Selective feticide in monochorionic twin pregnancies by ultrasound-guided umbilical cord occlusion

Outcome of Monochorionic Pregnancies after Selective Feticide with Bipolar Cord Coagulation: A German Single Center Experience

Objectives: To review the outcome of complicated monochorionic pregnancies after fetoscopic selective feticide with bipolar cord coagulation in an experienced German center. Methods: All cases that underwent selective feticide using fetoscopic bipolar umbilical cord occlusion (and simultaneous dissection in monoamniotics) at the University of Bonn in the past 10 years were retrospectively analyzed for antenatal and neonatal course and outcome. An adverse outcome was defined as either intrauterine death (IUD), neonatal death (NND), preterm prelabour rupture of membranes (PPROM), or preterm delivery (PTD) before 32.0 weeks of gestation. Results: We diagnosed 56 monochorionic pregnancies, including 43 diamniotic and 8 monoamniotic twins, as well as 5 triplets, complicated by discordant fetal anomalies (n = 10), selective intrauterine growth restriction (n = 29), twin-to-twin transfusion syndrome (n = 13), twin reversed arterial perfusion sequence (n = 3), or severe early twin anemia polycythemia sequence (n = 1), that underwent fetoscopic selective feticide in the 10 years study period. Selective feticide was performed by bipolar cord coagulation at a median gestational age of 21.2 weeks. PPROM occurred in 11 cases, 7 (12.5%) before 32.0 weeks and 4 (7.1%) between 34.0 and 36.0 weeks, respectively. There were five (8.9%) co-twins IUDs at a median of 2 weeks after the intervention. We observed 12 (21.4%) PTDs before 32.0 weeks of gestation and 2 (3.6%) NNDs. Mean gestational age at delivery was 37.1 weeks, with an overall survival of the co-twin of 87.5%. Conclusion: In experienced hands, fetoscopic selective feticide is an effective treatment in complicated monochorionic pregnancies. By sacrificing a sick fetus that jeopardizes the entire pregnancy, a higher survival rate of the co-twin can be achieved.

Perinatal outcomes after selective feticide via umbilical cord occlusion in complicated monochorionic pregnancies: A systematic review and meta-analysis

OBJECTIVE

We aimed to compare perinatal outcomes between umbilical cord occlusion techniques in monochorionic pregnancies, including umbilical cord ligation, fetoscopic laser coagulation, interstitial laser coagulation, bipolar cord occlusion, radiofrequency ablation, and microwave ablation.

METHODS

This study was registered with PROSPERO (CRD42020158861). PubMed, Web of Science, Cochrane Library, and Embase were searched for studies published up to May 2020. The DerSimonian-Laird random-effects model was used for the meta-analysis. Subgroup analyses were performed to compare the outcomes among the six techniques. Meta-regression was used to adjust for confounders.

RESULTS

Thirty-four studies with 1646 participants were included. The overall survival was 76.5% after umbilical cord ligation, 78.8% after fetoscopic laser coagulation, 60.3% after interstitial laser coagulation, 79.2% after bipolar cord occlusion, 77.5% after radiofrequency ablation, and 75.0% after microwave ablation. Subgroup comparison showed the rates of overall survival and preterm premature rupture of membranes were not significant different among six techniques. However, rates of fetal loss, premature birth, live birth, and neonatal death differed significantly among the six groups.

CONCLUSIONS

The choice of umbilical cord occlusion techniques will affect perinatal outcomes. We suggested that the choice of umbilical cord occlusion techniques should fully consider these differences among techniques.

Severe fetal anemia after umbilical cord occlusion leading to severe neurological injury in monochorionic twins

We describe two cases of monochorionic twins with severe anemia in the surviving twin after cord occlusion. The first one was a case of discordant malformation (anencephalia) and the second one was a case of early severe selective intrauterine growth restriction type II in a dichorionic triamniotic triplet pregnancy. In both cases, the cord of the occluded fetus had a marginal insertion. Both of them presented hydrops 2 d after the occlusion, having measurements of the peak systolic velocity (PSV) of the middle cerebral artery (MCA) above 1.5 multiples of the median (MoM). In the first one intrauterine transfusion was performed with pretransfusion measurement of fetal hemoglobin of 3.3 g/dL. An extensive area of destruction of brain tissue at the right parietal-temporal-occipital level was diagnosed at 300 weeks. In the second one, expectant management was decided and a grade 3 intraventricular hemorrhage associated with moderate ventriculomegaly was detected at 22 weeks' gestation. We hypothesize that the surviving fetus after the occlusion can become bloodless and hypovolemic when its blood is poured into the placental and umbilical circulation of the occluded twin through the vascular anastomoses between them. It should not be assumed that cord occlusion removes the risk of transfusional brain injury in surviving-cotwins.

Maternal complications following open and fetoscopic fetal surgery: A systematic review and meta-analysis

OBJECTIVE

To establish maternal complication rates for fetoscopic or open fetal surgery.

METHODS

We conducted a systematic literature review for studies of fetoscopic or open fetal surgery performed since 1990, recording maternal complications during fetal surgery, the remainder of pregnancy, delivery, and after the index pregnancy.

RESULTS

One hundred sixty-six studies were included, reporting outcomes for open fetal (n = 1193 patients) and fetoscopic surgery (n = 9403 patients). No maternal deaths were reported. The risk of any maternal complication in the index pregnancy was 20.9% (95%CI, 15.22-27.13) for open fetal and 6.2% (95%CI, 4.93-7.49) for fetoscopic surgery. For severe maternal complications (grades III to V Clavien-Dindo classification of surgical complications), the risk was 4.5% (95% CI 3.24-5.98) for open fetal and 1.7% (95% CI, 1.19-2.20) for fetoscopic surgery. In subsequent pregnancies, open fetal surgery increased the risk of preterm birth but not uterine dehiscence or rupture. Nearly one quarter of reviewed studies (n = 175, 23.3%) was excluded for failing to report the presence or absence of maternal complications.

CONCLUSIONS

Maternal complications occur in 6.2% fetoscopic and 20.9% open fetal surgeries, with serious maternal complications in 1.7% fetoscopic and 4.5% open procedures. Reporting of maternal complications is variable. To properly quantify maternal risks, outcomes should be reported consistently across all fetal surgery studies.

Selective reduction in complicated monochorionic twins: prediction of obstetric outcome and comparison of techniques

OBJECTIVES

To compare the outcomes of radiofrequency ablation (RFA) and bipolar cord coagulation (BPC) methods for selective feticide in complicated monochorionic (MC) twin gestations and to determine risk factors for adverse pregnancy outcome.

METHODS

This was a retrospective cohort study of all patients with complicated MC twin pregnancy who underwent selective reduction in a single tertiary care center between 2000 and 2014. We compared the two methods with respect to various demographic, obstetric and perinatal outcome variables.

RESULTS

Fifty-three selective terminations in complicated MC twin gestations were performed, 36 by RFA and 17 by BPC. Each technique resulted in a similar overall survival rate of the remaining twin (88.9% vs 76.5%, P = 0.25). Likewise, the mean procedure-to-delivery interval, the rate of spontaneous preterm delivery < 37, < 34, < 32 and < 28 weeks and the rate of preterm prelabor rupture of the membranes did not differ between the groups. However, among patients in the BPC group, there was a trend towards earlier gestational age at delivery (31.3 vs 35.0 weeks, P = 0.09) compared with in the RFA group. There was selective reduction by RFA due to selective intrauterine growth restriction (sIUGR) in 19 cases, 17 (89.5%) of which survived perinatally, with delivery at a median gestational age of 37 weeks. There were no significant differences in perinatal outcome, irrespective of whether the procedure was performed pre- or post-viability. All post-viability reductions, most of which were by RFA, resulted in perinatal survival.

CONCLUSIONS

Perinatal outcome of complicated MC twin gestations undergoing selective feticide seems to be similar regardless of whether termination is by BPC or RFA. Nevertheless, RFA appears to be particularly useful in MC twins complicated by sIUGR and in cases requiring selective reduction beyond the age of viability.

[Selective termination of pregnancy for monochorionic twins: a national survey of professional practice]

OBJECTIVES

Selective Termination of Pregnancy (STOP) for discordant fetal condition in monochorionic twin pregnancy is a rarely performed procedure raising technical and ethical considerations. There are no epidemiological data available in France concerning STOP and no guideline or scientific consensus on how or when to perform has been published.

MATERIALS AND METHODS

We conducted a study of national practice using a declarative questionnaire sent by e-mail to each medical coordinator of every 48 Multidisciplinary Center for Prenatal Diagnosis in France. The questions focused on the issues of 2010 and 2011. Two reminders were sent in case of no answer.

RESULTS

The response rate to the questionnaire was 56 %; 81 % of centers have experienced at least once during the two years 2010-2011 a discordant fetal anomaly in monochorionic twin pregnancy. Only 59 % of centers perform all the techniques of STOP. When interruption of the umbilical blood flow is considered, bipolar forceps coagulation is the most used (75 %). Achieving STOP during a cesarean section is a common practice (75 % of centers). Locoregional anesthesia is the preferred mode of anesthesia for STOP.

DISCUSSION AND CONCLUSION

STOP on monochorionic twin pregnancy is not practiced in all Multidisciplinary Center for Prenatal Diagnosis in France. The most widely practiced and most studied technique is bipolar forceps coagulation. The option of an expectant management should always be considered and its risks should be balanced with those of STOP. The practice of STOP during cesarean section is not unusual.

[Pediatric outcome after selective feticide for 30 complicated monochorionic twin pregnancies]

OBJECTIVES

To describe perinatal and pediatric outcome after selective feticide for complicated monochorionic twin pregnancy.

PATIENTS AND METHODS

We reviewed all consecutive cases of umbilical cord occlusion performed for complicated monochorionic twin pregnancy over a 16-year period. Pediatric follow-up was based on medical records and updated by phone calls to the parents.

RESULTS

Thirty procedures were performed. Indications were: twin-to-twin transfusion syndrome (TTTS) progressing despite serial amniodrainage (n=12) ; twin reversed arterial perfusion (n=9) ; selective growth restriction (n=5) ; severe discordant structural anomalies (n=4). Mean gestational age at procedure was 21.8±3.1gestational weeks (GW) and 31.8±4.8 GW at birth. Overall survival rate was 87%, i.e. 83%, 100%, 60% and 100% for each indication, respectively. Mean pediatric follow-up was 5years (range: 6months to 15years). Medical charts and parents declared normal development in 88% of surviving children, i.e. 67%, 100%, 100%, and 100% for each indication. Cross-comparison between the four groups revealed that in the TTTS group, gestational age at procedure was more advanced (P=0.01) while delivery was slightly earlier (P=0.1), and pediatric development was poorer (P=0.02).

DISCUSSION AND CONCLUSION

Pediatric outcome after selective feticide appeared to be poorer for TTTS progressing despite serial amniodrainage than for other indications.

Selective reduction and termination of multiple pregnancies

The substantial increase in high order multiple pregnancies in the last two decades as a result of assisted reproductive techniques has necessitated the development of multifetal pregnancy reduction as a management tool to decrease fetal number and improve perinatal survival. The evidence in favour of reduction in pregnancies with more than four fetuses to twins is undisputed. Despite the recent improvements in expectant management of triplets with reasonable perinatal outcomes, the evidence suggests that reduction to twins significantly reduces the risk of preterm delivery without an increase in miscarriage rates. Recent advances in vascular-occlusive techniques have allowed the possibility of selective termination in monochorionic pregnancies in the presence of discordant anomalies or indeed multifetal reduction in non-trichorionic triplets, with radiofrequency ablation and cord occlusion appearing to be the most successful. However, the techniques vary in complexity and complication rates, which increase with gestation. Hence the need to refer these pregnancies early to specialist centres.

Specific complications of monochorionic twin pregnancies: twin-twin transfusion syndrome and twin reversed arterial perfusion sequence

Monochorionic twins are subjected to specific complications which originate in either imbalance or abnormality of the single placenta serving two twins. This unequal placental sharing can cause complications including twin-twin transfusion syndrome (TTTS), twin anemia-polycythemia sequence (TAPS), selective intrauterine growth restriction or twin reversed arterial perfusion sequence (TRAP). Monochorionicity also makes the management of these specific complications as well as that of a severe malformation in one twin hazardous since the spontaneous death of one twin exposes the co-twin to a risk of exsanguination into the dead twin and its placenta. The latter is responsible for the death of the co-twin in up to 20% of the cases and in ischemic sequelae in about the same proportions in the survivors. Although the symptoms of all these complications are very different, the keystone of their management comes down to either surgical destruction of the inter-twin anastomoses on the chorionic plate when aiming at dual survival or selective and permanent occlusion of the cord of a severely affected twin aiming at protecting the normal co-twin. This can be best achieved by fetoscopic selective laser coagulation and bipolar forceps cord coagulation respectively.

Umbilical cord occlusion for selective feticide in complicated monochorionic twins: a systematic review of literature

The aim of this study was to review literature concerning selective feticide (SF) in monochorionic pregnancies complicated with twin-twin transfusion syndrome, twin reversed arterial perfusion, severe malformation, and discordant growth. The remaining twins' outcomes were stratified for indication and surgical technique. Three hundred forty-five cases of SF were reviewed. Premature rupture of membranes was described in all the procedures and complicated 76/345 (22%) pregnancies within 4 postoperative weeks (59%) or later (41%; P = .52). Fetal demise accounted for 51/345 (15%), more frequently within 2 postoperative weeks (79%) than thereafter (21%; P = .004; odds ratio [OR], 6.12; 95% confidence interval [CI], 1.81-20.70). Improved survival rate was achieved in surgeries after 18 weeks (89%) than earlier (69%; P = .02; OR, 0.28; 95% CI, 0.10-0.80) without differences for indication. Survivors were 86% after radiofrequency ablation, 82% after bipolar cord coagulation, 72% after laser cord coagulation, 70% after cord ligation. In spite of favorable outcomes, the optimal surgical approach remains undetermined.

Radiofrequency driven cord occlusion for selective termination of pregnancy: evaluation in the fetal sheep

OBJECTIVE

This study was designed to assess the ability of an ultrasound-guided radiofrequency (RF)-driven procedure to induce complete and irreversible cord occlusion using a 90 days fetal sheep model.

STUDY DESIGN

Twenty 90 days gestation sheep underwent general anesthesia. The first ten fetuses were exposed under hysterotomy, and RF electrode was inserted visually in the middle of the umbilical cord and deployed. Fetuses were then replaced into the amniotic fluid and RF procedure (average target temperature of 100 degrees C during 10 minutes) was applied. For the next ten fetuses, RF electrode was inserted into the cords under trans-parietal ultrasound guidance and the same RF procedure was applied. Cord occlusion was assessed by Doppler examination (absence of cordonal flows at the end of the procedure and until fetal heart failure occurred) and by subsequent histopathological analysis.

RESULTS

Cord occlusion was always complete at Doppler examination at the end of RF procedure for the ten experiments realized under hysterotomy. No cordonal reperfusion was observed until fetal heart failure. Histopathological analysis confirmed cordonal occlusion at the site of impact. Neither cordonal rupture nor cordonal bleeding was observed for any of the ten experiments. When RF electrode was inserted under ultrasound guidance, complete occlusion could be obtained only for 6 of the ten experiments.

CONCLUSION

Our results suggest that RF might be an appropriate method for selective termination of pregnancy. Yet, optimal insertion of the electrode is required to engender a complete and irreversible cord occlusion, and ultrasound-guidance training seems necessary before current human application.

Intrauterine growth restriction in monochorionic twins

Intrauterine growth restriction (IUGR) occurs in approximately 3-10% of singleton pregnancies, in 9.1% of all twins, and in 9.9% of monochorionic twins. Spontaneous demise of the IUGR twin may occur and may result in concomitant demise or severe neurological handicap of the other twin. Currently, monochorionic twins with selective IUGR (SIUGR) are managed expectantly. Alternatively, all adverse consequences resulting from the potential demise of the SIUGR twin could be averted by unlinking the circulations between the two fetuses. The latter can be achieved by laser photocoagulation of communicating vessels or by umbilical-cord occlusion. The purpose of this chapter is to review this important entity in obstetrics.

Dilemmas in the management of twins discordant for anencephaly diagnosed at 11 + 0 to 13 + 6 weeks of gestation

OBJECTIVE

To help develop an evidence-based approach to the best management of twin pregnancies discordant for anencephaly.

METHODS

We retrospectively examined the management and outcome of 18 pregnancies discordant for anencephaly diagnosed at 11 + 0 to 13 + 6 weeks of gestation in our center. We combined these data with those from other publications. In total, there were 44 dichorionic pregnancies that were managed expectantly (n = 35) or by selective feticide (n = 9) and 19 monochorionic pregnancies that were managed expectantly. We also reviewed the literature to ascertain the outcome of monochorionic twin pregnancies undergoing cord occlusion.

RESULTS

In the 35 dichorionic pregnancies that were managed expectantly, 20 (57.1%) developed polyhydramnios at 25-31 weeks; 13 were managed expectantly, five had amniodrainage and two had selective feticide. In 34 of the 35 cases the non-anencephalic twin was liveborn at a median gestation of 36 (range, 28-39) weeks and in six (17.6%) of these it was born before 33 weeks. In the dichorionic pregnancies that had selective feticide, there was one miscarriage and eight (88.9%) live births at a median gestation of 37 (range, 30-40) weeks and in one (12.5%) of these it was born before 33 weeks. In the monochorionic pregnancies, four (21.1%) anencephalic fetuses died at 20-32 weeks and in three of these the normal co-twin also died. In the 16 (84.2%) cases resulting in the live birth of the normal twin, delivery occurred at a median gestation of 33 (range, 27-39) weeks and in six (37.5%) of these it was before 33 weeks. Ultrasound-guided bipolar cord coagulation in 92 pregnancies, mostly complicated by twin reversed arterial perfusion sequence or severe twin-to-twin transfusion syndrome, was associated with a survival rate of 77.2% and early preterm delivery rate of 31.0%.

CONCLUSION

Dichorionic twins discordant for anencephaly are best managed with serial ultrasound examinations for early diagnosis of polyhydramnios, which can then be treated either by amniodrainage or selective feticide. In monochorionic twins it is uncertain whether the best management is expectant or by cord occlusion.

Ultrasound-guided radiofrequency-driven umbilical cord occlusion: an in-vitro study

OBJECTIVES

To assess the ability and safety of radiofrequency (RF) to induce cord thermal lesions using in-vitro perfused umbilical cords.

METHODS

Nineteen human term umbilical cords were cannulated at both ends and perfused continuously with saline serum in a saline serum bath (37 degrees C). The RF electrode was then inserted into the cord close to the umbilical vein. Different RF power and temperature controls were applied to determine the optimal RF procedure in terms of cord tissue injury and safety in nine experiments. The safety of RF procedures was investigated in ten cords by measuring temperature changes at different sites close to the RF electrode insertion and the impact of RF on cord narrowing was evaluated by continuous monitoring of intraluminal pressure. Subsequent histopathological analysis was carried out in all cases.

RESULTS

The optimal RF procedure reached a temperature of 100 degrees C in 10 min. RF produced a significant increase in intraluminal pressure (from 54.2 +/- 16.4 mmHg at baseline to 118.3 +/- 42.7 mmHg after 10 min, P < 0.05). There was no significant increase in temperature next to the site of insertion during the RF procedure. Histopathological analysis confirmed a > 30% decrease in cord and vein diameter. Cord tissue lesions were characterized by damage in the vessel walls and in the surrounding Wharton's jelly.

CONCLUSION

Our results suggest that RF might be a feasible and safe technique to induce occlusion of umbilical vessels. Further in-vivo experiments are needed to assess its ability to induce a complete occlusion of the umbilical cord.

Combined sonographic and endoscopic umbilical cord occlusion in twin and triplet gestations

OBJECTIVE

To review our experience with a minimally invasive technique for umbilical cord occlusion as a method of selective feticide in monochorionic sets.

STUDY DESIGN

Umbilical cord occlusion was completed using 3 mm bipolar cautery under ultrasound guidance (3D/4D, n = 6; 2D, n = 6) with pre and post ligation endoscopic evaluation.

RESULTS

12 cases of monochorionic sets where selective feticide was performed were identified during the period 2000 to present. There were four triplet and eight twin gestations in the study cohort. Median interval from intervention to delivery was 16 weeks (range, 5-19). All co-twins survived the procedure and 15 of 16 were delivered after 33 weeks.

CONCLUSIONS

Umbilical cord occlusion in monochorionic sets can be accomplished in a minimally invasive manner with combined endoscopic and ultrasound guidance in both twin and triplet pregnancies.

Infants with Bochdalek diaphragmatic hernia: sibling precurrence and monozygotic twin discordance in a hospital-based malformation surveillance program

Congenital diaphragmatic hernia (CDH) is a common and often devastating birth defect. In order to learn more about possible genetic causes, we reviewed and classified 203 cases of the Bochdalek hernia type identified through the Brigham and Women's Hospital (BWH) Active Malformation Surveillance Program over a 28-year period. Phenotypically, 55% of the cases had isolated CDH, and 45% had complex CDH defined as CDH in association with additional major malformations or as part of a syndrome. When classified according to likely etiology, 17% had a Recognized Genetic etiology for their CDH, while the remaining 83% had No Apparent Genetic etiology. Detailed analysis using this largest cohort of consecutively collected cases of CDH showed low precurrence among siblings. Additionally, there was no concordance for CDH among five monozygotic twin pairs. These findings, in conjunction with previous reports of de novo dominant mutations in patients with CDH, suggest that new mutations may be an important mechanism responsible for CDH. The twin data also raise the possibility that epigenetic abnormalities contribute to the development of CDH.

Selective termination procedures in monochorionic pregnancies

Monochorionic twins have placental anastomoses that to varying degrees create a common circulation. This presents unique challenges for the performance of selective fetal termination in cases of twin-twin transfusion syndrome, twin reversed arterial perfusion sequence, or discordant twin abnormalities. Multiple methods of interrupting the affected twin's circulation have been attempted with variable success. One of the most frequent complications of any approach is iatrogenic preterm premature rupture of membranes. Laser coagulation in the midtrimester appears to be safe and effective; however, it is only available at limited centers. Currently, bipolar coagulation is the method of choice in the second half of pregnancy. The recently reported technique of radiofrequency ablation appears to be successful with minimal complications. Exploration of further percutaneous and noninvasive techniques, as well as interventions to decrease the morbidity arising from preterm membrane rupture, may lead to increased survival of the remaining twin and reduced risk of maternal complications.

Selective feticide in complicated monochorionic twin pregnancies using ultrasound-guided bipolar cord coagulation

OBJECTIVE

To review our experience with selective feticide in complicated monochorionic (MC) twin pregnancies, using ultrasound-guided cord coagulation with a bipolar forceps.

DESIGN

Retrospective analysis.

SETTING

All consecutive umbilical cord coagulations performed at our institution in the second trimester of pregnancy between November 1999 and 2003.

POPULATION

Consecutive cases of complicated MC pregnancies with an indication for selective termination.

METHODS

Ultrasound-guided coagulation of the umbilical cord with a 2.5-mm bipolar forceps under local anaesthesia.

MAIN OUTCOME MEASURES

Indications, gestational age at the procedure, perinatal outcome and neonatal follow up.

RESULTS

Forty-six patients with MC twin pregnancies underwent this procedure. Indications included twin reverse arterial perfusion sequence (n= 17), severe malformation in one twin (n= 7) and agonal presentation or cerebral anomalies of one twin in twin-to-twin transfusion syndrome (TTTS) after laser treatment or serial amniodrainage (n= 22). The procedure resulted in six intrauterine fetal demise (IUFD, 13%), with a rate of 41% and 3% when performed at 16-17 weeks or later, respectively (Fisher P= 0.002). Preterm rupture of the membranes (PROM) before 28 weeks and between 28 and 34 weeks occurred in 9% and 14% of the cases, respectively. All neonatal deaths (four) occurred in cases with PROM at 28 weeks or earlier. Paediatric follow up showed that all infants discharged alive but one were neurologically normal at 3-42 months, which corresponds to 70% of the 46 cases.

CONCLUSIONS

This technique is effective when the natural history is likely to severely affect the development of the normal co-twin. The overall intact survival rate was 70% and our results support justification of later surgery. Prematurity remains a significant complication of the procedure.

Discordant growth in twins

Discordant growth in twins contributes significantly to rates of perinatal morbidity and mortality. These rates vary according to chorionicity, timing of onset and severity. We have reviewed English language literature in Medline since 1980. It is clear that diagnosis of discordant growth has improved due to the use of serial ultrasound examination. Following the detection of differences in fetal size, diagnosis is facilitated by umbilical artery and fetal Doppler studies. Management options vary according to chorionicity, timing of onset and umbilical-fetal Doppler studies. The mode of delivery in discordant twins remains controversial. We conclude that ultrasound surveillance of twin gestations, combining serial biometry and selective Doppler studies, is effective in the recognition of significant intrauterine growth restriction in co-twins. Differences in etiology and management underscore the importance of establishing chorionicity routinely as soon as twin gestation is diagnosed.

Management of other complications specific to monochorionic twin pregnancies

Monochorionic (MC) twins have a 3-10-fold higher perinatal mortality and morbidity than dichorionic twins. This is largely attributable to their common vascular architecture and the high rate of discordant fetal growth, growth restriction and congenital abnormalities. In the event of a single intrauterine death (IUD), intertwin agonal transfusion results in up to a 38% risk of death and a 46% risk of neurological injury to the co-twin. This chapter addresses the management of complications unique to MC twins. The primary aim of management is to prevent single IUD or, if inevitable, prevent agonal transfusion occurring by vascular occlusive selective feticide. Older fetoscopic techniques have been replaced by the simpler ultrasound-guided techniques of interstitial laser and bipolar cord occlusion. Their application in twin reversed-arterial perfusion sequence has been associated with a 50% reduction of perinatal mortality in the pump twin. Moreover, prophylactic interstitial laser therapy in early pregnancy might obviate the technical and clinical difficulties in the presence of fetal decompensation in later pregnancy. Recent strategies to reduce the high perinatal mortality due to cord entanglement in antenatally diagnosed monoamniotic twins including medical amnioreduction and elective caesarean delivery at 32 weeks, are also discussed.