomy has long been championed in the manage ment of placental abruption. his ostensibly achieves better spi ral artery compression to diminish implantation site bleeding and reduce thromboplastin infusion into the maternal vascular system. Although evidence supporting this theY is lacking, membrane ruprure may hasten delivery. However, if the fetus is small, the intact sac may be more eicient in promoting cervical dilation. If rhythmic uterine contractions are not superimposed on baseline hypertonus, then oxytocin is given in standard doses. No data indicate that oxytocin augments thromboplas tin escape into the maternal circulation to worsen coagulopathy (Clark, 1995; Pritchard, 1967). In light of hypertonus associ ated with abruption, misoprostol may be a less favored induc tion agent due to its association with uterine tachysystole.


Obstentrics_Williams

Obstentrics_Williams. In the past, some had set arbitrary time limits to permit vaginal delivery. Instead, experiences illustrate that maternal outcome depends on the diligence with which adequate luid and blood replacement therapy are pursued rather than on the interval to delivery. Observations from Parkland Hospital described by Pritchard and Brekken (1967) are similar to those from the University of Virginia reported by Brame and associates (1968). Specifically, women with severe abruption who were transfused during 18 hours or more before delivery had similar outcomes to those in whom delivery was accomplished sooner. Expectant Management with a Preterm Fetus


Obstentrics_Williams

Obstentrics_Williams. Expectant Management with a Preterm Fetus If possible, delaying delivery may benefit an immature fetus. Bond and colleagues (1989) expectantly managed 43 women with placental abruption before 35 weeks' gestation, and 31 of them were given tocolytic therapy. he mean interval-todelivery for all 43 was approximately 12 days. Cesarean delivery was performed in 75 percent, and there were no stillbirths. As discussed earlier, women with a very early abruption may develop chronic abruption-oligohydramnios sequence. In one report, Elliott and coworkers (1998) described four women with an abruption at a mean gestational age of 20 weeks who developed oligohydramnios and delivered at an average gestational age of 28 weeks. In a description of 256 women with an abruption at <28 weeks' gestation, Sabourin and colleagues (2012) reported that a mean of 1.6 weeks was gained. Of the group, 65 percent were delivered <29 weeks, and half of all women underwent emergent cesarean delivery.


Obstentrics_Williams

Obstentrics_Williams. Unfortunately, even continuous fetal heart rate monitoring does not guarantee universally good outcomes. For example, a normal tracing may precede sudden further separation with instant fetal compromise. In some of these, if the separation is suicient, the fetus will die before it can be delivered. Tocolysis is advocated by some for suspected abruption if the fetus does not display compromise. Some investigators have observed that tocolysis improved outcomes in a highly selected cohort of women with preterm pregnancies (Bond, 1989; Combs, 1992; Sholl, 1987). In another study, Towers and coworkers (1999) administered magnesium sulfate, terbutaline, or both to 95 of 131 women with abruption diagnosed before 36 weeks. The perinatal mortality rate was 5 percent in both groups with or without tocolysis. Similar results were reported from a randomized trial (Colon, 2016). We are of the opinion that suspected placental abruption contraindicates use of tocolytic agents.


Obstentrics_Williams

Obstentrics_Williams. The Latin previa means going bore-and in this sense, the placenta goes before the fetus into the birth canal. In obstetrics, placenta previa describes a placenta that is implanted somewhere in the lower uterine segment, either over or very near the internal cervical os. Because these anatomical relationships cannot always be precisely deined, and because they frequently change across pregnancy, terminology can sometimes be confusing. Beginning with the use of sonography in obstetrics, the term placental migration was coined to describe the apparent movement of the placenta away from the internal os (King, 1973). Obviously, the placenta does not move per se, and the mechanism of apparent movement is not completely understood. To begin with, migration is clearly a misnomer, because decidual invasion anchors chorionic villi at the cervical os. Explanations of placental migration are likely additive.


Obstentrics_Williams

Obstentrics_Williams. Explanations of placental migration are likely additive. First, apparent movement of the low-lying placenta relative to the internal os is related to the imprecision of two-dimensional sonography. Second, as pregnancy progresses, growth of the lower and upper uterine segments difers. With greater blood low in the upper uterus, placental growth is more likely directed toward the fundus-trophotropism. Many of those placentas that "migrate" most likely never were circumferentially implanted with true villous invasion that reached the internal cervical os. Importanty, a low-ying placenta or placenta previa is less likey to "migrate JJ if there is a prior cesarean delivey scar.


Obstentrics_Williams

Obstentrics_Williams. he frequency of placental migration has been quantiied. Sanderson and Milton (1991) studied 4300 women at midpregnancy and found that 12 percent had a low-lying placenta. Of placentas not covering the internal os, previa did not persist, and none subsequently had placental hemorrhage. Conversely, approximately 40 percent of placentas that covered the os at midpregnancy continued to do so until delivery. Thus, placentas that lie close to but not over the internal os up to the early third trimester are unlikely to persist as a previa by term (Heller, 2014; Parrott, 2015). However, other evidence from Bohrer and associates (2012) showed that a second-trimester low-lying placenta was associated with antepartum admission for hemorrhage and increased blood loss at delivery.


Obstentrics_Williams

Obstentrics_Williams. The likelihood that placenta previa persists after being identiied sonographically at given epochs before 28 weeks' gestation is shown in Figure 41-20. For twin pregnancies, similar findings are reported until 23 weeks, after which the previa persistence rate is much higher (Kohari, 2012). Staford and coworkers FIGURE 41 -21 Placenta previa showing that copious hemorrhage could be anticipated with any cervical dilatation. • Previa, prior CD ) • Previa, no prior CD � • 1-5 mm,prior CD )S 75 • 1-5 mm,no prior CD


Obstentrics_Williams

Obstentrics_Williams. • Previa, prior CD ) • Previa, no prior CD � • 1-5 mm,prior CD )S 75 • 1-5 mm,no prior CD FIGURE 41-20 Likelihood of persistence of placenta previa or low-lying placenta 1 to 5 mm from the internal os at delivery. These are shown as a function of sonographic diagnosis at three pregnancy epochs. CD = cesarean delivery. (Data from Oyelese, 2006.) (2010), but not Trudell and colleagues (2013), found that a previa and a third-trimester cervical length <30 mm elevated the risks for hemorrhage, uterine activity, and preterm birth. Friszer and associates (2013) showed that women admitted for bleeding had a greater chance of delivery in the subsequent 7 days when the cervical length was <25 mm, although Trudell (2013) again did not confirm this.


Obstentrics_Williams

Obstentrics_Williams. Terminology for placenta previa has evolved, and from a Fetal Imaging Workshop sponsored by the National Institutes of Health (NIH), the following classiication was recommended: • Placenta previa-the internal os is covered partially or completely by placenta (Figs. 41-21 and 41-22). In the past, these were further classiied as either total or partial previa. FIGURE 41-22 On speculum examination, placenta is visible protruding through the cervical os. (Used with permission from Dr. Maureen E. Flowers.) • Low-ying placenta-implantation in the lower uterine segment is such that the placental edge does not cover the internal os but lies within a 2-cm wide perimeter around the os. A previously used term, marginal previa, described a placenta that was at the edge of the internal os but did not overlie it (Reddy, 2014).


Obstentrics_Williams

Obstentrics_Williams. Clearly, the classification of some cases of previa will depend on cervical dilation at the time of assessment (Dashe, 2013; Reddy, 2014). For example, a low-lying placenta at 2-cm dilation may become a partial placenta previa at 4-cm dilation because the cervix has opened to expose the placental edge. Conversely, a placenta previa that appears to be total before cervical dilation may become partial at 4-cm dilation because the cervical opening now extends beyond the edge of the placenta. Digital papation in an attempt to ascertain these changing relations between the placental edge and intenal os as the cervix dilates usualy causes severe hemorrhage! With any degree of placenta previa, a certain amount of spontaneous placental separation is inevitable during lower uterine segment remodeling and cervical dilation. Although this frequently causes bleeding, and thus technically constitutes a placental abruption, this term is usually not applied in these instances.


Obstentrics_Williams

Obstentrics_Williams. Somewhat but not always related is vasa previa, in which fetal vessels course through membranes and present at the cervical os (Catanzarite, 2016). Vasa previa was recently reviewed by the Society for Maternal-Fetal Medicine (2015) and is discussed in Chapter 6 (p. 118). he incidence of placenta previa has risen during past 30 years. Reported incidences average 0.3 percent or 1 case per 300 to 400 deliveries. he frequency at Parkland Hospital from 1988 through 2003 for nearly 250,000 births was 2.6 per 1000. For the 2004 to 2015 epoch, it rose to 3.8 per 1000. Similar frequencies have been reported from Austria, Finland, and Israel (Kollmann, 2016; Raisanen, 2014; Rosenberg, 2011). Several demographic factors may contribute to this higher risk for placenta previa. First, maternal age raises the frequency of placenta previa (Biro, 2012; Roberts, 2012). In the First-and


Obstentrics_Williams

Obstentrics_Williams. Several demographic factors may contribute to this higher risk for placenta previa. First, maternal age raises the frequency of placenta previa (Biro, 2012; Roberts, 2012). In the First-and Second-Trimester E val uation of Risk (FASTER) trial, which included more than 36,000 women, the frequency of previa was 0.5 percent for women <35 years compared with 1.1 percent in those :35 years (Cleary-Goldman, 2005). At Parkland Hospital, this incidence difered from a low rate of approximately 0.65 per 1000 births for women ; 19 years to almost 10 per 1000 births for women older than 35 (see Fig. 41-16). Multpariy also elevates the risk for previa (Raisanen, 2014). Obviously, the efects of advancing maternal age and parity are confounding. Still, Babinszki and colleagues (1999) reported that the 2.2-percent incidence in women with parity of five or greater was significantly higher than that of women with lower parity. he interpregnancy interval does not afect this rate (Fox, 2015).


Obstentrics_Williams

Obstentrics_Williams. he interpregnancy interval does not afect this rate (Fox, 2015). Cigarette smoking increases the relative risk of placenta previa at least twofold (Usta, 2005). It has been postulated that carbon monoxide hypoxemia causes compensatory placental hypertrophy and more surface area. Smoking may also be related to decidual vasculopathy. Last, uterine leiomyomas are a risk factor for previa Oenabi, 2017).


Obstentrics_Williams

Obstentrics_Williams. Several clinical characteristics also raise previa risks. Foremost, women with one or more prior cesarean deliveries are at greater risk for subsequent placental disorders that include placenta previa, abruption, or morbidly adherent placenta (Gibbins, 2018; Klar, 2014). The cumulative risks for placenta previa that accrue with the increasing number of cesarean deliveries are extraordinary. The risk rises even further if there was a prior prelabor cesarean delivery (Downes, 2015). In one MFMU Network study of 30,132 women undergoing cesarean delivery, the incidence was 1.3 percent for those with only one prior cesarean delivery, but it was 3.4 percent if there were six or more prior cesareans (Silver, 2006). In a retrospective cohort of nearly 400,000 women who were delivered of two consecutive singletons, those with a cesarean delivery for the first pregnancy had a 1.6-fold greater risk for previa in the second pregnancy (Gurol-Urganci, 2011). hese same investigators reported a


Obstentrics_Williams

Obstentrics_Williams. consecutive singletons, those with a cesarean delivery for the first pregnancy had a 1.6-fold greater risk for previa in the second pregnancy (Gurol-Urganci, 2011). hese same investigators reported a 1.5-fold higher risk from six similar population-based cohort studies. The likelihood of previa is increased more than eightfold in women with parity greater than four and who have more than four prior cesarean deliveries (Gesteland, 2004; Gilliam, 2002).


Obstentrics_Williams

Obstentrics_Williams. Importantly, women with a prior uterine incision and placenta previa have an elevated likelihood that cesarean hysterectomy will be necessary because of an associated morbidly adherent placenta (Wei, 2014). In one study, 6 percent of women with a primary cesarean delivery for previa required a hysterectomy. his rate was 25 percent for women with a previa undergoing repeat cesarean delivery (Frederiksen, 1999). Maternal serum aphaetoprotein (MSAFP) levels, if abnormally elevated for otherwise unexplained reasons during prenatal screening, raise the risk for previa and a host of other abnormalities. Moreover, women with a previa and comorbid MSAFP level :2.0 multiples of the median (MoM) at 16 weeks' preterm birth (Chap. 14, p. 283).


Obstentrics_Williams

Obstentrics_Williams. Last, assisted reproductive technoloy AR) used for concep tion elevates previa risks. Some of this association may derive from overlapping efects. For example, older women comprise a signiicant portion of ART patients (Luke, 2017). In addition, multifetal gestation is a well-known risk of both in vitro fertil ization and previa. However, even adjusting for these overlap ping elements, ART is still associated with higher previa rates (Romundstad, 2006).


Obstentrics_Williams

Obstentrics_Williams. Painless bleeding is the most characteristic event with placenta previa. Bleeding usually does not develop until near the end of the second trimester or later, but it can begin even before mid pregnancy. And undoubtedly, some late abortions are caused by an abnormally located placenta. Bleeding from a previa usu in a woman who has had an uneventful prenatal course. his so-called sentinel bleed is rarely so profuse as to prove fatal. Usu ally it ceases, only to recur. However, in perhaps 10 percent of women, particularly those with a placenta implanted near but not over the cervical os, there is no bleeding until labor onset. Bleeding at this time varies from slight to profuse, and it may clinically mimic placental abruption.


Obstentrics_Williams

Obstentrics_Williams. Bleeding at this time varies from slight to profuse, and it may clinically mimic placental abruption. A speciic sequence of events leads to bleeding in cases in which the placenta is located over the internal os. First, the uterine body remodels to form the lower uterine segment. With this, the internal os dilates, and some of the implanted placenta inevitably separates. Bleeding that ensues is augmented by the inherent inability of myometrial fibers in the lower uterine segment to contract and thereby constrict torn vessels. Similarly, bleeding from this lower segment implantation site also frequently continues ater placentl delivery. Last, there may be lacerations in the friable cervix and lower segment. These may be especially problematic following manual removal of a somewhat adhered placenta.


Obstentrics_Williams

Obstentrics_Williams. Morbidy adherent placentas are a frequent and serious complication associated with placenta previa. Described later (p. 777), this abnormally firm placental attachment derives in part from poorly developed decidua that lines the lower uterine segment. Biswas and coworkers (1999) performed placental bed biopsies in 50 women with a previa and in 50 control women. Trophoblastic giant-cell iniltration of spiral arterioles-rather than endovascular trophoblast cells-was found in half of previa specimens. In contrast, only 20 percent of biopsies from normally implanted placentas had these changes. In another study of 514 cases of previa, abnormal placental attachment was identiied in 7 percent (Frederiksen, 1999). As discussed, previa overlying a prior cesarean incision conveys a particularly high risk for morbidly adherent placenta.


Obstentrics_Williams

Obstentrics_Williams. Coagulation dects are rare complications of placenta previa, even when implantation site separation is extensive (Cunningham, 2015). Placental thromboplastin, which incites the intravascular coagulation seen with placental abruption, is presumed to readily escape through the cervical canal rather than be forced into the maternal circulation. he paucity of large myometrial veins in this area may also be protective.


Obstentrics_Williams

Obstentrics_Williams. Whenever there is uterine bleeding after midpregnancy, placenta previa or abruption are always considered. In the Canadian Perinatal Network study discussed earlier (p. 758), placenta previa accounted for 21 percent of women admitted from 22 to 28 weeks' gestation with vaginal bleeding (Sabourin, 2012). Previa should not be excluded until sonographic evaluation has clearly proved its absence. If sonography is not readily available, diagnosis by clinical examination is done using the double set-up technique because it requires that a inger be passed through the cervix and the placenta palpated. A digital examination should not be performed unless delivery is planned. A cervical digital examination is done with the woman in an operating room and with preparations or immediate cesarean delivey. Even the gentlest examination can cause torrential hemorrhage. Fortunately, double set-up examination is rarely necessary because placental location can almost always be ascertained


Obstentrics_Williams

Obstentrics_Williams. cesarean delivey. Even the gentlest examination can cause torrential hemorrhage. Fortunately, double set-up examination is rarely necessary because placental location can almost always be ascertained sonographically.


Obstentrics_Williams

Obstentrics_Williams. Quick and accurate localization can be accomplished using standard sonographic techniques (American Institute of Ultrasound in Medicine, 2013). his is usually done with transabdominal sonography. If the placenta clearly overlies the cervix or if it lies away from the lower uterine segment, the examination has excellent sensitivity and negative-predictive value (Olive, 2006; Quant, 2014). Obese women may have limitations of visualization of the lower uterine segment. Also, a full bladder may artiicially elongate the cervix and compress the lower uterine segment to give the impression that the placenta overlies the cervix. If placental location remains in question, then transvaginal sonography is the most accurate method of assessment (Fig. 41-23). It is safe, even when there is bleeding.


Obstentrics_Williams

Obstentrics_Williams. Accuracy depends on the sonographic technique used. In a comprehensive study, the internal os was visualized in all cases with transvaginal sonography but in only 30 percent with transabdominal sonography (Farine, 1988). As discussed, according to the Fetal Imaging Workshop, if the placental edge is <2 cm from the internal os, but not covering it, the placenta is considered low lying (Reddy, 2014). In the absence of any other indication, sonography need not be frequently repeated simply to document placental position. At Parkland, women with a placenta previa identiied at 18 to 22 weeks' gestation with a prior cesarean delivery are evaluated again at 28 weeks and those without at 32 weeks. Restriction of activity is not necessary unless a previa persists beyond 28 weeks or if clinical findings such as bleeding or contractions develop before this time. At 32 weeks' gestation, if the placental edge is still <2 cm from the os, then transvaginal sonography is repeated at 36 weeks.


Obstentrics_Williams

Obstentrics_Williams. Using MR imaging, several investigators have reported excellent results in visualizing placental abnormalities. hat said, it is unlikely that this technique will replace sonography for routine evaluation anytime soon. However, MR imaging has proved useful for evaluation of morbidly adherent placenta (p. 780).


Obstentrics_Williams

Obstentrics_Williams. Women with a placenta previa are managed based on their individual clinical circumstances. Three prominent factors include fetal age and maturity, labor, and bleeding severity. In one study of 214 women with a previa, 43 percent had an emergency delivery, and half of these were preterm (Ruiter, 2015). But, if the fetus is immature and active bleeding subsides, close observation in an obstetrical unit is indicated. Data are sparse regarding tocolytic administration for uterine contractions. Although robust randomized trials are lacking, Bose and colleagues (201r1) recommend that if tocolytics are given, they be limited to 48 hours of administration. We categorically recommend against their use in this setting.


Obstentrics_Williams

Obstentrics_Williams. Ater bleeding has ceased for approximately 2 days and the fetus is judged to be healthy, a woman can usually be discharged home with instructions for "pelvic rest." Importantly, the woman and her family must ully appreciate the possibility of recurrent bleeding and be prepared for immediate transport back to the hospital. In other cases, prolonged hospitalization may be ideal.


Obstentrics_Williams

Obstentrics_Williams. FIGURE 41 -23 Placenta previa. A. In this transvaginal image at 34 weeks' gestation, the anterior placenta completely covers the internal cervical os outlined by arrows. B.This transvaginal image at 34 weeks' gestation depicts a posterior placenta (arrow) that just reaches the level of the internal cervical os. (Reproduced with permission from Cunningham FG: Placenta previa and morbidly adherent placenta. In Yeomans ER, Hoffman BL, Gilstrap LC III, et al (eds): Cunningham and Gilstrap's Operative Obstetrics, 3rd edition. New York, McGraw-Hili Education,o201o7b.) he frequency of emergency delivery in women with pla centa previa ranges from 25 to 40 percent (Gibbins, 2018;


Obstentrics_Williams

Obstentrics_Williams. Kassir, 2017). But, in properly selected patients, long-term inpatient care does not appear to add beneits compared with outpatient management (Neilson, 2003). In one random ized study of 53 women who had a bleeding previa at 24 to 36 weeks' gestation, maternal or fetal morbidity rates did not difer between management method (Wing, 1996). Of all study women, 60 percent had recurrent bleeding, and half eventually required expeditious cesarean delivery.


Obstentrics_Williams

Obstentrics_Williams. For women who are near term and who are not bleeding, plns re made for scheduled cesarean delivery. Timing balances fetal immaturity risks against antepartum hemorrhage. One NIH workshop suggested elective delivery at 36 to 37 completed weeks' gestation (Spong, 2011). he Society for Maternal-Fetal Medicine (2017) recommends delivery between 34 and 37 weeks. At Park land Hospital, we usually perform elective cesarean delivery at 38 weeks. With a suspected morbidly adherent placenta, delivery is recommended at 34 to 35 completed weeks by the NIH workshop (p. 781). Our practice is to schedule delivery at 36 completed weeks.


Obstentrics_Williams

Obstentrics_Williams. Practically all women with placenta previa undergo cesarean delivery. Many surgeons recommend a vertical laparotomy incision to provide rapid entry in cases with torrential bleeding or operating space if hysterectomy is required. As discussed, cesarean delivery is emergently performed in more than half because of hemorrhage, for which about a fourth require blood transfusion (Boyle, 2009; Sabourin, 2012). Although a low transverse hysterotomy is usually possible, this may cause fetal bleeding if the placenta is implanted anteriorly and the placenta is incised. In such cases, fetal delivery should be expeditious (Silver, 2015a). A vertical uterine incision may be preferable in some instances. In either case, even when the incision extends through the placenta, maternal or fetal outcomes are rarely compromised.


Obstentrics_Williams

Obstentrics_Williams. Following placental removal, the placenta site may bleed uncontrollably due to poorly contracted smooth muscle, which is characteristic of the lower uterine segment. If hemostasis at the placental implantation site cannot be obtained by adequate uterotonic administration and pressure, it can be oversewn with O-chromic sutures. Cho and associates (1991) described interrupted O-chromic sutures at I-em intervals to form a circle around the bleeding portion of the lower segment to control hemorrhage. Others have reported success with compression sutures that traversed and compressed the anterior and posterior uterine wall (Kayem, 2011; Penotti, 2012).


Obstentrics_Williams

Obstentrics_Williams. Of other methods, Bakri or Foley balloon tamponade used alone or coupled with compression sutures has been described (Albayrak, 2011; Diemert, 2012; Kumru, 2013). Law and coworkers (2010) successfully used a hemostatic gel. Other surgical options are bilateral uterine or internal iliac artery ligation, illustrated later (p. 792). Finally, pelvic artery embolization has also gained acceptance. If these more conservative methods fail and bleeding is brisk, hysterectomy is necessary. Placenta previa-especially with an abnormally adherent placenta-currently is the most frequent and other institutions Qakobsson, 2015; Wong, 2011). When there is no associated accrete syndrome, the reported incidence of hysterectomy is 2 percent (Gibbins, 2018).


Obstentrics_Williams

Obstentrics_Williams. hus, it is not possible to accurately estimate the efect on the hysterectomy rate from previa alone without considering the associated accrete syndromes. Again, or women whose pla centa previa is implanted anteriory at the site of a prior uterine incision, the likelihood of an associated morbidy adherent placenta and need or hysterectomy is increased. In a study of 318 peri partum hysterectomies performed in the United Kingdom, 40 percent were done for abnormal placentation (Knight, 2007). Similar results were reported for 211 hysterectomies from the Nordic Obstetric Surveillance Study Qakobsson, 2015). At Parkland Hospital, 44 percent of cesarean hysterectomies were placenta (Wortman, 2015). The technique for peripartum hys terectomy is described in Chapter 30 (p. 580). ute substantively to maternal morbidity and mortality rates. he maternal mortality ratio is increased approximately threefold for women with a placenta previa (Gibbins, 2018; Oyelese, 2006).


Obstentrics_Williams

Obstentrics_Williams. ute substantively to maternal morbidity and mortality rates. he maternal mortality ratio is increased approximately threefold for women with a placenta previa (Gibbins, 2018; Oyelese, 2006). In another report of 5367 maternal deaths in the United States from 2006 to 2013, placenta previa alone accounted for nearly 3 percent of deaths from hemorrhage (Creanga, 2015, 2017).


Obstentrics_Williams

Obstentrics_Williams. In another report of 5367 maternal deaths in the United States from 2006 to 2013, placenta previa alone accounted for nearly 3 percent of deaths from hemorrhage (Creanga, 2015, 2017). The report from the Consortium on Safe Labor emphasizes the ongoing perinatal morbidity with placenta previa (Lai, 2012). Preterm delivery continues to be a major cause of perinatal death (N0rgaard, 2012). In deliveries with placenta previa in the United States in 1997, the neonatal mortality rate was threefold higher than that in unafected pregnancies and stemmed primarily from preterm delivery (Salihu, 2003). Ananth and colleagues (2003) reported a comparably elevated risk of neonatal death even for fetuses who delivered at term. This is at least partially related to the fetal anomaly rate, which is two-to threefold higher in pregnancies with placenta previa (Crane, 1999).


Obstentrics_Williams

Obstentrics_Williams. The association of fetal-growth restriction with placenta previa is likely minimal ter controlling for gestational age. In a populationbased cohort of more than 500,000 singleton births, Ananth and associates (2001) found that most low-birthweight newborns associated with placenta previa resulted from preterm birth. Harper and coworkers (2010) reported similar indings from a cohort of nearly 58,000 women. In contrast, at least two studies reported a greater risk for fetal-growth restriction (iisanen, 2014; Weiner, 2016). The term morbidy adherent placenta describes aberrant placentation characterized by abnormally implanted, invasive, or adhered placenta. We also refer to these disorders collectively as accrete syndromes and use these terms interchangeably. Derivation of accrete comes from the Latin ac-+ crescere-to adhere or become attached to (Benirschke, 2012).


Obstentrics_Williams

Obstentrics_Williams. In the accrete syndromes, abnormal placental adherence to the myometrium stems in part from partial or total absence of the decidua basalis and imperfect development of the ibrinoid or Nitabuch layer, described in Chapter 5 (p. 86). If the decidual spongy layer is lacking either partially or totally, then the physiological line of cleavage is absent, and some or all cotyledons are densely anchored. Microscopically, placental villi attach to smooth muscle ibers rather than to decidual cells. This decidual deiciency then prevents normal placental separation after delivery. he surface area of the implantation site involved and the depth of trophoblastic tissue ingrowth are variable between women, but all afected placentas can potentially cause signiicant hemorrhage.


Obstentrics_Williams

Obstentrics_Williams. Substantiated data now suggest that accrete syndromes are not solely caused by this anatomical layer deficiency (Duzyj, 2017; T antbirojn, 2008). Indeed, the cytotrophoblasts may control decidual invasion through factors such as angiogenesis (Duzyj, 2015; Goh, 2016; Wehrum, 2011). Also, accrete syndrome tissue specimens show "hyperinvasiveness" (Pri-Paz, 2012) . Myometrial ibers attached to the basal plate in an antecedent pregnancy are predictive markers for a subsequent FIGURE 41-24 Morbidly adherent placentas: A. Placenta accreta. B. Placenta increta. C. Placenta percreta. placenta accreta (Linn, 2015; Nliller, 2016). his implies an antecedent "constitutional endometrial defect" in most cases. The greater risk conveyed by previous surgical uterine trauma may be partially explained by an enhanced vulnerability to trophoblast invasion (Garmi, 2012; Gill, 2015; Jauniaux, 2017).


Obstentrics_Williams

Obstentrics_Williams. his association with prior trauma is reinforced by the close relationship between cesarean-scar pregnancy (CSP) and later development of placenta accreta in the same pregnancy. Indeed, accruing evidence suggests that CSP and accrete syndromes lie on a spectrum and that CSP is a precursor, as both share the same histopathology (Happe, 2018; Timor-Tritsch, 2014). CSP frequency has been reported to approximate 1 in 2000 pregnancies (Berhie, 2015; Rotas, 2006). Described in Chapter 19 (p. 381), early rupture and hemorrhage are not uncommon with CSP, and women often elect pregnancy-terminating interventions to avoid these (Michaels, 2015; Timor-Tritsch, 2015). Variants of the morbidly adherent placenta are classified by the depth of trophoblastic growth (Figs. 41-24 and 41-25).


Obstentrics_Williams

Obstentrics_Williams. Variants of the morbidly adherent placenta are classified by the depth of trophoblastic growth (Figs. 41-24 and 41-25). FIGURE 41-25 Varying degrees of myometrial invasion with the accrete syndromes. Incisions begin on the serosal surface and extend through to the placenta. A. In this case, the myometrium (M) shows minimal invasion by the placenta (P). S = uterine serosa. B. A greater degree of myometrial invasion is seen here. C. In this example, the placenta (backets) extends to the serosal edge, held by the surgeon's hand. No myometrium remains at this site. (Reproduced with permission from Dr. C. Edward Wells in Cunningham FG: Placenta previa and morbidly adherent placenta. In Yeomans ER, Hoffman BL, Gilstrap LC III, et al (eds): Cunningham and Gilstrap's Operative Obstetrics, 3rd edition. New York, McGraw-Hili Education, 2017b.)


Obstentrics_Williams

Obstentrics_Williams. Placenta accreta indicates that villi are attached to the myome trium. With placenta in creta , villi actually invade the myome trium, and placenta percreta defines villi that penetrate through the myometrium and to or through the serosa (Bailit, 2015; Silver, 20 15a). In clinical practice, these three variants are encountered in an approximate ratio of 80:15:5, respectively (Wong, 2008). In all three varieties, abnormal adherence may involve all lobules-total placenta accreta. If all or part of a single lobule is abnormally attached, it is described as a ocal placenta accreta. Histological diagnosis cannot be made from the placenta alone, and myometrial samples are necessary for confirmation (Benirschke, 2012) .


Obstentrics_Williams

Obstentrics_Williams. he frequency of accrete syndromes was 1 in 20,000 births almost 100 years ago (McKeogh, 1951). As late as 1971, Hell man and Pritchard in the 14th edition of Williams Obstetrics described accreta to be the subject of case reports. Since then, the incidence has grown remarkably in direct relationship to the rising cesarean delivery rate. For example, incidence was 1 in 2500 births in the 1980s, but it was 1 per 731 births in the report from the MFMU Network comprising 115,502 women (Bailit, 2015). And a Canadian study of more than 570,000 births found an incidence of 1 in 700 deliveries (Mehrabadi, 2015). In the Nationwide Inpatient Sample, the prevalence of accreta was 3.7 per 1000 births-1 per 270 (Mogos, 2016).


Obstentrics_Williams

Obstentrics_Williams. This rising frequency has made accrete syndromes one of the most formidable problems in obstetrics. In one review of 5367 pregnancy-related maternal deaths in the United States from 2006 to 2013, 13 percent were due to hemorrhage caused by accrete syndromes (Creanga, 2015, 2017). In addition, they are a leading cause of hemorrhage and emergency peripartum hysterectomy (Awan, 2011; Eller, 2011; Rossi, 2010). The American College of Obstetricians and Gynecologists (2017 c) and the Society for Maternal-Fetal Medicine (2010) have taken the lead to address and optimize management. In subsequent pregnancies following placenta accreta, recurrence risks are high. Women in whom hysterectomy is avoided have an estimated 20-percent incidence of recurrence (Cunningham, 2016; Roeca, 2017). In addition, some evidence shows that these women have greater risks for previa, uterine rupture, and hysterectomy (Eshkoli, 2013).


Obstentrics_Williams

Obstentrics_Williams. hese are similar in many aspects to those for placenta previa (p. 774). That said, the two most important risk factors are an associated previa, a prior cesarean delivery, and more likely a combination of the two (Kia', 2014). A classical hysterotomy incision has a higher risk for a subsequent accrete placenta (Gyami-Bannerman, 2012). In fact, almost half of women with a prior cesarean delivery had myometrial fibers seen microscopically adhered to the placenta (Hardardottir, 1996; Miller, 2016). An associated previa confers an even higher risk. his is shown in Figure 41-26, and the astonishing increase in frequency of associated accrete syndromes is apparent with a concomitant previa. FIGURE 41-26 Frequency of morbidly adherent placenta in women with 1 to 5 prior cesarean deliveries (CDs) now with a previa. (Data from Silver, 2006.)


Obstentrics_Williams

Obstentrics_Williams. FIGURE 41-26 Frequency of morbidly adherent placenta in women with 1 to 5 prior cesarean deliveries (CDs) now with a previa. (Data from Silver, 2006.) Dysfunctional decidual formation also may follow any other type of myometrial trauma such as curettage or endometrial ablation (Benirschke, 2012; Gill, 2015). Even without a prior hysterotomy, coexisting placenta previa is additive to frequency, and in one study, 10 percent ofsuch women with a previa had an associated accrete syndrome. A shorter cervical length with placenta accrete syndromes did not confer a greater risk for preterm delivery (Rae, 2017).


Obstentrics_Williams

Obstentrics_Williams. Another risk marker became apparent with widespread use of MSAFP and human chorionic gonadotropin (hCG) screening for neural-tube defects and aneuploidies. In one study of more than 9300 women screened at 14 to 22 weeks' gestation, the risk for accrete syndromes was eightfold higher with MSAFP levels >2.5 110M, and it was increased fourfold with maternal serum free �-hCG levels >2.5 MoM (Hung, 1999). In cases offirst-and second-trimester accrete syndromes, there is usually hemorrhage that is the consequence ofcoexisting placenta previa. Such bleeding will typically prompt evaluation and management. In some women who do not have an associated previa, accreta may not be identiied until third-stage labor when an adhered placenta is encountered. Unfortunately, imaging modalities are less than perfect to identiy all of these placentas early.


Obstentrics_Williams

Obstentrics_Williams. Ideally, sonography is used for antepartum identiication of abnormal placental ingrowth (Chantraine, 2013; Jauniaux, 2016; Reddy, 2014; Tam Tam, 2012). Happe and colleagues (2018) found that first-trimester measurement of the smallest myometrial thickness can be used to predict the necessity for peripartum hysterectomy with an accrete syndrome. Other indings include loss of the normal hypoechoic retroplacental zone between the placenta and uterus, placental vascular lacunae, and placental bulging into the posterior bladder wall (Fig. 41-27). Using these criteria, Warshak and associates (2006) calculated the following values: sensitivity of 77 percent; specificity of 96 percent; positive-predictive creta shows mUltiple and massive placental "lakes" or "lacunae". (Reproduced with permission from Dr. Martha Rac in Cunningham FG: Placenta previa and morbidly adherent placenta. In Yeomans ER, Hofman BL, Gilstrap LC III, et al (eds): Cunningham and Gilstrap's Operative Obstetrics, 3rd


Obstentrics_Williams

Obstentrics_Williams. from Dr. Martha Rac in Cunningham FG: Placenta previa and morbidly adherent placenta. In Yeomans ER, Hofman BL, Gilstrap LC III, et al (eds): Cunningham and Gilstrap's Operative Obstetrics, 3rd edition. New York, McGraw-Hili Education, 201o7b.) value of 98 percent. Similar values are cited by the American College ofObstetricians and Gynecologists (2017c) and others (Chalubinski, 2013; Elhawary, 2013; Maher, 2013).


Obstentrics_Williams

Obstentrics_Williams. Despite these findings, some investigators report less spectacular results with sonography aauniaux, 2016; Primo, 2014). Bowman and colleagues (2014)r.described the sensitivity of sonography to be 54 percent; specificity, 88 percent; positivepredictive value, 82 percent; negative-predictive value, 65 percent; and accuracy, 65 percent. Location afects sonographic accuracy. In one study, the detection rate was 90 percent for anterior placenta accreta compared with 50 percent for posterior wall ones (Pilloni, 2016). Nageotte (2014) concluded that identiication of the morbidly adherent placenta with sonography should be interpreted along with clinical and operative indings.


Obstentrics_Williams

Obstentrics_Williams. Better results have been reported by some using threedimensional (3-D) sonography and power Doppler (Collins, 2015; Doyle, 2015). We too have found that the addition of Doppler color low mapping is highly predictive ofmyometrial invasion (Fig. 41-28). This is suspected if the distance between the uterine serosa-bladder wall interface and the retroplacental vessels measures < 1 mm and if there are large intraplacental lacunae (Rae, 2015a; Twicler, 2000). Similarly, Cali and associates (2013) reported that hypervascularity of the uterine serosa-bladder wall interface had the highest positive-and negative-predictive values for placenta percreta.


Obstentrics_Williams

Obstentrics_Williams. MR imaging can be added to outline anatomy and to identiy invasion of adjacent structures, including possible ureteral involvement (Chalubinski, 2013; Reddy, 2014). Although gadolinium is usually not added during pregnancy, this contrast may enhance images (Millischer, 2017). Lax and coworkers (2007) described three MR imaging findings that suggest accreta: uterine bulging, heterogeneous signal intensity within the placenta indicative of lacunae, and dark intraplacental bands on T2-weighted imaging. Some recommend use of MR imaging if sonography results are inconclusive or there is a posterior previa (American College of Obstetricians and Gynecologists, 2017c; Silver, 2015a). FIGURE 41-28 Transvaginal sonogram of placental invasion with a morbidly adherent placenta. Retroplacental vessels (white arrows) invade the myometrium and obscure the bladder-serosal interface. Abnormal intraplacental venous lakes (black arrowheads) are commonly seen in this setting.