Ultrasound-guided umbilical cord occlusion using bipolar diathermy for Stage III/IV twin-twin transfusion syndrome

Clinical outcomes of fetal selective reduction in dichorionic triplet pregnancies

BACKGROUND

It is recommended to reduce triplet pregnancy containing monochorionic (MC) twins to singleton. Given that some couples with infertility are eager to retain twins, better strategy is needed to avoid obstetrical risks and satisfy their strong wish. This retrospective observational study aimed to investigate the outcomes of triplet pregnancy reduction.

METHODS

Subjects with triplet pregnancies who underwent selective reduction between 2016 and 2019 at our hospital were enrolled. A total of 66 subjects with dichorionic triplet (DCT) with MC twins and an MC singleton were divided into two groups: group A (N = 38), reduced to dichorionic diamniotic (DCDA) twins; group B (N = 28), reduced to MC diamniotic (MCDA) twins. Obstetrical and perinatal outcomes were compared between groups.

RESULTS

Group A had significantly lower rates of early miscarriage (0% vs 14.3%, p = 0.028), cesarean section (81.6% vs 100%, p = 0.041), and late premature delivery (21.1% vs 45.4%, p = 0.047) than group B. Significantly higher rates of full-term delivery (71% vs 36.4%, p = 0.009) and take-home baby (100% vs 78.6%, p = 0.004), and higher gestational age at delivery (median: 38 [36.9, 39.0] vs 35.8 [34.4, 37.0] weeks, p < 0.001), total neonatal weight (2899.7 ± 647.6 vs 2354.4 ± 651.8 g, p < 0.001), weight of twins (2550 vs 2350 g, p = 0.039), and weight of larger neonate in twins (2790 vs 2500 g, p = 0.045) were observed in group A compared to group B.

CONCLUSION

DCT reduced to DCDA twins confers better pregnancy outcomes than into MCDA twins. This might benefit for triplet pregnancy subjects who strongly want to retain fraternal twins.

Directive clinique no 440 : Prise en charge de la grossesse gémellaire monochoriale

OBJECTIF

Cette directive clinique passe en revue les données probantes sur la prise en charge de la grossesse gémellaire monochoriale normale et compliquée.

POPULATION CIBLE

Les femmes menant une grossesse gémellaire ou multiple de haut rang. BéNéFICES, RISQUES ET COûTS: L'application des recommandations de cette directive devrait améliorer la prise en charge des grossesses gémellaires (ou multiples de haut rang) monochoriales compliquées et non compliquées. Ces recommandations aideront les fournisseurs de soins à surveiller adéquatement les grossesses gémellaires monochoriales ainsi qu'à détecter et prendre en charge rapidement les complications associées de façon optimale afin de réduire les risques de morbidité et mortalité périnatales. Ces recommandations impliquent une surveillance échographique plus fréquente en cas de grossesse monochoriale qu'en cas de grossesse bichoriale. DONNéES PROBANTES: La littérature publiée a été colligée par des recherches dans les bases de données PubMed et Cochrane Library au moyen de termes MeSH pertinents (Twins, Monozygotic; Ultrasonography, Prenatal; Placenta; Fetofetal Transfusion; Fetal Death; Fetal Growth Retardation). Les résultats ont été restreints aux revues systématiques, aux essais cliniques randomisés et aux études observationnelles. Aucune date limite n'a été appliquée, mais les résultats ont été limités aux contenus en anglais ou en français. MéTHODES DE VALIDATION: Les auteurs principaux ont rédigé le contenu et les recommandations et ils se sont entendus sur ces derniers. Le conseil d'administration de la SOGC a approuvé la version définitive aux fins de publication. Les auteurs ont évalué la qualité des données probantes et la force des recommandations en utilisant le cadre méthodologique GRADE (Grading of Recommendations Assessment, Development and Evaluation). Voir l'annexe A en ligne (tableau A1 pour les définitions et tableau A2 pour l'interprétation des recommandations fortes et conditionnelles [faibles]). PROFESSIONNELS CONCERNéS: Spécialistes en médecine fœto-maternelle, obstétriciens, radiologues, échographistes, médecins de famille, infirmières, sages-femmes, résidents et autres fournisseurs de soins de santé qui s'occupent de femmes menant une grossesse gémellaire ou multiple de haut rang. RéSUMé POUR TWITTER: Directive canadienne (SOGC) pour le diagnostic, la surveillance échographique et la prise en charge des complications de la grossesse gémellaire monochoriale (p. ex., STT, TAPS, retard de croissance sélectif, cojumeau acardiaque, monoamnionicité et mort d'un jumeau). DÉCLARATIONS SOMMAIRES: RECOMMANDATIONS.

Guideline No. 440: Management of Monochorionic Twin Pregnancies

OBJECTIVE

This guideline reviews the evidence-based management of normal and complicated monochorionic twin pregnancies.

TARGET POPULATION

Women with monochorionic twin or higher order multiple pregnancies.

BENEFITS, HARMS, AND COSTS

Implementation of these recommendations should improve the management of both complicated and uncomplicated monochorionic (and higher order multiple) twin pregnancies. They will help users monitor monochorionic twin pregnancies appropriately and identify and manage monochorionic twin complications optimally in a timely manner, thereby reducing perinatal morbidity and mortality. These recommendations entail more frequent ultrasound monitoring of monochorionic twins compared to dichorionic twins.

EVIDENCE

Published literature was retrieved through searches of PubMed and the Cochrane Library using appropriate MeSH headings (Twins, Monozygotic; Ultrasonography, Prenatal; Placenta; Fetofetal Transfusion; Fetal Death; Fetal Growth Retardation). Results were restricted to systematic reviews, randomized controlled clinical trials, and observational studies. There were no date limits, but results were limited to English or French language materials.

VALIDATION METHODS

The content and recommendations were drafted and agreed upon by the principal authors. The Board of the SOGC approved the final draft for publication. The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and conditional [weak] recommendations).

INTENDED AUDIENCE

Maternal-fetal medicine specialists, obstetricians, radiologists, sonographers, family physicians, nurses, midwives, residents, and other health care providers who care for women with monochorionic twin or higher order multiple pregnancies.

TWEETABLE ABSTRACT

Canadian (SOGC) guidelines for the diagnosis, ultrasound surveillance and management of monochorionic twin pregnancy complications, including TTTS, TAPS, sFGR (sIUGR), acardiac (TRAP), monoamniotic twins and intrauterine death of one MC twin.

SUMMARY STATEMENTS

RECOMMENDATIONS.

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.

Monochorionic diamniotic twins: What do I tell the prospective parents?

Monochorionic diamniotic twins occur in about 1 in 300 pregnancies. Compared with dichorionic twins, they face increased risks because of the shared circulation. In about 15%, an imbalance in blood exchange occurs, such as twin-twin transfusion syndrome and twin anemia polycythemia sequence. In this review, we summarize the latest evidence on the management of monochorionic diamniotic twin pregnancies and their specific complications, with a focus on information that is relevant for prospective parents.

Outcomes following selective fetoscopic laser ablation for twin-to-twin transfusion syndrome: a single-centre experience

INTRODUCTION

Fetoscopic laser photocoagulation (FLP), a treatment option for twin-to-twin transfusion syndrome (TTTS) in monochorionic twin pregnancies, is currently the treatment of choice at our centre. We previously reported on our experience of FLP from June 2011 to March 2014. This paper audits our fetal surgery performance since then.

METHODS

15 consecutive patients who underwent FLP for Stage II-III TTTS before 26 weeks of gestation from June 2011 to January 2017 were retrospectively reviewed, consisting of five cases from our initial experience and ten subsequent cases. Perioperative, perinatal and neonatal outcomes were analysed.

RESULTS

Of 15 pregnancies, 10 (66.7%) and 5 (33.3%) were for Stage II and III TTTS respectively, with FLP performed at an earlier Quintero stage in the later cohort. Overall mean gestational ages at presentation, laser and delivery were comparable between the cohorts at 19.7 (15.4-24.3) weeks, 20.3 (16.3-25.0) weeks and 31.2 (27.6-37.0) weeks, respectively. 2 (13.3%) cases had intra-amniotic bleeding and 1 (6.7%) had iatrogenic septostomy. 1 (6.7%) case had persistent TTTS requiring repeat FLP, and another (6.7%) had preterm premature rupture of membranes at seven weeks post procedure. The overall perinatal survival rate was 21 (75.0%) out of 28 infants. One mother underwent termination of pregnancy for social reasons at 1.4 weeks post procedure. Double survival occurred in 8 (57.1%) out of 14 pregnancies, while 13 (92.9%) had at least one survivor.

CONCLUSION

FLP requires a highly specialised team and tertiary neonatal facility. Continual training improves maternal and perinatal outcomes, ensuring comparable standards with international centres.

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.

Fetoscopic laser photocoagulation in twin-to-twin transfusion syndrome: experience from a single institution

INTRODUCTION

Twin-to-twin transfusion syndrome (TTTS) is the most common serious complication of monochorionic (MC) twin pregnancies, with perinatal mortality rates of up to 90% if untreated. This study aimed to review the perinatal and perioperative outcomes of MC twin pregnancies treated for TTTS by fetoscopic laser photocoagulation (FLP) since its introduction at KK Women's and Children's Hospital (KKH), Singapore, in 2011.

METHODS

This was a retrospective review of five consecutive patients who underwent FLP of placental anastomoses for TTTS at KKH from June 2011 to March 2014. FLP was offered to patients who were diagnosed with TTTS of at least Quintero Stage II before 26 weeks of gestation. The main outcome measures were perioperative complications and perinatal survival rates.

RESULTS

Five sets of MC twin pregnancies underwent FLP during the study period - three pregnancies were diagnosed with Stage III TTTS and two pregnancies with Stage II TTTS. Median gestational ages at initial presentation, laser photocoagulation and delivery were 19 (range 17-20) weeks, 20 (range 19-23) weeks and 29 (range 28-34) weeks, respectively. One patient had bleeding into the amniotic cavity intraprocedurally. Overall, the perinatal survival rate, double-infant survival rate and survival rate for at least one twin were 60% (6/10 fetuses), 40% (2/5 twins) and 80% (4/5 twins), respectively.

CONCLUSION

FLP is a feasible treatment for TTTS, with minimal maternal complications. Perinatal survival rates of this patient group that was managed at our centre were comparable to those of international centres.

The History of Treatment of Twin-to-Twin Transfusion Syndrome

Historical suggestions of twin-to-twin transfusion syndrome (TTTS) date back to the early 17th century. Placental anastomoses were first reported in 1687; however, it was Schatz who first identified their importance in 1875. He recognized ‘the area of transfusion’ within the ‘villous district’ of the placenta, which he named the ‘third circulation’. This article describes how the management of TTTS has evolved as we have gained a more sophisticated understanding and appreciation of the complex vascular anastomoses that exist in monochorionic twin placentae. Currently, fetosopic laser occlusion is the preferred treatment option for TTTS.

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.

Systematic review and metaanalysis of perinatal outcomes after radiofrequency ablation and bipolar cord occlusion in monochorionic pregnancies

The aim of this study was to analyze perinatal outcomes after selective reduction in monochorionic pregnancies with the use of either radiofrequency ablation (RFA) or bipolar cord occlusion (BCO). This was a systematic review and metaanalysis that included all studies with ≥5 cases that described perinatal outcomes after BCO or RFA that were identified in PubMed, Embase, Web of Science, COCHRANE, CINAHL, Academic Search Premier, Science Direct, and MEDLINE that were published between 1965 and July 2014. For count data, incidence risk ratios (IRR; 95% confidence interval [CI]) were calculated with BCO as the reference standard. The analysis included 481 cases of BCO and 320 cases of RFA from 17 studies. The mean median gestations at procedure were 21.1 ± 1.2 weeks (BCO) and 18.8 ± 2.5 weeks (RFA; P = .03). The rate of cotwin death was higher in the RFA group (14.7%) vs the BCO group (10.6%; IRR, 1.38; 95% CI, 0.93-2.05; P = .11). The live birth rate was 81.3% for the RFA group and 86.7% in the BCO group (IRR, 0.93; 95% CI, 0.80-1.09; P = .41). BCO had higher neonatal death rates (8.1%) vs RFA (4.5%; IRR, 0.56; 95% CI, 0.30-1.04; P = .07). Overall survival was 76.8% for RFA and 79.1% for BCO (IRR, 0.97; 95% CI, 0.82-1.14; P = .72); however, none of these differences were statistically significant. Preterm premature rupture of membranes occurred in 17.7% of RFA cases and 28.2% of the BCO cases (IRR, 0.63; 95% CI, 0.43-0.91; P = .01). The mean median gestational age at delivery was 34.7 ± 1.7 weeks in the RFA group and 35.1 ± 1.6 weeks in the BCO group. Our data do not demonstrate clearly the superiority of 1 procedure over the other. The clinical situation and preference of the operator are important considerations. Rates of preterm delivery and preterm premature rupture of membranes remain substantial for both procedures.

Outcome following selective fetal reduction in monochorionic and dichorionic twin pregnancies discordant for structural, chromosomal and genetic disorders

BACKGROUND

To investigate the indications for offering selective fetal reduction in monochorionic (MC) and dichorionic (DC) twins and to correlate obstetric outcome with the antenatal procedure.

METHODS

All cases of MC and DC twins discordant for structural anomalies and for chromosomal/genetic abnormalities were included. Selective reductions performed for twin-to-twin transfusion syndrome or growth restriction were excluded. For DC twins, feticide was achieved using intracardiac injection of potassium chloride (KCl). For MC twins, bipolar cord occlusion (BCO), interstitial laser or radiofrequency ablation (RFA) was used.

RESULTS

There were 121 twin pregnancies discordant for structural and chromosomal abnormalities. Only 88 (56 were MC twins and 32 were DC twins) had selective reduction. For both MC and DC twins, the leading indication for selective reduction was structural anomalies with CNS malformations the most common. For all MC fetal reduction techniques, the overall pregnancy loss rate (<24 weeks) was 8.9% with RFA having the lowest procedure loss rate (7.7%). The preterm delivery rate was lowest with reduction in DC pregnancies. The live birth rates for MC twins were >87% and 100% for DC twins.

CONCLUSIONS

Selective reduction in MC pregnancies carries an increased procedure-related and preterm delivery rate compared with DC pregnancies. The main indication for selective reduction was structural malformations, with a predominance of CNS anomalies.

Fetal cardiac function in recipient twins undergoing fetoscopic laser ablation of placental anastomoses for Stage IV twin-twin transfusion syndrome

OBJECTIVE

Cardiac dysfunction is common in the recipient fetus of twin-twin transfusion syndrome (TTTS). In this study, we aimed to document the severity of fetal cardiac dysfunction in Stage IV TTTS (fetal hydrops) and assess evolution of cardiac function longitudinally after fetoscopic laser surgery.

METHODS

We reviewed obstetric ultrasound examination data, pre- and postoperative echocardiograms and neonatal outcomes for 22 cases of Stage IV TTTS undergoing fetoscopic laser ablation of placental anastomoses between 1998 and 2011. Myocardial performance index, atrioventricular valve flow patterns, ventricular shortening fraction, ventricular hypertrophy, outflow tract obstruction and venous Doppler waveforms were assessed.

RESULTS

Nineteen fetuses (86.4%) had ascites, eight (36.4%) had pleural effusions, nine (40.9%) had a pericardial effusion and 12 (54.5%) had subcutaneous edema at presentation. Preoperatively, cardiac function was grossly abnormal in all. Eight fetuses (36.4%) had functional pulmonary atresia and one (4.5%) had functional aortic atresia. Seventy-seven percent of recipient fetuses survived until birth. Postoperative echocardiographic follow-up (mean, 26 days) showed that indices of fetal cardiac function improved considerably, but never completely normalized. Six of the eight fetuses with functional pulmonary atresia (75.0%), as well as the fetus with functional aortic atresia, survived to birth. In all cases, the functional atresia resolved within 48 h of laser ablation therapy and none had structural valve anomalies at birth. All fetal effusions resolved after the laser.

CONCLUSIONS

Fetoscopic laser ablation of placental anastomoses reverses cardiac dysfunction and valvulopathy, even in the most severe cases of TTTS. However, recovery takes longer than in early stage disease.

Bipolar cord coagulation for selective feticide in complicated monochorionic twin pregnancies: 118 consecutive cases at a single center

OBJECTIVE

To review the experience of performing selective feticide with bipolar cord coagulation (BCC) in complicated monochorionic (MC) twin pregnancies at a single center.

METHODS

This was a retrospective analysis of BCC performed using 3-mm bipolar forceps under ultrasound control in cases complicated by twin-to-twin transfusion syndrome, selective growth restriction, discordant anomaly or twin reversed arterial perfusion sequence.

RESULTS

The series comprised 118 cases with a median gestational age at the time of the procedure of 22 (range, 16-30) weeks. There were 14 (12%) intrauterine deaths of the cotwin, eight (7%) miscarriages and one (1%) termination of pregnancy. When BCC was performed before 19 weeks of gestation, the rate of miscarriage was 45%, whereas it was 3% (P < 0.001) when BCC was performed after 19 weeks. Preterm prelabor rupture of membranes (PPROM) occurred in 45 (38%) cases. The median interval between BCC and PPROM was 4 (interquartile range, 2-9) weeks. In 15 (13%) cases, PPROM occurred within 2 weeks after the procedure. Median gestational age at delivery was 34 (range, 24-41) weeks. The median birth weight was 2103 (range, 480-3875) g. Neonatal death occurred in 11 (9%) cases, and two (2%) children had severe neurologic morbidity. The overall survival rate was 71% (84/118).

CONCLUSION

BCC is an effective procedure in complicated MC twin pregnancies for selective feticide or when one fetus is severely jeopardized and delivery is not yet an option. Better outcomes can be achieved when this procedure is performed after 19 weeks.

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.

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

OBJECTIVE

We sought to assess long-term neurodevelopment of children who were treated prenatally as part of the Eurofoetus randomized controlled trial.

STUDY DESIGN

The study population was composed of 128 cases of twin-to-twin transfusion syndrome (TTTS) included and followed up in France. Survivors were evaluated by standardized neurological examination and by Ages and Stages Questionnaires (ASQ). Primary outcome was a composite of death and major neurological impairment.

RESULTS

A total of 120 children (47%) were alive at the age of 6 months and were followed up to the age of 6 years. At the time of diagnosis, only treatment and Quintero stage were predictors of a poor outcome (hazard ratio, 0.61; 95% confidence interval, 0.41-0.90; P = .01 and hazard ratio, 3.23; 95% confidence interval, 2.19-4.76; P < .001, respectively). Children treated by fetoscopic selective laser coagulation (FSLC) had higher ASQ scores at the end of follow-up (P = .04).

CONCLUSION

FSLC was significantly associated with a reduction of the risk of death or long-term major neurological impairment at the time of diagnosis and treatment.

Monochorionic twin pregnancy: screening, pathogenesis of complications and management in the era of microinvasive fetal surgery

OBJECTIVE

The management of monochorionic (MC) twin pregnancies varies in different medical centers. This paper compares screening methods to predict the complications of the MC twin pregnancy and different treatment methods.

METHODS

We performed a literature search without language restriction in Cochrane library and PubMed (1970-2009). Case series and cohort screening studies, pathogenesis and management of complications of MC pregnancy were included.

RESULTS

Elevated risk for intrauterine fetal death (IUFD) and twin-to-twin transfusion syndrome (TTTS) can be detected sonographically. Monitoring of MC pregnancies at increased risk and regular training sessions for the operating team combined with reduced fetoscopic amniotic membrane damage increase fetal survival rate from laser coagulation to nearly 100% for at least one fetus and to 90% for both.

CONCLUSION

Monitoring of MC pregnancies at increased risk and laser treatment of TTTS in medical centers with sufficient experience might improve neonatal outcome.

DIAGNOSIS AND MANAGEMENT OF SELECTIVE FETAL GROWTH RESTRICTION IN MONOCHORIONIC TWINS

Selective fetal growth restriction (sFGR) has been reported to occur in about 10–15% of monochorionic (MC) twins. The diagnosis of sFGR has been based on variable criteria including estimated fetal weight (EFW), abdominal circumference and/or the degree of fetal weight discordance. Recent studies tend to use a simple definition which includes the presence of an EFW less than the 10th percentile in the smaller twin. Some would argue that the intertwin fetal weight discordance should be included in the definition. Indeed this factor plays a major role in the complications presented by these cases. While the majority of cases with one fetus below the 10th percentile usually will also present with a large intertwin EFW discordance, the contrary is not always true. Thus, it is possible to find MC twins with remarkable intertwin EFW discordance but the EFW of both fetuses are still within normal ranges. Although it appears to be common sense that a large intertwin discrepancy might represent a higher risk for some of the complications described later in this review, there is no consistent evidence to support this notion. Therefore, due to its simplicity, a definition based on an EFW below 10th percentile in one twin is probably the most useful for clinical and research purposes.

The pediatric surgeons' contribution to in utero treatment of twin-to-twin transfusion syndrome

OBJECTIVE

To evaluate the outcome of twin-to-twin transfusion syndrome (TTTS) treated using a combination of endoscopic fetal surgery-specific techniques and surgical restraint.

SUMMARY BACKGROUND DATA

TTTS is a condition of identical twins that, if progressive and left untreated, leads to 100% mortality. The best treatment option is obliteration of the intertwin placental anastomoses, but fetal surgery carries significant maternal and fetal risks. Even if successful, percutaneous endoscopic laser ablation of placental vessels (LASER) causes premature rupture of membranes (PROM) in 10% to 20% of pregnancies. Patient selection is particularly critical because the progression of the disease is unpredictable. This has prompted many to intervene early, yielding survival rates of >=1 twin of 75% to 80%.

METHODS

We developed a minimally invasive approach to fetal surgery, a unique membrane sealing technique and a conservative algorithm that reserves intervention for severe TTTS. Pregnancies with TTTS (stages I-IV) managed in the last 8 years were reviewed. LASER was offered in stage III/IV only.

RESULTS

Ninety-eight cases of TTTS were managed in a pediatric surgery/maternal-fetal medicine collaborative Fetal Treatment Program-39 were observed (40%) and 59 underwent LASER (60%). Survival of >= twin was seen in 82.7%, and overall survival was 69.4%. These survival rates are similar to, or better than, other comparable series with similar stage distribution (low:high stage ratio 1:1) in which all patients underwent LASER. PROM rate was 4%.

CONCLUSIONS

Reserving LASER treatment for severe TTTS results in outcomes similar to, or better than, LASER for all stages. Applying fetal surgery-specific endoscopic techniques, including port-site sealing, reduces postoperative complications.

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.

Survival after laser surgery for twin-to-twin transfusion syndrome: when are they out of the woods?

PURPOSE

Severe, progressive twin-to-twin transfusion syndrome (TTTS) is associated with near-100% mortality if left untreated. Endoscopic laser ablation of placental vessels (ELA) is associated with 75% to 80% survival of at least one twin. The actuarial risk of fetal demise after ELA has not yet been described.

STUDY DESIGN

A retrospective cohort study from 2 centers on a consecutive series of 163 sets of monochorionic twins with severe TTTS (18 Quintero stage I, 55 stage II, 71 stage III, 19 stage IV) who underwent ELA. Actuarial survival was calculated and stratified for donor vs recipient and according to stage.

RESULTS

Median gestational age at diagnosis was 20.1 weeks; median operative time was 60 minutes. Overall survival was 63%, and survival of at least one twin was seen in 76% of pregnancies. Of fetal demises, 10% occurred within 48 hours after ELA, and 90% of all fetal demises occurred within 1 month. There was a 10% survival advantage of recipients over donors. Survival was similar for stages I, II, and IV (75%-80%), compared with 55% for stage III.

CONCLUSIONS

Actuarial survival curves for TTTS confirms a greater burden on donor than on recipient but not at a previously reported 2:1 ratio. The current staging system does not accurately reflect post-ELA mortality risk. The unexpected higher mortality in stage III may reflect a more acute progression of the disorder in this group, an adverse effect of LA on an as yet unknown subgroup with stage III or, alternatively, preoperative demise of fulminant stage IV patients, leaving a stage IV subgroup with a more benign course and better outcome.

Interstitial laser therapy for fetal reduction in monochorionic multiple pregnancy: loss rate and association with aplasia cutis congenita

OBJECTIVE

To evaluate experience with interstitial laser therapy for intrafetal vascular ablation in monochorionic (MC) multiple pregnancy.

METHODS

MC pregnancies that underwent fetal reduction between 1998 and 2007 by interstitial laser therapy were reviewed. Indications were twin reversed arterial perfusion sequence (TRAP) (n = 10), twin-to-twin transfusion (6), discordant abnormality (7) or growth (1) and high-order multiples (6).

RESULTS

Thirty pregnancies treated at 15 weeks (median, range: 11 weeks-20 weeks, 5 days) had no technical failures but four manifested procedure-related amniorrhexis. Four of 38 remaining fetuses suffered intrauterine death (IUFD) within 24 h, giving an early procedure-related fetal loss rate of 10% per pregnancy and 11% per fetus. A further five IUFDs occurred within 2 weeks, giving a maximum procedure-related loss rate of 27% per pregnancy and 24% per fetus. Median gestation at delivery was 37 weeks (18 weeks, 1 day-41 weeks, 3 days) for pregnancies continuing > 2 weeks. Perinatal survival was 26 of 38 (68%) in nonreduced fetuses. Two of 26 neonates (8%) were diagnosed with aplasia cutis congenita (ACC).

CONCLUSION

Interstitial laser therapy in complicated MC pregnancies carries significant risks of unintended fetal loss and may be associated with ACC.

Amniotic band syndrome following septostomy in management of twin-twin transfusion syndrome: a case report

Septostomy, a rupture of the diamniotic membrane separating monozygotic twins essentially creating a monoamniotic gestation, is a potential therapeutic modality for twin-twin transfusion syndrome (TTTS). This may be associated with complications including cord entanglement or complete rupture of the membranes. We report a case of severe amniotic band syndrome with cord amputation after septostomy. A 33-year-old woman with a Mo-Di twin pregnancy was diagnosed with TTTS at 18 weeks of gestation. Septostomy as well as amnioreduction were performed at 24 weeks of gestation. A repeat cesarean delivery was performed at 31 weeks resulting in a live recipient baby of 1340 g and a dead donor with amniotic band syndrome. The donor showed pieces of membrane tightening both legs. The right thigh became entangled in the bands connecting to the umbilical cord of the live fetus. The umbilical cord of the dead twin was completely amputated, whereas the umbilical cord of the live infant was also entrapped within the amniotic band resulting in small diameter and some degree of stricture. This is the first report of a rare but serious complication following septostomy.

Fetal surgery

Fetal surgery has emerged from the realm of medical curiosity into an exciting, multidisciplinary specialty now capable of improving patient outcomes for a wide variety of diseases. Recent advances allow prenatal providers to both accurately diagnose and treat many fetal anomalies while maintaining maternal safety. As the initial postnatal health care providers to the majority of these newborns, neonatologists need to be familiar with some of the more recent state-of-the-art procedures currently being used. In this review, the authors discuss the prenatal evaluation process and various operative approaches (ie, open hysterotomy, fetoscopy, and percutaneous) to conduct fetal surgery. They then analyze the effectiveness of some of the more established and experimental prenatal therapies that are being performed for a number of fetal anomalies, including twin-twin transfusion syndrome, thoracic malformations, airway obstruction, congenital diaphragmatic hernia, myelomeningocele, and aortic valve stenosis.

Endoscopic laser surgery in severe second-trimester twin-twin transfusion syndrome: a three-year experience from a Latin American center

OBJECTIVE

In order to assess the outcome of pregnancies complicated by severe second trimester twin-twin transfusion syndrome (TTTS) undergoing treatment with endoscopic laser surgery, we reviewed our experience following the implementation of an institutional fetal surgery program.

METHODS

Patients presenting with monochorionic-diamniotic twin pregnancies complicated by severe TTTS before 26 weeks of gestation were offered endoscopic laser surgery to coagulate placental vascular anastomoses. Using regional anesthesia and guided by real-time sonography, anastomoses were identified and selectively coagulated. At the end of the procedure, amniodrainage was performed to restore normal amniotic fluid volume. Follow-up and delivery were carried out at the referring institutions. Six-month follow-up was performed in all cases.

RESULTS

During a 3-year period from September 2003 to December 2006, 33 consecutive cases of severe TTTS were operated on at a median gestational age of 21 weeks (range 17-25). Nine (27.3%) cases were classified as stage II, 21 (63.6%) as stage III, and three (9.1%) as stage IV. The placenta was anterior or predominantly anterior in 15 (45.5%) of the cases. Overall, both twins were born alive in 16 (48.5%) cases, only one twin was born alive in 11 (33.3%), and neither was born alive in the remaining six (18.2%). Therefore, 81.8% (27 of 33) of the pregnancies resulted in at least one liveborn infant. Among them, the mean gestational age at delivery was 32 weeks (range 23-38) and the mean birthweight of the liveborn infants was 1591 g (range 350-3800). Thirty-four infants survived the perinatal period, yielding an overall perinatal survival rate of 51.5%, with 75.8% (25 of 33) of the pregnancies resulting in at least one perinatal survivor. All neonatal deaths were associated with extreme prematurity.

CONCLUSIONS

This preliminary experience suggests that selective laser coagulation appears to be a good treatment option in cases of monochorionic twin pregnancies complicated by severe TTTS. However, technical skills and adequate equipment are required for implementing a fetal surgery program. Auditing outcomes during the learning curve would help in identifying potential problems.

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.

Pregnancy outcomes following bipolar umbilical cord cauterization for selective termination in complicated monochorionic multiple gestations

OBJECTIVE

To review pregnancy and childhood outcomes following selective termination by ultrasound guided bipolar umbilical cord cauterization (UCC) in complicated monochorionic multifetal pregnancies.

STUDY DESIGN

Consenting patients (27 of 49, 55%) had review of pregnancy history and pediatric development in the surviving twin following selective UCC.

RESULTS

UCC was performed at 21.2 +/- 2.8 weeks gestational age, followed by a liveborn delivery (n = 28) at 34.4 +/- 4.7 weeks. Mean birth weight was 2,218 +/- 926 g. Complications included preterm labor (25.0%), premature rupture of membranes (17.8%), placental abruption (10.7%) and chorioamnionitis (7.1%). Perinatal mortality was 10.3% in continuing fetuses. However, 96.2% of pregnancies achieved livebirths with 96% of neonates showing apparently normal development between ages 1.5 and 5 years.

CONCLUSION

Bipolar UCC is a reasonably safe and effective treatment for selective termination in complicated monochorionic pregnancies.

A classification system for selective intrauterine growth restriction in monochorionic pregnancies according to umbilical artery Doppler flow in the smaller twin

OBJECTIVES

To evaluate a classification of selective intrauterine growth restriction (sIUGR) in monochorionic (MC) twins based on the characteristics of umbilical artery (UA) Doppler flow in the smaller twin, in terms of association with clinical outcome and with the pattern of placental anastomoses.

METHODS

One hundred and thirty-four MC twins diagnosed with sIUGR at 18-26 weeks were classified as Type I (UA Doppler with positive diastolic flow, n = 39), Type II (persistent absent or reversed end-diastolic flow, n = 30) and Type III (intermittent absent or reversed end-diastolic flow, n = 65). Perinatal outcome, placental sharing and the pattern of anastomoses were compared with those in 76 uncomplicated MC twins.

RESULTS

Mean gestational age at delivery was 35.5 (range, 30-38) weeks in controls, 35.4 (range, 16-38) weeks in Type I, 30.7 (range, 27-40) weeks in Type II (P < 0.0001) and 31.6 (range, 23-39) weeks in Type III (P < 0.0001) pregnancies. Fetal weight discordance was significantly higher in Type II (38%) and Type III (36%) than in Type I (29%) (P < 0.0001) pregnancies. Deterioration of the growth-restricted fetus occurred in 90% of Type II cases, compared with 0% and 10.8% of Types I and III, respectively (P < 0.001). Unexpected intrauterine fetal death of the smaller twin occurred in 15.4% of Type III cases, compared with 2.6% and 0% of Types I and II respectively (P < 0.05). Parenchymal brain lesions in the larger twin were observed in 19.7% of Type III cases and less than 5% in the other groups (P < 0.05). Placental discordance (larger/smaller) was 1.3 in controls, compared with 1.8, 2.6 and 4.4 in Types I, II and III, respectively (P < 0.01). The proportion of cases with arterioarterial anastomoses > 2 mm in diameter was 55% in controls, 70% in Type I, 18% in Type II (P < 0.01) and 98% in Type III (P < 0.01).

CONCLUSION

sIUGR can be classified on the basis of umbilical artery Doppler into three types that correlate with different clinical behavior and different patterns of placental anastomoses. This classification may be of help in clinical decision-making and when comparing clinical studies.

Impact of selective laser ablation of placental anastomoses on the cardiovascular pathology of the recipient twin in severe twin-twin transfusion syndrome

OBJECTIVES

We investigated the impact of selective laser ablation on the cardiovascular pathology of the recipient twin in twin-twin transfusion syndrome.

STUDY DESIGN

Fetal echocardiograms and medical records were reviewed from 22 pregnancies with severe twin-twin transfusion syndrome where echocardiography was performed before and after laser.

RESULTS

Before laser, cardiomegaly associated with right and/or left ventricular hypertrophy without ventricular dilatation, was observed in most cases. Right ventricular and left ventricular systolic dysfunction (shortening fraction <28%) was present in 59% and 27%, respectively, and diastolic dysfunction (based on inflow and venous Dopplers) in 73%. Shortly after laser, biventricular systolic function improved significantly and diastolic function tended to improve (50%, P = .06). Functional pulmonary atresia, secondary to right ventricular systolic dysfunction, resolved in 2 of 2 cases at post-laser echocardiography. On serial assessment, diastolic function was normal in 7 of 10, hydrops regressed in 4 of 5, and neither progressive myocardial hypertrophy nor anatomical right ventricular outflow obstruction were found.

CONCLUSIONS

Selective laser ablation in severe twin-twin transfusion syndrome acutely improves biventricular systolic function and tends to improve diastolic function in the recipient twin.

The management of multiple pregnancy

The epidemic of multiple pregnancy continues albeit in a different form with twin pregnancies predominating. Determination of chorionicity is the key to management and regular monitoring by ultrasound is a hallmark of quality care. All multiple pregnancies should be offered first trimester screening by nuchal translucency for aneuploidy. MC twins should be scanned at fortnightly intervals to allow complications such as twin-twin transfusion or IUGR to be detected and referral made to a fetal medicine centre. Maternal complications are common and vigilance is required for their detection. Although planned vaginal delivery can often be achieved, mothers must be prepared for the substantial risk of requiring a caesarean section as this currently occurs in the majority.

Port insertion and removal techniques to minimize premature rupture of the membranes in endoscopic fetal surgery

BACKGROUND

Premature rupture of membranes (PROM) remains a significant complication of fetal surgery. Rates of 40% to 100% have been reported after both open and endoscopic fetal surgery. We describe a technique of endoscopic port insertion and removal that minimizes trauma to the membranes.

METHODS

Twenty-seven consecutive patients undergoing endoscopic laser ablation for twin-to-twin transfusion syndrome were reviewed. In each case, a minilaparotomy was performed, and the amniotic cavity was entered under direct vision of the uterus using a Seldinger technique. The entry site was carefully dilated to accommodate a 4.0-mm-diameter cannula. A gelatin sponge plug was placed at port removal. Postoperative management and outcome were evaluated.

RESULTS

Median gestational age at operation was 21.3 weeks. Median operating time was 60 minutes. One patient delivered intraoperatively because of fetal distress. Seventeen (65.4%) patients required postoperative tocolysis (median duration, 12 hours). Median postoperative gestation was 6.5 weeks (range, 1-20 weeks). Only 1 (4.2%) of 24 patients with successful gelatin sponge placement developed PROM.

CONCLUSIONS

Meticulous technique and atraumatic insertion and removal of ports help minimize the risk of postoperative amniotic leak after endoscopic fetal surgery. Our PROM rate of 4.2% contrasts sharply with previously reported rates after similar operations.

Pregnancy and infant outcome of 80 consecutive cord coagulations in complicated monochorionic multiple pregnancies

OBJECTIVE

This study was undertaken to document pregnancy and infant outcome after cord coagulation with laser and/or bipolar as a technique for selective feticide in complicated monochorionic multiple pregnancies.

STUDY DESIGN

Prospective follow-up study in 2 tertiary fetal medicine centers.

RESULTS

Eighty cases were included in the study (73 twins, 7 triplets). The survival rate was 83% (72/87). There were 9 intrauterine fetal deaths (10%), 5 within 24 hours and 4 between 4 and 10 weeks after the procedure. There was 1 termination of pregnancy because of chorioamnionitis. Median gestational age at delivery was 35.4 weeks, with 79% of patients delivering after 32 weeks. Preterm prelabor rupture of the membranes before 25 weeks accounted for all perinatal deaths (n = 5). Of the children older than 1 year of age (n = 67), 62 (92%) have a normal development.

CONCLUSION

Cord coagulation is an effective method for selective feticide in monochorionic multiple pregnancies.

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.

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.

Monochorionic triplet pregnancy complicated by severe fetofetal transfusion

We report two cases of fetofetal transfusion in monochorionic triamniotic triplet pregnancies. Case 1: At 23 weeks' gestation an amnioreduction was carried out. Three days later, the donor triplet died in utero. Immediately after that, a cardiotocogram of the triplet who had been thought to be unaffected by the fetofetal transfusion, showed a non-reassuring fetal status. Although cesarean section was carried out, none of the triplets survived. Case 2: At 24 weeks' gestation a woman was transferred to our center because of fetofetal transfusion in monochorionic triplets. Cesarean section was carried out. However, the recipient died on the 75th day after birth, and the others had neurological problems. Previous reports on fetofetal transfusion in triplets are very limited. The prognosis of this condition has been reported to be severe, irrespective of chorionicity, gestational age at delivery, maternal age, and parity. When managing a monochorionic or dichorionic triplet pregnancy, serial and careful ultrasound examination is mandatory to find early symptoms of this serious condition.

A randomized trial of amnioreduction versus septostomy in the treatment of twin-twin transfusion syndrome

OBJECTIVE

Left untreated, severe twin-to-twin transfusion syndrome (TTTS) presenting in the early second trimester of pregnancy is often associated with significant maternal morbidity and almost universal perinatal loss. Removal of excessive amounts of amniotic fluid through serial amniocenteses (amnioreduction) has been the mainstay of therapy. We sought to compare amnioreduction to intentional perforation of the intervening twin membrane (septostomy).

STUDY DESIGN

Pregnant women with TTTS before 24 weeks' gestation were randomly assigned to serial amnioreduction or septostomy. A single puncture technique under ultrasound guidance was used for the septostomy. The primary outcome measure was survival to neonatal discharge, and was assessed based on the number of pregnancies or the number of fetuses as appropriate.

RESULTS

The study was terminated at the planned interim analysis stage after 73 women were enrolled. This was because the rate of survival of at least 1 infant was similar in the amnioreduction group compared to the septostomy group (78% vs 80% of pregnancies, respectively; RR=0.94, 95%CI 0.55-1.61; P=.82). Patient undergoing septostomy were more likely to require a single procedure for treatment (64% vs 46%; P=.04).

CONCLUSION

Although overall perinatal survival is not enhanced, septostomy offers the advantage of often requiring a single procedure compared to serial amnioreduction in the treatment of severe twin-to-twin transfusion syndrome.

Increased latency of absent end-diastolic flow in the umbilical artery of monochorionic twin fetuses

OBJECTIVE

To determine if absent end-diastolic flow (AEDF) in the umbilical artery (UA) has a longer latency in monochorionic (MC) twin fetuses compared to singleton or dichorionic twin (DC) fetuses.

METHODS

One hundred and eight pregnancies with a fetus with AEDF were reviewed: 47 MC and 17 DC twin pregnancies and 44 singletons. Because twin-twin transfusion syndrome (TTTS) is a potential confounder when determining latency, subgroup analysis was also performed on the 21 MC affected pregnancies without TTTS. Latency of AEDF (in days) was defined as the difference between the gestational age at diagnosis of AEDF and gestational age at delivery or intrauterine death.

RESULTS

Latency was similar in MC twins (median, 39 days) and DC twins (30 days) but longer compared to singletons (11 days; P = 0.0001). After excluding pregnancies with TTTS, latency in non-TTTS MC twins (54 days) was longer than in both singletons and DC twins. This was due to an earlier gestational age at AEDF in non-TTTS MC twins of 20 weeks compared to 27 weeks in both singleton and DC twins because median gestational age at delivery was similar in MC twins, DC twins and singletons.

CONCLUSIONS

The latency period of UA AEDF is longer in MC twins than in singletons. Our data suggest that in MC twin fetuses without TTTS, AEDF begins earlier and lasts about twice as long as in DC twin fetuses, which is consistent with placental insufficiency not being the sole factor mediating abnormal UA waveforms in MC placentation. This observation is important in counseling and managing twin pregnancies discordant for AEDF.

Monochorionic twin pregnancies

The monochorionic placenta should be considered a developmental malformation and, as such, represents one of the most common birth defects. Great strides are being made to unravel the progression of nature's successful attempt at human cloning through fission. Critical to any strategy to reduce the perinatal morbidity and mortality associated with monochorionic placentas is early detection. Intense surveillance in at risk pregnancies will provide a better understanding of their natural progression, improve the prognosis with early intervention, and ultimately provide the key to prevent many of the complications unique to the monochorionic placenta.