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Obstentrics_Williams. Several reports attest to the safety of vaginal delivery of second noncephalic twins whose birthweight is > 1500g. A French multicenter study of 5915 twin pregnancies illustrates this (Schmitz, 2017). Of these, 25 percent had a planned cesarean delivery. The other 75 percent with a first twin cephalic and gestational age > 32 weeks had a planned trial of vaginal delivery, which was successful in 80 percent. Interestingly, perinatal mortality and morbidity rates were significantly higher in the planned cesarean delivery group delivered <37 weeks-5.2 versus 3.0 percent, respectively. Fox and colleagues (2014) reported outcomes in 287 diamnionic twin pregnancies, of which 130 underwent a planned vaginal delivery. Only 15 percent of the planned vaginal delivery group underwent a cesarean delivery. Perinatal outcomes were similar in both groups. hese two studies included only those fetuses with estimated weightsr> 1500 g. Notably, comparable or even better fetal outcomes with vaginal


Obstentrics_Williams

Obstentrics_Williams. delivery. Perinatal outcomes were similar in both groups. hese two studies included only those fetuses with estimated weightsr> 1500 g. Notably, comparable or even better fetal outcomes with vaginal delivery have been reported with neonates weighing < 1500 g compared with those weighing > 1500 g (Caukwell, 2002; Davidson, 1992).


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Obstentrics_Williams. Other investigators advocate cesarean delivery for both members of a cephalic-noncephalic twin pair (Armson, 2006; Hofmann, 2012). Yang and coworkers (2005a,b) studied 15,185 cephalicnoncephalic twin pairs. he risks of asphyxia-related neonatal deaths and morbidity were higher in the group in which both twins were delivered vaginally compared with the group in which both twins underwent cesarean delivery.


Obstentrics_Williams

Obstentrics_Williams. To add insight into the clinical complexities just discussed, a randomized trial was designed by the Twin Birth Study Collaborative Group from Canada. he study results described by Barrett and associates (2013) included 2804 women carrying a presumed diamnionic twin pregnancy with the irst fetus presenting cephalic. Women were randomly assigned between 32 and 38 weeks' gestation to planned cesarean or vaginal delivery. The time from randomization to delivery-12.4 versus 13.3 days, the mean gestational age at delivery-36.7 versus 36.8 weeks, and use of regional analgesia-92 versus 87 percent, were similar in both groups. Salient maternal and perinatal outcomes are shown in Table 45-3. No significant diferences in outcomes were noted between the two groups of women. Although risks to mother or fetuses with planned vaginal delivery in these circumstances were not increased, Greene (2013) posited that this trial would have only modest efects on the cesarean delivery rate of women with


Obstentrics_Williams

Obstentrics_Williams. or fetuses with planned vaginal delivery in these circumstances were not increased, Greene (2013) posited that this trial would have only modest efects on the cesarean delivery rate of women with twins.


Obstentrics_Williams

Obstentrics_Williams. Breech Presentation of First Twin Problems with the first twin presenting as a breech are similar to those encountered with a singleton breech fetus. hus, major diiculties may develop in the following settings. First, the fetus may be large, and the aftercoming head is larger than the birth canal. Second, the fetal body can be small, and delivery of the extremities and trunk through an inadequately efaced and dilated cervix causes the relatively larger head to become trapped above the cervix. his is more likely when there is significant disproportion between the head and body. Examples are preterm or growth-restricted fetuses or those with Serious morbidity 1.3% 1.3% Possible 0.5% 0.4% Intubation 1.0% 0.6% alncludes coma; stupor; hyperalert, drowsy or lethargic; or ::2 seizu res. Data from Barrett, 20ln3. macrocephaly from hydrocephaly. Last, umbilical cord prolapse is an ever-present risk.


Obstentrics_Williams

Obstentrics_Williams. Data from Barrett, 20ln3. macrocephaly from hydrocephaly. Last, umbilical cord prolapse is an ever-present risk. If these problems are anticipated or identiied, cesarean delivery is often preferred with a viable-sized fetus. But even without these problems, many obstetricians perform cesarean delivery if the irst twin presents as breech. This is despite data that support the safety of vaginal delivery. Specifically, Blickstein and associates (2000) reported experiences from 13 European centers with 613 twin pairs and the first twin presenting breech. Vaginal delivery was attempted in 373 of these cases and was successful in 64 percent. Cesarean delivery of the second twin was done in 2.4 percent. here was no diference in the rate of 5-minute Apgar scores <7 or of mortality in breech-presenting first twins who weighed at least 1500 g. Details of techniques for delivery of a breech presentation are described in Chapter 28 (p. 544).


Obstentrics_Williams

Obstentrics_Williams. Twin fetuses may become locked together during delivery if the irst presents breech and the second cephalic. As the breech of the irst twin descends through the birth canal, the chin locks between the neck and chin of the second cephalic-presenting cotwin. This phenomenon is rare, and Cohen and coworkers (1965) described it only once in 817 twin gestations. Cesarean delivery should be considered when the potential for locking is identiied. • Vaginal Delivery of the Second Twin


Obstentrics_Williams

Obstentrics_Williams. • Vaginal Delivery of the Second Twin Following delivery of the first twin, the presenting part of the second twin, its size, and its relationship to the birth canal should be quickly and careully ascertained by combined abdominal, vaginal, and at times, intrauterine examination. Sonography is a valuable aid. If the fetal head or the breech is fixed in the birth canal, moderate undal pressure is applied and membranes are ruptured. Immediately aterward, digital examination of the cervix is repeated to exclude cord prolapse. Labor is allowed to resume. If contractions do not begin within approximately 10 minutes, dilute oxytocin may be used to stimulate contractions.


Obstentrics_Williams

Obstentrics_Williams. In the past, the safest interval between delivery of the irst and second twins was frequently cited as <30 minutes. Rayburn and colleagues (1984) and others have shown that if continuous fetal monitoring is used, a good outcome is usually achieved even if this interval is longer. A direct correlation between worsening umbilical cord blood gas values and increasing time between delivery of irst and second twins has been shown (Leung, 2002; Stein, 2008). From review of 239 twin gestations, Gourheux and associates (2007) determined that mean umbilical arterial pH was signiicantly lower after the delivery interval exceeded 15 minutes. In a study of more than 175,000 twin pairs, Cheng and colleagues (2017) reached similar conclusions for maternal and perinatal morbidity.


Obstentrics_Williams

Obstentrics_Williams. If the occiput or breech presents immediately over the pelvic inlet, but is not ixed in the birth canal, the presenting part can often be guided into the pelvis by one hand in the vagina, while a second hand on the uterine fundus exerts moderate pressure caudally. A presenting shoulder may be gently converted into a cephalic presentation. Alternatively, with abdominal manipulation, an assistant can guide the presenting part into the pelvis. Sonography can aid guidance and allow heart rate monitoring. Intrapartum external version of a noncephalic second twin has also been described.


Obstentrics_Williams

Obstentrics_Williams. If the occiput or breech is not over the pelvic inlet and cannot be so positioned by gentle pressure or if appreciable uterine bleeding develops, delivery of the second twin can be problematic. To obtain a favorable outcome, an obstetrician skilled in intrauterine fetal manipulation and anesthesia personnel skilled in providing anesthesia to efectively relax the uterus for vaginal delivery of a noncephalic second twin are essential (American College of Obstetricians and Gynecologists, 2016). To take maximum advantage of the dilated cervix before the uterus contracts and the cervix retracts, delay should be avoided. Prompt cesarean delivery of the second fetus is preferred if no one present is skilled in the performance of internal podalic version or if anesthesia that will provide efective uterine relaxation is not immediately available.


Obstentrics_Williams

Obstentrics_Williams. With internal podalic version, a fetus is turned to a breech presentation using the hand placed into the uterus (Fig. 45-26). he obstetrician grasps the fetal feet to then efect delivery by breech extraction (Chap. 28, p. 548). As mentioned earlier, Fox and associates (2010) described a strict protocol for management of the delivery of the second twin, which included internal podalic version. hey reported that none of the 110 women who delivered the irst twin vaginally underwent a cesarean delivery for the second twin. Chauhan and coworkers (1r995) compared outcomes of 23 second twins delivered by internal podalic version and breech extraction with those of 21 who underwent external cephalic version. Breech extraction was considered superior to external version because less fetal distress developed. Additional information and illustrations of this procedure are found in Cunningham and Gilstrap 5 Operative Obstetrics, 3rd edition (Yeomans, 2017).


Obstentrics_Williams

Obstentrics_Williams. FIGURE 45-26 Internal podalic version. Upward pressure on the head by an abdominal hand is applied as downward traction is exerted on the feet. Any attempt to deliver twins vaginally in a woman who has previously undergone one or more cesarean deliveries should be carefully considered. Some studies support the safety of attempting a vaginal birth after cesarean delivery (VBAC) for selected women with twins (Cahill, 2005; Ford, 2006; Varner, 2005). According to the American College of Obstetricians and Gynecologists (2017 c), no evidence currently suggests an increased risk of uterine rupture, and women with twins and one previous cesarean delivery with a low transverse incision may be considered candidates for trial of labor. At Parkland Hospital, we recommend repeat cesarean delivery.


Obstentrics_Williams

Obstentrics_Williams. Several unusual intraoperative problems can arise during cesarean delivery of twins or higher-order multiples. Supine hypotension is common, and thus gravidas are positioned in a left lateral tilt to delect uterine weight of the aorta (Chap. 4, p. 63). A low transverse hysterotomy is preferable if the incision can be made large enough to allow atraumatic delivery of both fetuses. Piper forceps can be used if the second twin is presenting breech (Fig. 28-11, p. 547). In some cases, a vertical hysterotomy beginning as low as possible in the lower uterine segment may be advantageous. For example, if a fetus is transverse with its back down and the arms are inadvertently delivered irst, it is much easier and safer to extend a vertical uterine incision upward than to extend a transverse incision laterally or to make a "T" incision vertically.


Obstentrics_Williams

Obstentrics_Williams. Fetal heart rate monitoring during labor with triplet pregnancies is challenging. A scalp electrode can be attached to the presenting fetus, but it is diicult to ensure that the other two fetuses are each being monitored separately. With vaginal deliv ery, the first neonate is usually born with little or no manipula tion. Subsequent fetuses, however, are delivered according to the presenting part. his often requires complicated obstetri cal maneuvers such as total breech extraction with or without internal podalic version or even cesarean delivery. Associated with malposition of fetuses is an increased incidence of cord prolapse. Moreover, reduced placental perfusion and hemor rhage from separating placentas are more likely during delivery. For all these reasons, many clinicians believe that preg cesarean delivery (American College of Obstetricians and


Obstentrics_Williams

Obstentrics_Williams. For all these reasons, many clinicians believe that preg cesarean delivery (American College of Obstetricians and Gynecologists, 2016). Vaginal delivery is reserved for those cir cumstances in which survival is not expected because fetuses are delivery hazardous to the mother. Others believe that vaginal delivery is safe under certain circumstances. Grobman and asso delivery completion rates of 88 and 84 percent, respectively, in women carrying triplets who underwent a trial of labor. Neo natal outcomes did not difer from those of a matched group of triplet pregnancies undergoing elective cesarean delivery. Con versely, in one review of more than 7000 triplet pregnancies, vaginal delivery was associated with a higher perinatal mortality rate (Vintzeleos, 2005). Lappen and coworkers (2016) reported similar results from the database of the Consortium on Safe


Obstentrics_Williams

Obstentrics_Williams. Labor. They recommended prelabor cesarean delivery for trip lets. Importantly, the overall cesarean delivery rate among trip lets was 95 percent. In some cases of higher-order multi fetal gestation, reduction of the fetal number to two or three improves survival of the remaining fetuses. Selective reduction implies early pregnancy intervention, whereas selective termination is performed later. he procedure should be performed by an operator skilled and experienced in sonographically guided procedures. Reduction of a selected fetus or fetuses in a multichorionic multifetal gestation may be chosen as a therapeutic intervention to enhance survival of the remaining fetuses (American College of Obstetricians and Gynecologists, 20 17b). One metaanalysis of nonrandomized prospective studies indicates that pregnancy reduction to twins compared with expectant management is associated with lower rates of maternal complications, preterm birth, and neonatal death (Dodd, 2004, 2012).


Obstentrics_Williams

Obstentrics_Williams. Pregnancy reduction can be performed transcervically, transvaginally, or transabdominally, but the transabdominal route is usually easiest. Transabdominal fetal reductions are typically performed between 10 and 13 weeks' gestation. This gestational age is chosen because most spontaneous abortions have already occurred, the remaining fetuses are large enough to be evaluated sonographically, the amount of devitalized fetal tissue remaining after the procedure is small, and the risk of aborting the entire pregnancy as a result of the procedure is low. The smallest fetuses and any anomalous fetuses are cho sen for reduction. Potassium chloride is then injected under sonographic guidance into the heart or thorax of each selected fetus. Care is used to avoid entry or traverse the sacs of fetuses selected for retention.


Obstentrics_Williams

Obstentrics_Williams. pregnancies from 1995 to 1998. he pregnancy loss rate var ied from a low of 4.5 percent for triplets that were reduced to twins. The loss rate rose with each addition to the starting num ber of fetuses and peaked at 15 percent for six or more fetuses. Operator skill and experience are believed responsible for the low and declining rates of pregnancy loss. With the identification of multiple fetuses discordant for struc tural or genetic abnormalities, three options are available: abor tion of all fetuses, selective termination of the abnormal fetus, or pregnancy continuation. Because anomalies are typically not discovered until the second trimester, selective termination is greater risk. This procedure is therefore usually not performed unless the anomaly is severe but not lethal. In some cases, ter mination is considered because the abnormal fetus may jeopar dize the normal one.


Obstentrics_Williams

Obstentrics_Williams. Prerequisites to selective termination include a precise diagnosis for the anomalous fetus and absolute certainty of fetal location. Unless a special procedure such as umbilical cord interruption is used, selective termination should be performed only in multichorionic multifetal gestations to avoid damaging the surviving fetuses (Lewi, 2006). Roman and coworkers (2010) compared 40 cases of bipolar umbilical cord coagulation with 20 cases of radiofrequency ablation for treatment of complicated monochorionic multifetal gestations at midpregnancy. hey found similar survival rates of 87 and 88 percent, and a median gestational age > 36 weeks at delivery in both. Prefumo and colleagues (2013) reported their preliminary experience with microwave ablation of the umbilical cord for selective termination in two monochorionic twin pregnancies. One pregnancy aborted within 7 days, and the other resulted in a term singleton delivered at 39 weeks' gestation.


Obstentrics_Williams

Obstentrics_Williams. Evans and coworkers (1999) have provided the most comprehensive results to date on second-trimester selective termination for fetal abnormalities. A total of 402 cases were analyzed from eight centers worldwide. Included were 345 twin, 39 triplet, and 18 quadruplet pregnancies. Selective termination using potassium chloride resulted in delivery of a viable neonate or neonates in more than 90 percent of cases, with a mean age of 35.7 weeks at delivery. The entire pregnancy was lost in 7 percent of pregnancies reduced to singletons and in 13 percent of those reduced to twins. The gestational age at the time of the procedure did not appear to afect the pregnancy loss rate.


Obstentrics_Williams

Obstentrics_Williams. Before selective termination or reduction, a discussion should include the morbidity and mortality rates expected if the pregnancy is continued; the morbidity and mortality rates expected with surviving twins or triplets; and the risks of the procedure itself (American College of Obstetricians and Gynecologists, 2017b). Speciic risks of selective termination or reduction are: abortion of the remaining fetuses; (2) abortion or retention of the wrong fetus(es); (3) damage without death to a fetus; preterm labor; (5) discordant or growth-restricted fetuses; and (6) maternal complications. he last includes potential infection, hemorrhage, or disseminated intravascular coagulopathy because of retained products of conception. The final decision to continue the pregnancy without intervention, to terminate the entire pregnancy, or to elect selective termination is solely the patient' s (Chervenak, 2013).


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Obstentrics_Williams. Abel EL, Kruger ML: Maternal and paternal age and twinning in the United States, 2004-2008. J Perinat Med 40:237,t2012 Alexander JM, Leveno KJ, Rouse 0, et al: Cesarean delivery for the second twin. Obstet Gynecol 112(4):748, 2008 Alran S, Sibony 0, Luton 0, et al: Maternal and neonatal outcome of 93 consecutive triplet pregnancies with 71 % vaginal delivery. Acta Obstet Gynecol Scand 83:554, 2004 American College of Obstetricians and Gynecologists: Multifetal gestations: twin, triplets, and higher-order multifetal pregnancies. Practice Bulletin No. 169, October 2016, Reairmed 2016 American College of Obstetricians and Gynecologists: Delayed umbilical cord clamping after birth. Committee Opinion No. 684, January 2017a American College of Obstetricians and Gynecologists: Multifetal pregnancy reduction. Committee Opinion No. 719, September 2017b


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Obstentrics_Williams. American College of Obstetricians and Gynecologists: Vaginal birth after previous cesarean delivery. Practice Bulletin No. 115, August 2010, Reairmed 2017c American Sociery for Reproductive Medicine, Sociery for Assisted Reproductive Technology: Guidance on the limits to the number of embryos to transfer: a committee opinion. Fertil Sterilt107(4):901, 2017 Ananth CV, Chauhan SP: Epidemiology of twinning in developed countries. Semin Perinatol 36: 156, 2012 Ananth CV, Vintzileos M, Shen-Schwarz S, et al: Standards of birth weight in twin gestations stratiied by placental chorionicity. Obstet Gynecol 91(6):917,t1998 Andrews W, Leveno KJ, Sherman ML, et al: Elective hospitalization in the management of twin pregnancies. Obstet Gynecol 77:826, 1991 Antsaklis A, Fotodotis M, Sindos M, et al: Trends in twin pregnancies and mode of delivery during the last 30 years: inconsistency between guidelines and clinical practice. J Perinat Med 41(4):355,t2013


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Obstentrics_Williams. Obstet GynecoIt121(6):1318, 2013 Dashe ]S, Fernandez CO, Twickler DM: Utiliry of Doppler velocimetry in predicting outcome in twin reversed-arterial perfusion sequence. m ] Obstet Gynecol 185(1):135,t2001 Davidson L, Easterling TR, Jackson ]C, et a1: Breech extraction of low-birthweight second twins. Amt] Obstet Gynecol 166:497, 1992 de Castro H, Haas ], Schif E, et al: Trial of labour in twin pregnancies: a retrospective cohort study. B]OG 126(6):940,t2016 Denker HW: Comment on G. Herranz: The timing of monozygotic twinning: a criticism of the common model. Zygote (2013). Zygote 23(2):312,t2015 De Paepe ME, DeKoninck P, Friedman M:Vascular distribution patterns in monochorionic twin placentas. Placenta 26(6):471,t2005 Derbent A, Simavli S, Gumus I, et a1: Nifedipine for the treatment of preterm labor in twin and singleton pregnancies. Arch Gynecol Obstet 284:821, 2011 DeVoe LD: Antenatal fetal assessment: multi fetal gestation-an overview. Semin Perinatol 32:281, 2008


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Obstentrics_Williams. Semin Perinatol 32:281, 2008 Diamond MP, Legro RS, Coutifaris C, et al: Assessment of multiple intrauterine gestations from ovarian stimulation (AMIGOS) trial: baseline characteristics. Fertil Steril 103(4):962,t2015 Dickey RP, Taylor SN, Lu PY, et al: Spontaneous reduction of multiple pregnancy: incidence and efect on outcome. Am] Obstet GynecoIt186:77, 2002 Dodd ], Crowther C: Multifetal pregnancy reduction of triplet and higher order multiple pregnancies to twins. Fertil Steril 81 (5): 1420, 2004 Dodd ]M, Crowther CA: Reduction of the number of fetuses for women with a multiple pregnancy. Cochrane Database Syst Rev 10:CD003932, 2012 Dolapcioglu K, Gungoren A, Hakverdi S, et al: Twin pregnancy with a complete hydatidiform mole and co-existent live fetus: two case reportS and review of the literature. Arch Gynecol Obstet 279:431, 2009


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Obstentrics_Williams. Quintero A, Morales ), Allen MH, et al: Staging of twin-twin transfusion syndrome. J Perinatol 19:550, 1999 Rana 5, Hacker MR, Modest AM, et al: Circulating angiogenic factors and risk of adverse maternal and perinatal outcomes in twin pregnancies with suspected preeclampsia: novelty and signiicance. Hypertension 60:45t1,t2012 Ray B, Platt MP: Mortality of twin and singleton livebirths under 30 weeks' gestation: a population-based study. Arch Dis Child Fetal Neonatal Ed 94(2):F140, 2009 Rayburn WF, Lavin]P Jr, Miodovnik M, et al: Multiple gestation: time interval between delivery of the irst and second twins. Obstet Gynecol 63:502, 1984 Razavi AS, Chasen ST, Chambers F, et al: Maternal morbidity associated with labor induction in twin gestations. Abstract No. 733 Amt] Obstet Gynecol 216:5427,t2017 Rebarber A, Roman AS, Istwan N, et al: Prophylactic cerclage in the management of triplet pregnancies. Am] Obstet Gynecol 193: 1193, 2005


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Obstentrics_Williams. Rebarber A, Roman AS, Istwan N, et al: Prophylactic cerclage in the management of triplet pregnancies. Am] Obstet Gynecol 193: 1193, 2005 Record RG, McKeown T, Edwards ]H: An investigation of the diference in measured intelligence between twins and single births. Ann Hum Genet 34(1):11, 1970 Reddy UM, Abuhamad AZ, Levine 0, et al: Fetal imaging: executive summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, American Institute of Ultrasound in Medicine, American College of Obstetricians and Gynecologists, American College of Radiology, Society for Pediatric Radiology, and Society of Radiologists in Ultrasound Fetal Imaging workshop. Obstet Gynecol 123(5):1070,t2014 Reddy UM, Branum M, KlebanofA:Relationship of maternal body mass index and height to twinning. Obstet GynecoIt105(3):593, 2005


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Obstentrics_Williams. Reddy UM, Branum M, KlebanofA:Relationship of maternal body mass index and height to twinning. Obstet GynecoIt105(3):593, 2005 Roberts D, Dalziel 5: Antenatal corticosteroids for accelerating fetal lung maturation for women at risk of preterm birth. Cochrane Database Syst Rev 3:CD004454, 2006 Roberts D, Gates 5, Kilby M, et aI: Interventions for twin-twin transfusion syndrome: a Cochrane review. Ultrasound Obstet GynecoIt31:701, 2008 Robyr R, Lewi L, Salomon LJ, et I: Prevdence and management of late fetal complications following successful selective laser coagulation of chorionic plate anastomoses in twin-to-twin transfusion syndrome. Am J Obstet Gynecol 194:796, 2006 Rode L, Klein K, Nicolaides KH, et al: Prevention of preterm delivery in twin gestations (PREDICT): a multicenter, randomized, placebo-controlled trial on the efect of vaginal micronized progesterone. Ultrasound Obstet Gynecol 38:272, 2011


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Obstentrics_Williams. Roman A, Papanna R, Johnson A, et aI: Selective reduction in complicated monochorionic pregnancies: radiofrequency ablation vs bipolar cord coagulation. Ultrasound Obstet Gynecol 36:37, 2010 Roman A, Rochelson B, Martinelli P, et aI: Cerclage in twin pregnancy with dilated cervix between 16 to 24 weeks of gestation: retrospective cohort study. mJ Obstet GynecoIt215(1):98.e1, 2016 Roman AS, Saltzman DH, Fox N, et al: Prophylactic cerclage in the management of twin pregnancies. mJ PerinatoIt30(9):751, 2013 Romero R, Conde-Agudelo A, EI-Refaie W, et aI: Vaginal progesterone decreases preterm birth and neonatal morbidity and mortality in women with a twin gestation and a short cervix: an updated meta-analysis of individual patient data. Ultrasound Obstet GynecoIt49(3):303, 2017 Ronalds GA, De Stavola BL, Leon DA: he cognitive cost of being a twin: evidence from comparisons within families in the Aberdeen children of the 1950s cohort study. BMJ 331(7528):1306, 2005


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Obstentrics_Williams. Ronalds GA, De Stavola BL, Leon DA: he cognitive cost of being a twin: evidence from comparisons within families in the Aberdeen children of the 1950s cohort study. BMJ 331(7528):1306, 2005 Rossi AC, D'Addario V: Laser therapy and serial amnioreduction as treatment for twin-twin transfusion syndrome: a metaanalysis and review of literature. mJ Obstet Gynecol 198:147,t2008 Rossi AC, D'Addario V: Umbilical cord occlusion for selective feticide in complicated monochorionic twins: a systematic review of literature. Am J Obstet GynecoIt200(2):123,t2009 Rossi AC, Mullin PM, Chmait RH: Neonatal outcomes of twins according to birth order, presentation and mode of delivery: a systematic review and meta-analysis. BJOG 118(5):523,t2011 Rothman KJ: Fetal loss, twinning and birthweight ater orl contraceptive use. N Engl J Med 297:468, 1977 Rouse DJ, Caritis SN, Peaceman M, et al: A trial of 17alpha-hydroxyprogesterone caproate to prevent prematurity in twins. N Engl J Med 357:454,t2007


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Obstentrics_Williams. N Engl J Med 297:468, 1977 Rouse DJ, Caritis SN, Peaceman M, et al: A trial of 17alpha-hydroxyprogesterone caproate to prevent prematurity in twins. N Engl J Med 357:454,t2007 Rouse DJ, Skopec GS, Zlatnik FJ: Fundal height as a predictor of preterm twin delivery. Obstet GynecoI81:211, 1993 Salem SY, Kibel M, Asztalos E, et al: Neonatal outcomes of low-risk, latepreterm twins compared with late-preterm singletons. Obstet Gynecol 130(3):582,t2017 Salomon LJ, Ortqviast L, Aegerter P, et aI: Long-term developmental follow-up of infants who participated in a randomized clinical trial of amniocentesis vs laser photocoagulation for the treatment of twin-to-twin transfusion syndrome. mJ Obstet Gynecol 203(5):444.el, 2010 Schmitz T, Prunet C, Azria E, et aI: Association between planned cesarean delivery and neonatal mortality and morbidity in twin pregnancies. Obstet GynecoIt129(6):986,t2017


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Obstentrics_Williams. Schmitz T, Prunet C, Azria E, et aI: Association between planned cesarean delivery and neonatal mortality and morbidity in twin pregnancies. Obstet GynecoIt129(6):986,t2017 Sebire NJ, Foskett M, Paradinas FJ, et al: Outcome of twin pregnancies with complete hydatidiform mole and healthy co-twin. Lancet 359:2165,t2002 Senat MV, Deprest J, Boulvain M, et al: Endoscopic laser surgery versus serial amnioreduction for severe twin-to-twin transfusion syndrome. N Engl J Med 351: 136, 2004 Senat MV, Porcher R, Winer N, et al: Prevention of preterm delivery by 17a1pha-hydroxyprogesterone caproate in asymptomatic twin pregnancies with a short cervix: a randomized controlled trial. Am J Obstet Gynecol 208(3):194.e1,t2013 Shen 0, Samuelof A, Beller U, et I: Number of yolk sacs does not predict amnionicity in early first-trimester monochorionic multiple gestations. Ultrasound Obstet Gynecol 27(1):53, 2006


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Obstentrics_Williams. Shen 0, Samuelof A, Beller U, et I: Number of yolk sacs does not predict amnionicity in early first-trimester monochorionic multiple gestations. Ultrasound Obstet Gynecol 27(1):53, 2006 Shub A, Walker SP: Planned early delivery versus expectant management of monoamniotic twins. Cochran Database Syst Rev 4:CD008820, 2015 Simpson LL: Ultrasound in twins: dichorionic and monochorionic. Semin PerinatoIt37(5):348,t2013 Slaghekke F, Kist ], Oepkes D, et al: Twin anemia-polycythemia sequence: diagnostic criteria, classiication, perinatal management and outcome. Fetal Diagn Ther 27(4):181,t2010 Smith Gc, Fleming M, White IR: Birth order of twins and risk of perinatal death related to delivety in England, Northern Ireland, and Wales, 19942003: retrospective cohort study. BMJ 334(7593):576, 2007


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Obstentrics_Williams. Society for Maternl-Fetal Medicine, Simpson LL: Twin-twin transusion syndrome. Am J Obstet Gynecol 208(1):3, 2013 Sparks TN, Norton ME, Flessel M, et aI: Observed rate of Down syndrome in twin pregnancies. Obstet GynecoIt128(5):1127, 2016 Spencer R: Parasitic conjoined twins: externl, internal (fetuses in fetu and teratomas), and detached (acardiacs). Clin Anat 14:428,2001 Spencer R: Theoretical and analytical embryology of conjoined twins: part I: embryogenesis. Clin Anat 13:36, 2000 Sperling L, Kiil C, Larsen LU, et I: Naturlly conceived twins with monochorionic placentation have the highest risk of fetal loss. Ultrasound Obstet Gynecol 28:644, 2006 Spitz L: Seminars in pediatric surgery: The management of conjoined twins: the great Ormond Street experience. Preface. Semin Pediatr Surg 24(5):201, 2015


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Obstentrics_Williams. Spitz L: Seminars in pediatric surgery: The management of conjoined twins: the great Ormond Street experience. Preface. Semin Pediatr Surg 24(5):201, 2015 Stein W, Misselwitz B, Schmidt 5: Twin-to-twin delivery time interval: influencing factors and efect on short term outcome of the second twin. Acta Obstet Gynecol Scand 87(3):346, 2008 Strandskov HH, Edelen EW, Siemens GJ: Analysis of the sex ratios among single and plural births in the total white and colored U.S. populations. m J Phys Anthropol 4:491, 1946 Sugibayashi R, Ozawa K, Sumie M: et aI: Forty cases of twin reversed arterial perfusion sequence treated with radio frequency ablation using the multistep coagulation method: a single-center experience. Prenat Diagn 36(5):437, 2016 Sunderam 5, Kissin DM, Crawford SB, et al: Assisted reproductive technology surveillance-United States, 2014. MMWR 66(6):1,t2017


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Obstentrics_Williams. Sunderam 5, Kissin DM, Crawford SB, et al: Assisted reproductive technology surveillance-United States, 2014. MMWR 66(6):1,t2017 Szymusik I, Kosinska-Kaczynska K, Bomba-Opon D, et al: IVG versus spontaneous twin pregnancies-which are at higher risk of complications? J Matern Fetal Neonatal Med 25(12):2725,t2012 Talauliker VS, Arulkumaran 5: Reproductive outcomes after assisted conception. Obstet Gynecol Surv 67(9):566, 2012 Tan L, Goon SM, Salmon Y, et I: Conjoined twins. Acta Obstet Gynecol Scand 50:373, 1971 Tannuri A, Batatinha J, Velhote M, et aI: Conjoined twins-twenty years' experience at a reference center in Brazil. Clinics 68(3):371, 2013


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Obstentrics_Williams. Tannuri A, Batatinha J, Velhote M, et aI: Conjoined twins-twenty years' experience at a reference center in Brazil. Clinics 68(3):371, 2013 Taylor M, Rebarber A, Saltzman DH, et aI: Induction of labor in twin compared with singleton pregnancies. Obstet Gynecol 120(2):297,t2012 horngren-Jerneck K, Herbst A: Low 5-minute Apgar score: a populationbased register study of 1 million term births. Obstet GynecoI98(1):65, 2001 horson HL, Ramaeker DM, Emery ST: Optimal interval for ultrasound surveillance in monochorionic twin gestations. Obstet Gynecol 117(1):131, 2011 To MS, Fonseca EB, Molina FS, et al: Maternal characteristics and cervical length in the prediction of spontaneous early preterm delivery in twins. m J Obstet GynecoIt194(5):1360, 2006 Trivedi N, GillettR: he retained twinltriplet following a preterm deliveryan analysis of the literature. Aust N Z J Obstet GynaecoI38:461, 1998


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Obstentrics_Williams. Trivedi N, GillettR: he retained twinltriplet following a preterm deliveryan analysis of the literature. Aust N Z J Obstet GynaecoI38:461, 1998 Turpin R, Lejeune J, Lafourcade J, et I: Presumption of monozygotism in spite of sexul dimorphism: Y male subject and haploid X neuter subject. C R Hebd Seances Acad Sci 252:2945, 1961 Varner MW, Leindecker S, Spong CY, et al: he Maternal-Fetal Medicine Unit Cesarean Registry: trial of labor with a twin gestation. mJ Obstet Gynecol 193:135,t2005 Vintzileos AM, Ananth CV, Kontopoulos E, et al: Mode of delivety and risk of stillbirth and infant mortality in triplet gestations: United States, 1995 through 1998. m J Obstet Gynecol 192:464,t2005 Vora NL, Ruthazer R, House M, et al: Triplet ultrasound growth parameters. Obstet GynecoIt107:694, 2006 Wada H, Nunogami K, Wada T, et aI: Difuse brain damage caused by acute twin-twin transfusion during late pregnancy. Acta Paediatr Jpn 40:370, 1998


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Obstentrics_Williams. Obstet GynecoIt107:694, 2006 Wada H, Nunogami K, Wada T, et aI: Difuse brain damage caused by acute twin-twin transfusion during late pregnancy. Acta Paediatr Jpn 40:370, 1998 Walker MC, Murphy E, Pan 5, et I: Adverse maternal outcomes in multifetal pregnancies. BJOG Ill:1294, 2004 Waller DK, Tita TN, Annegers JF: Rates of twinning before and ater fortiication of foods in the U.S. with folic acid, Texas, 1996 to 1998. Paediatr Perinat EpidemioIt17(4):378, 2003 Wen SW, Demissie K, Yang , et al: Maternal morbidity and obstetric complications in triplet pregnancies and quadruplet and higher-order multiple pregnancies. mJ Obstet Gynecol 191 :254, 2004 White C, Wyshak G: Inheritance in human dizygotic twinning. N Engl J Med 271:1003, 1964 Wolfe MD, de la Torre L, Moore LE, et al: Is the protocol for induction of labor in singletons applicable to twin gestations? J Reprod Med 58(304): 137, 2013


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Obstentrics_Williams. Wolfe MD, de la Torre L, Moore LE, et al: Is the protocol for induction of labor in singletons applicable to twin gestations? J Reprod Med 58(304): 137, 2013 Yamasmit W, Chaithongwongwatthana 5, Tolosa JE, et al: Prophylactic oral betamimetics for reducing preterm birth in women with a twin pregnancy. Cochrane Database Syst Rev 12:CD004733, 2015 Yang Q, Wen SW, Chen Y, et al: Occurrence and clinical predictors of operative delivery for the vertex second twin after normal vaginal delivery of the irst twin. Am J Obstet Gynecol 192(1): 178, 2005a Yang Q, Wen SW, Chen Y, et al: Neonatal death and morbidity in vertexnonvertex second twins according to mode of delivery and birth weight. Am J Obstet GynecoIt192(3):840, 2005b Yeomans ER: Delivery of twin gestations. In Yeomans ER, Hofman BL, Gilstrap LC III, et al (eds): Cunningham and Gilstrap's Operative Obstetrics, 3rd ed. New York, McGraw-Hill Education, 2017


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Obstentrics_Williams. Yeomans ER: Delivery of twin gestations. In Yeomans ER, Hofman BL, Gilstrap LC III, et al (eds): Cunningham and Gilstrap's Operative Obstetrics, 3rd ed. New York, McGraw-Hill Education, 2017 Yinon Y, Mazkereth R, Rosentzweig N, et l: Growth restriction as a determinant of outcome in preterm discordant twins. Obstet Gynecol 105(1):80,t2005 Young BC, Wylie BJ: Efects of twin gestation on maternal morbidity. Semin Perinatol 36(3):162, 2012 Zech NH, Wisser J, Natalucci G, et al: Monochorionic-diamniotic twins discordant in gender form a naturally conceived pregnancy through postzygotic sex chromosome loss in a Y zygote. Prenat Diagn 28:759, 2008 Zhao DP, de Villiers SF, Slaghekke F, et al: Prevalence, size, number and localization of vascular anastomoses in monochorionic placentas. Placenta 34:589,t2013


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Obstentrics_Williams. Y zygote. Prenat Diagn 28:759, 2008 Zhao DP, de Villiers SF, Slaghekke F, et al: Prevalence, size, number and localization of vascular anastomoses in monochorionic placentas. Placenta 34:589,t2013 Zwijnenburg PJ, Meijiers-Heijboer H, Boomsma DI: Identical but not the same: the value of discordant monozygotic twins in genetic research. Am J Med Genet B Neuropsychiatr Genet 153B(6):1134, 2010 MEDICATIONS AND SURGERIES ................... 901 LAPAROSCOPIC SURGERY ....................... 901 RADIOGRAPHY ................................. 904 DIAGNOSTIC RADIATION . . . . . . . . . . . . . . . . . . . . . . . . 906 SONOGRAPHY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 909 MAGNETIC RESONANCE IMAGING ................. 909 As a rule, al diseases which subject the organism to a considerable strain are much more serious when occurring in a pregnant woman. -J. Whitridge Williams (1903)


Obstentrics_Williams

Obstentrics_Williams. As a rule, al diseases which subject the organism to a considerable strain are much more serious when occurring in a pregnant woman. -J. Whitridge Williams (1903) As reviewed by Williams in 1903, pregnant women are susceptible to any medical and surgical disorder that can afect childbearing-aged women. Some of these, especially those that are chronic, more often precede pregnancy. But, they can acutely complicate an otherwise normal pregnancy. Of estimates, one managed-care population had an overall antenatal hospitalization rate of 10.1 per 100 deliveries (Gazmararian, 2002). Approximately one third was for nonobstetrical conditions that included renal, pulmonary, and infectious diseases. In another study from the 2002 Nationwide Inpatient Sample, the injury hospitalization rate was 4.1 women per 1000 deliveries (Kuo, 2007). Last, approximately 1 in every 635 pregnant women will undergo a nonobstetrical surgical procedure (Corneille, 2010; Kizer, 2011).


Obstentrics_Williams

Obstentrics_Williams. Obstetricians should have a working knowledge of the wide-ranging medical disorders common to childbearing-aged women. Many of these are within the purview of the general obstetrician. Other disorders, however, will warrant consultation, and still others require a multidisciplinary team. The latter may include maternal-fetal medicine specialists, hospitalists, internists and medical subspecialists, surgeons, anesthesiologists, and numerous other disciplines (Levine, 2016). The American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine (2014, 2017b) has redefined aspects of maternal care and proposed required levels of specialized care. It should be axiomatic that a woman must never be penalized because she is pregnant. To ensure this, several questions should be addressed: What management would be recommended if the woman were not pregnant? If the proposed management is diferent because the woman is pregnant, can this be justiied?


Obstentrics_Williams

Obstentrics_Williams. What management would be recommended if the woman were not pregnant? If the proposed management is diferent because the woman is pregnant, can this be justiied? What are the risks versus benefits to the mother and her fetus, and are they counter to each other? Can an individualized management plan be devised that balances beneits versus risks of any alterations? Such an approach allows individualized care for women with most medical and surgical disorders complicating pregnancy.


Obstentrics_Williams

Obstentrics_Williams. Such an approach allows individualized care for women with most medical and surgical disorders complicating pregnancy. Pregnancy induces physiological changes in virtually all organ systems. In turn, results of numerous laboratory tests are altered, and some values would, in the nonpregnant woman, be considered abnorml. Conversely, some may appear to be within a normal range but are decidedly abnormal for the gravida. These changes may ampliy or obuscate evaluation of coexisting conditions. he wide range of pregnany efects on normal physiology and laboratory values are discussed in the chapters that follow in this section and are listed in the Appendix (p. 1255). Fortunately, most medications needed to treat frequently with relative safety. That said, notable exceptions are considered in Chapter 12 and throughout this text.


Obstentrics_Williams

Obstentrics_Williams. Fortunately, most medications needed to treat frequently with relative safety. That said, notable exceptions are considered in Chapter 12 and throughout this text. Regarding surgery, the risk of an adverse pregnancy out come is not appreciably increased in most women who undergo an uncomplicated operative procedure. With complications, however, risks likely are increased. For example, perforative appendicitis with feculent peritonitis has significant maternal and anesthetic techniques are flawless. Conversely, procedure related complications may adversely afect outcomes. For exam ple, a woman who has uncomplicated removal of an inflamed appendix may sufer aspiration of acidic gastric contents dur ing tracheal intubation or extubation. Still, compared with nonpregnant women undergoing similar procedures, pregnant women do not appear to have excessive complications (Silvestri, 2011). In a study of the American College of Surgeons'


Obstentrics_Williams

Obstentrics_Williams. National Surgical Quality Improvement Program, outcomes in pregnant women were compared with matched nonpregnant controls (Moore, 2015). The investigators reported similar out comes in the two cohorts, each with 2539 patients. In a smaller study, however, women undergoing nonobstetrical surgery after 23 weeks' gestation had a high rate of subsequent preterm delivery (Baldwin, 2015).


Obstentrics_Williams

Obstentrics_Williams. The most extensive data regarding anesthetic and surgical risks for the gravida and her fetus are from the Swedish Birth and described by Mazze and Kallen (1989). The efects on pregnancy outcomes of 5405 nonobstetrical surgical procedures performed in 720,000 pregnant women from 1973 to 1981 were analyzed. For approximately half of these procedures, general anesthesia was used and commonly involved nitrous oxide supplemented by another inhalation agent or intravenous medications. These procedures were performed in 41 percent of women in the first trimester, 35 percent in the second, and 24 percent in the third. Overall, 25 percent were abdominal operations, and 20 percent were gynecological or urological procedures. Laparoscopy was the most frequently performed operation, and appendectomy was the most common second-trimester procedure.


Obstentrics_Williams

Obstentrics_Williams. Excessive perinatal morbidity associated with nonobstetrical surgery is attributable in many cases to the disease itself rather than to adverse efects of surgery and anesthesia. he Swedish Birth Registry again provides valuable data (Table Importantly, the incidences of congenital malformations or of stillbirths were not significantly diferent from those of nonexposed control newborns. However, incidences of low birthweight, preterm birth, and neonatal death in infants born to women who had undergone surgery were significantly greater. TABLE 46-1. Birth Outcomes in 5405 Pregnant Women Undergoing Nonobstetrical Surgery Major malformation 1.9% NS Stillbirth 7 per 1000 NS Neonatal death by 7 days 10.5 per 1 000 <0.05 Preterm <37 wk 7.5% <0.05 Birthweight < 1500 g 1.2% <0.05 Birthweight <2500 g 6.6% <0.05 aCompared with 720,000 pregnancies in women without surgery. NS = not significant. Data from Mazze, 1989.


Obstentrics_Williams

Obstentrics_Williams. Preterm <37 wk 7.5% <0.05 Birthweight < 1500 g 1.2% <0.05 Birthweight <2500 g 6.6% <0.05 aCompared with 720,000 pregnancies in women without surgery. NS = not significant. Data from Mazze, 1989. Increased neonatal death rates were largely due to preterm birth. In two other studies, the preterm delivery rate in women undergoing nonobstetrical surgery was also elevated (Baldwin, 2015; Hong, 2006). Rates of fetal abnormalities with maternal surgery in early pregnancy do not appear increased. Kallen and Mazze (1990) scrutinized 572 operations performed at 4 to 5 weeks' gestation and reported a nonsignificant relationship with elevated neural-tube defect rates. In a similar study from a Hungarian database, Czeizel and colleagues (1998) found no evidence that anesthetic agents were teratogenic.


Obstentrics_Williams

Obstentrics_Williams. Laparoscopy has become the most common first-trimester procedure used for diagnosis and management of several surgical disorders. In 2017, the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) updated its recommendations concerning laparoscopy use in pregnant women (Table 46-2).


Obstentrics_Williams

Obstentrics_Williams. Information regarding surgical approach selection in pregnancy comes from the American College of Surgeons database (Silvestri, 2011). During the 5-year period ending in 2009, almost 1300 pregnant women were studied who had undergone either appendectomy or cholecystectomy. Open appendectomy was performed in 36 percent of 857 gravidas compared with only 17 percent of those not pregnant. Of those undergoing cholecystectomy, an open procedure was used in 10 percent of 436 pregnant women compared with 5 percent of nonpregnant women. No randomized trials compare laparoscopic with open surgery, however, most reviews report equally satisfactory outcomes (Bunyavejchevin, 2013; Cox, 2015; Fatum, 2001). The most frequently performed procedures were cholecystectomy, adnexal surgery, and appendectomy. For adnexal mass surgery in pregnancy, laparoscopy is preferred, and several studies conirm its relative safety (Daykan, 2016; Hoover, 2011; Webb, 2015). At first, 26 to 28 weeks became the upper


Obstentrics_Williams

Obstentrics_Williams. For adnexal mass surgery in pregnancy, laparoscopy is preferred, and several studies conirm its relative safety (Daykan, 2016; Hoover, 2011; Webb, 2015). At first, 26 to 28 weeks became the upper gestational-age limit recommended, but as experience has accrued, many now describe laparoscopic surgery performed in the third trimester (Kizer, 2011). In one report of 59 gravidas undergoing laparoscopic cholecystectomy or appendectomy, a third were > 26 weeks'


Obstentrics_Williams

Obstentrics_Williams. TABLE 46-2. Some Guidelines from the Society of American Gastrointestinal Endoscopic Surgeons (SAGES) for Laparoscopic Surgery in Pregnant Women Indications-same as for nonpregnant women Investigation of acute abdominal processes Appendectomy, cholecystectomy, nephrectomy, adrenalectomy, splenectomy Position: lateral recumbent Entry: open technique, careful Veress needle, or optical trocar; fundal height may alter insertion site selection Trocars: direct visualization for placement; fundal height may alter insertion site selection CO2 insuflation pressures: 10-15 mm Hg Monitoring: capnography intraoperatively, FHR assessment pre-and postoperatively Perioperative pneumatic compression devices and early postoperative ambulation CO2 = carbon dioxide; FHR = fetal heart rate. Data from Pearl, 2017.


Obstentrics_Williams

Obstentrics_Williams. CO2 = carbon dioxide; FHR = fetal heart rate. Data from Pearl, 2017. gestation (Rollins, 2004). No serious adverse sequelae are In women, cardiorespiratory changes are generally not linked to these procedures. In addition, laparoscopic splesevere if insulation pressures are kept below 15 mm Hg. With nectomy, adrenalectomy, and nephrectomy have also been noninvasive hemodynamic monitoring in women at midpregdescribed in pregnant women (Asizare, 2014; Dong, 2014; nancy, the cardiac index decreased 26 percent by 5 minutes of Gernsheimer, 2007; Miller, 2012; Stroup, 2007). insulation and 21 percent by 15 minutes (Steinbrook, 2001). Despite this, mean arterial pressures, systemic vascular resistance, and heart rate did not change significantly.


Obstentrics_Williams

Obstentrics_Williams. Despite this, mean arterial pressures, systemic vascular resistance, and heart rate did not change significantly. changes that are summarized in Table 46-3. Reedy and associ ates (1995) studied baboons at the human equivalent of 22 to Laparoscopic surgery frequently is ideal for the obese woman 26 weeks' gestation. No substantive physiological changes were (Sisodia, 2015). However, some outcomes may be adversely found with insulation pressures of 10 mm Hg, but 20 mm afected in obese gravidas compared with normal-weight


Obstentrics_Williams

Obstentrics_Williams. Hg caused significant maternal cardiovascular and respiratory patients. Of these, higher conversion rates to laparotomy, changes after 20 minutes. hese included increased respiratory longer operating times, and longer hospitalizations have rate, respiratory acidosis, diminished cardiac output, and been reported. Also, adequate ventilation is more diicult, increased pulmonary artery and capillary wedge pressures. and greater pneumoperitoneal pressures are needed to create aEffects intensified when insufflation pressure >20 mm Hg in baboons (Reedy, 1995). bData primarily from animal studies. CO2 =carbon dioxide; CSF = cerebrospinal fluid; PC02 = patial pressure of CO2, Data from O'Rourke, 2006; Reynolds, 2003. suitable operating space. here is anatomical distortion of the abdominal wall with displaced landmarks. Finally, the risk of developing hernias at port sites is greater.


Obstentrics_Williams

Obstentrics_Williams. suitable operating space. here is anatomical distortion of the abdominal wall with displaced landmarks. Finally, the risk of developing hernias at port sites is greater. Because precise efects of laparoscopy in the human fetus are unknown, animal studies are informative. In early studies of pregnant ewes, various investigators reported that uteroplacental blood low declines when intraperitoneal insulation pressure exceeded 15 mm Hg (Barnard, 1995; Hunter, 1995). This was the result of decreased perfusion pressure and increased placental vessel resistance (see Table 46-3). The previously cited baboon studies by Reedy and coworkers (1995) produced similar findings.


Obstentrics_Williams

Obstentrics_Williams. Perinatal outcomes in women are limited to observational studies. Reedy and colleagues (1997) used the updated Swedish Birth Registry database to analyze a 20-year period with more than 2 million deliveries. Of 2181 laparoscopic procedures, most were performed during the irst trimester. Perinatal outcomes for these women were compared with those of all women in the database and those undergoing open surgical procedures. These investigators confirmed the earlier indings of an increased risk of low birthweight, preterm delivery, and fetal-growth restriction. Diferences were not found, however, in outcomes of women undergoing laparoscopy versus laparotomy. n observational study of 262 women undergoing surgery for an adnexal mass noted similar findings (Koo, 2012). The following description is an overview of laparoscopic techniques in pregnancy. For a detailed description refer to Chapter 15 in Cunningham and Gistrap s Operative Obstetrics, 3rd edition (Kho, 2016).


Obstentrics_Williams

Obstentrics_Williams. Preparation for laparoscopy difers little from that used for laparotomy. Bowel cleansing is not needed but may aid visualization and manipulations by emptying the large intestine. N asogastric or orogastric decompression reduces the risk of stomach trocar puncture and aspiration. Aortocaval compression is avoided by a left-lateral tilt. Positioning of the lower extremities in boot-type stirrups maintains access to the vagina for fetal sonographic assessment or manual uterine displacement. Intrauterine manipulators are logically avoided. Most reports describe the use of general anesthesia after tracheal intubation with monitoring of end-tidal carbon dioxideEtC02 (Hong, 2006; Ribic-Pucelj, 2007). With controlled ventilation, EtC02 is maintained at 30 to 35 mm Hg.


Obstentrics_Williams

Obstentrics_Williams. Beyond the irst trimester, technical modifications of standard pelvic laparoscopic entry are required to avoid uterine puncture or laceration (Fig. 46-1). Many recommend open enuy techniques to avoid perforations of the uterus, pelvic vessels, and adnexa (Kizer, 2011; Koo, 2012). The abdomen is incised at or above the umbilicus, and the peritoneal cavity entered under direct visualization (Fig. 46-2). At this point, the cannula is then connected to the insulation system, and a 12-mm Hg pneumoperitoneum is created. The initial insulation should be conducted slowly to allow for prompt assessment and reversal of any untoward pressure-related efects. Gas leakage around the cannula is managed by tightening the surrounding skin with a towel clamp. Insertion of secondary trocars into the abdomen is most safely performed under direct laparoscopic viewing. Single-port surgery has also been described (Dursun, 20l3).


Obstentrics_Williams

Obstentrics_Williams. In more advanced pregnancies, direct entry through a left upper quadrant port in the midclavicular line, 2 cm beneath the costal margin, may better avoid the fundus (Donkervoort, 2011; Stepp, 2004). Known as Palmer point, this entry site is also used in gynecological laparoscopy because visceroparietal adhesions infrequently form here (Vilos, 2007). FIGURE 46-1 Pregnant uterus at 10,o20, and 36 weeks' gestation depicting distortion of other intraperitoneal organs. (Reproduced with permission from Kho KA: Diagnostic and operative laparoscopy. In Yeomans ER, Hoffman BL, Gilstrap LC III, et al (eds): Cunningham and Gilstrap's Operative Obstetrics 3rd ed, New York McGraw-Hili Education, 201o7.)


Obstentrics_Williams

Obstentrics_Williams. FIGURE 46-2 Open entry technique for laparoscopic instrument placement. A. Fascia grasped with two Allis clamps and elevated prior to sharp incision. B.Two fascial stitches incorporate the peritoneum and fascia. C. These fascial sutures are wrapped around holders of the Hasson cannula to anchor it in place. (Reproduced with permission from Kho KA: Diagnostic and operative laparoscopy. In Yeomans ER, Hoffman BL, Gilstrap LC III, et al (eds): Cunningham and Gilstrap's Operative Obstetrics 3rd ed, New York McGraw-Hili Education, 201o7.) Gasless laparoscopy is a less commonly selected alternative approach that uses a rod with intraabdominal fan-blade-shaped retractors. When opened, these allow the abdominal wall to be lifted upward. It avoids the typical laparoscopic cardiovascular changes because the pneumoperitoneum is created by retraction rather than insuiation (Phupong, 2007).


Obstentrics_Williams

Obstentrics_Williams. Risks inherent to any abdominal endoscopic procedure are probably increased slightly during pregnancy. The obvious unique complication is perforation of the pregnant uterus with either a trocar or Veress needle (Azevedo, 2009; Kizer, 2011; Mala, 2014). hat said, reported complications are infrequent (Fatum, 2001; Koo, 2012). One Cochrane database review noted a need for randomized trials to deduce comparative benefits and risks of laparoscopy versus laparotomy during pregnancy (Bunyavejchevin, 2013). Pragmatically, this seems unfeasible, and common sense should dictate the approach.


Obstentrics_Williams

Obstentrics_Williams. Imaging modalities are used as adjuncts for diagnosis and therapy during pregnancy. Options include sonography, radiography, and magnetic resonance (MR) imaging. Of these, radiography is the most problematic. Inevitably, some radiographic procedures are performed before recognition of early pregnancy, usually because of trauma or serious illness. Fortunately, most diagnostic radiographic procedures are associated with minimal fetal risks. As with drugs and medications, however, these procedures may lead to litigation if pregnancy outcome is adverse. And, x-ray exposure may lead to a needless therapeutic abortion because of patient or physician anxiety.


Obstentrics_Williams

Obstentrics_Williams. Since 2007, the American College of Radiology (ACR) has addressed the growing concern of radiation dose in all ields of medicine (Amis, 2007). Some of its goals were to limit exposure through radiation safety practices and promote lifelong accumulated records of exposures in any given patient. Task Force recommendations included additional considerations for special radiosensitive populations, such as children and pregnant and potentially pregnant women. At our institutions, special recommendations are made for gravidas. Radiation exposure values and duration are recorded and monitored in high-exposure areas such as computed tomography (CT) and luoroscopy.


Obstentrics_Williams

Obstentrics_Williams. he term radiation literally refers to energy transmission and thus is often applied not only to x-rays, but also to microwaves, ultrasound, diathermy, and radio waves. Of these, x-rays and gamma rays have short wavelengths with very high energy and are ionizing radiation forms. The other four energy forms have rather long wavelengths and low energy (Brent, 1999b, 2009). Ionizing radiation refers to waves or particles-photons-of signiicant energy that can change the structure of molecules such as those in DNA or that can create free radical or ions capable of secondarily damaging tissue (Hall, 1991; National Research Council, 1990). Methods of measuring the efects of x-rays are summarized in Table 46-4. The standard terms used are exposure TABLE 46-4. Some Measures of Ionizing Radiation Exposure Number of ions produced by x-rays per kg Dose Amount of energy deposited per kg of tissue


Obstentrics_Williams

Obstentrics_Williams. TABLE 46-4. Some Measures of Ionizing Radiation Exposure Number of ions produced by x-rays per kg Dose Amount of energy deposited per kg of tissue Relative Amount of energy deposited per kg effective of tissue normalized for biological (in air), dose (to tissue), and reative fictive dose (to tissue). In the range of energies for diagnostic x-rays, the dose is now expressed in grays (Gy) , and the relative efective dose is expressed in sieverts (Sv). hese can be used interchangeably. For consistency, all doses discussed subsequently are expressed in contemporane ously used units of gray (1 Gy = 100 rad) or sievert (1 Sv = 100 rem) . To convert, 1 Sv = 100 rem = 100 rad. As noted, the biological efects of x-rays are caused by an electrochemical reaction that can damage tissue. According to


Obstentrics_Williams

Obstentrics_Williams. As noted, the biological efects of x-rays are caused by an electrochemical reaction that can damage tissue. According to Brent (1999a, 2009), x-and gamma-radiation at high doses can create two types of biological efects and reproductive risks in the fetus. These are deterministic eicts and stochastic focts, which are both described in the next sections. One potential harmful efect of radiation exposure is determin istic, which may result in abortion, growth restriction, congeni tal malformations, microcephaly, or mental retardation. hese deterministic efects are threshold efects, and the threshold level is the NOAEL-No Observed Adverse Eict Level (Brent, 2009). lthough controversial, the NOEL concept supports that there is no risk below a threshold dose (0.05 Gy or 5 rad). It also suggests that the threshold for gross fetal malformations is more likely to be 0.2 Gy (20 rad).


Obstentrics_Williams

Obstentrics_Williams. It also suggests that the threshold for gross fetal malformations is more likely to be 0.2 Gy (20 rad). The harmful deterministic efects of ionizing radiation have been extensively studied for cell damage with resultant disordered embryogenesis. These have been assessed in animal models, as well as in Japanese atomic bomb survivors and the Oxford Survey of Childhood Cancers (Sorahan, 1995). Additional sources have confirmed prior observations and provided more information (Groen, 2012). One is a 2003 International Commission on Radiological Protection publication that describes biological fetal efects from prenatal irradiation. Another is the Biological Efects of Ionizing Radiation-BEIR II Phase 2 report of the National Research Council (2006), which discusses health risks from exposure to low levels of ionizing radiation.


Obstentrics_Williams

Obstentrics_Williams. In the mouse model, the lethality risk is highest during the preimplantation period-up to 10 days postconception (Kanter, 2014). This is likely due to blastomere destruction caused by chromosomal damage (Hall, 1991). During organogenesis, high-dose radiation-1 Gy or 100 rad-is more likely to cause malformations and growth restriction and less likely to have lethal efects in the mouse. Studies of brain development suggest efects on neuronal development and a window of cortical sensitivity in early and midfetal periods. That said, acute lowdose ionizing radiation appears to have no deleterious efects (Howell,r2013). Data on adverse human efects of high-dose ionizing radiation mostly derive from the atomic bomb survivors of Hiroshima and Nagasaki (Greskovich, 2000; Otake, 1987). The International Commission on Radiological Protection (2003) confirmed initial studies showing that the increased risk of severe mental retardation was greatest between 8 and 15 weeks' gestation.