Monochorionic Monoamniotic Pregnancy Research Articles

Monochorionic monoamniotic twin pregnancies.

Monochorionic monoamniotic (MCMA) twin pregnancy is rare and associated with increased complication rates when compared with singletons, dichorionic and monochorionic diamniotic pregnancy in general. Monoamnionicity presents an enormous challenge following its accurate diagnosis, where the absence of an inter-twin membrane subsequently results in cord entanglement and consistently fluctuating foetal position. Furthermore, the detection of twin-twin transfusion syndrome (TTTS) in MCMA pregnancy can be challenging in the absence of amniotic fluid volume discordance without the presence of the inter-twin dividing membrane. Early surveillance of foetal anatomy permits early recognition of foetal structural anomalies, the twin reversed arterial perfusion (TRAP) sequence and conjoined twins. However, the evidence on how best to monitor MCMA pregnancies remains inadequate, though observational studies have demonstrated that once surveillance is initiated, the potential risk of foetal death decreases significantly. In-utero foetal demise can be acute and unpredictable in MCMA pregnancies, despite close surveillance. Elective preterm delivery is usually advocated when the risk of foetal loss upon continuing the pregnancy outweighs the risk of prematurity - around 33 weeks' gestation by caesarean section. Nevertheless, the optimal prenatal surveillance regimen and prompts for delivery have yet to be defined.

Outcomes of Monoamniotic Twin Pregnancies from the First Trimester Onward

Introduction: Monochorionic monoamniotic (MCMA) twins are rare, and information is lacking on pregnancy outcomes from the first trimester onward. This study compares the pregnancy and neonatal outcomes between MCMA and monochorionic diamniotic (MCDA) twin pregnancies from the first trimester onward. We also report on the outcomes of MCMA twin pregnancies continuing after 28 weeks and on the neurodevelopmental outcomes of MCMA twins. Methods: A retrospective single-center cohort study of MCMA and MCDA twin pregnancies followed from the first trimester with a fortnightly ultrasound scan. We excluded pregnancies with a major anomaly diagnosed on the first-trimester ultrasound scan. MCMA twin pregnancies were offered inpatient monitoring from 28 weeks onward, and an elective cesarean section was advised between 32 and 33 weeks. MCDA pregnancies were managed as inpatients only if medically indicated, and an elective birth between 36 and 37 weeks was recommended. Results: We analyzed the outcomes of 52 MCMA and 671 MCDA twin pregnancies. In MCMA twins, the fetal and neonatal survival rate was 81/104 (78%) versus 1,192/1,342 (89%) in MCDA twins (p = 0.016). Double intrauterine demise (IUD) was more common in MA than in DA pairs (13% vs. 3%) (p = 0.002). No IUD occurred in the 40 MCMA pregnancies that continued after 28 weeks, but five women (13%) required an urgent cesarean section for fetal distress. Thirty-eight of 52 eligible infants (73%) underwent a neurodevelopmental assessment. Thirty-three (87%) had cognitive and motor development scores within normal limits. Four infants had mild cognitive or motor impairment, and one infant was diagnosed with spastic diplegia. Conclusion: MCMA twins are associated with decreased survival rates compared to MCDA due to increased rates of double IUD. After 28 weeks, about one in eight women required an urgent delivery for fetal distress. Most infants had normal neurodevelopmental outcomes.

Fused yolk sacs in a case of forked umbilical cord in monochorionic diamniotic twin pregnancy: sonoembryological implications

Forked cord (FC), which presents as a fused insertion of two umbilical cords into a monochorionic placenta, is a rare entity, especially in monochorionic diamniotic (MCDA) twin pregnancies. Herein, we describe a case of a MCDA pregnancy with FC, which showed characteristic findings on first-trimester ultrasound examination. A healthy 29-year-old nulliparous woman presented at 8 weeks of gestation following a positive result on pregnancy self-testing. Transvaginal ultrasound revealed two fetuses with active heartbeats and both had their own amniotic membrane, suggesting a MCDA pregnancy (Figure 1a). Noteworthy was that the two yolk sacs were completely fused (Figure 1b) and the connecting stalks, which are the site of the future umbilicus, were located in close proximity to one another (Figure 1c). On transabdominal ultrasound screening at 16 weeks of gestation (Figure 2a), FC was diagnosed but no other abnormalities were detected. The pregnancy course was uneventful and healthy female babies, weighing 2285 g and 2345 g, were born vaginally at 36 weeks. The umbilical and placental inspection revealed that each umbilical cord had two arteries and one vein, which fused near the placental surface, where the amniotic membranes divided the amniotic cavities (Figure 2b). Most cases of previously reported FC were observed in monochorionic monoamniotic (MCMA) twin pregnancies, which were frequently accompanied by an acardiac twin1, 2. Thomas et al. was the first to report an antenatally diagnosed case of FC in an otherwise uncomplicated MCDA pregnancy, in which FC was recognized at 30 weeks, and healthy infants (weighing 2460 g and 2490 g) were delivered at 35 weeks3. Frisch et al. reported a case of FC in a MCMA pregnancy diagnosed at 10 weeks, in which the twin pair (weighing 1169 g and 935 g) was delivered at 29 weeks because of abnormal fetal heart rate patterns4. In our case, which is the third report in the literature of liveborn twins with prenatal diagnosis of FC, the unique findings were the fused yolk sacs, with the amniotic membranes dividing the two fetuses as early as 8 weeks of gestation, in addition to the closely located connecting stalks. From an embryological viewpoint, the folding of the embryo and the expansion of the amniotic cavity, which bring the connecting stalk and yolk sac together to form the umbilical cord, occur after 9 weeks of gestation5. We postulate that our findings at 8 weeks of the fused yolk sacs and the closely located connecting stalks might be forecasting subsequent FC, even when the amniotic membranes dividing two embryos are visualized. As for the blood volume balance between the twins, we agree with the speculation of Thomas et al. and Frisch et al. that a fenestration between the two umbilical vein walls may have had a protective effect on the hemodynamic status of the twins3 and that FC itself in MCMA and MCDA pregnancies does not necessarily cause adverse perinatal outcome4. Our first-trimester findings provide new insights into sonoembryology, especially in relation to umbilical cord development from connecting stalks.

Early Ultrasound Identification of Cord Entanglement in Monochorionic Monoamniotic Twin Pregnancy.

Monochorionic monoamniotic pregnancy are considered high risk gestations and the fetal outcome is at times unpredictable. Correct diagnosis and counselling are extremely important, especially regarding the risk of unexpected fetal demise. We present the rare case of a monochorionic monoamniotic twin pregnancy with early identification of cord entanglement and the characteristic ultrasound findings in the first trimester of pregnancy.

Neonatal Morbidity of Monoamniotic Twin Pregnancies: A Systematic Review and Meta-analysis.

This study was aimed to report the incidence of neonatal morbidity in monochorionic monoamniotic (MCMA) twin pregnancies according to gestational age at birth and type of management adopted (inpatient or outpatient). Medline and Embase databases were searched. Inclusion criteria were nonanomalous MCMA twins. The primary outcome was a composite score of neonatal morbidity, defined as the occurrence of at least one of the following outcomes: respiratory morbidity, overall neurological morbidity, severe neurological morbidity, and infectious morbidity, necrotizing enterocolitis at different gestational age windows (24-30, 31-32, 33-34, and 35-36 weeks). Secondary outcomes were the individual components of the primary outcome and admission to neonatal intensive care unit (NICU). Subanalysis according to the type of surveillance strategy (inpatient compared with outpatient) was also performed. Random effect meta-analyses were used to analyze the data. A total of 14 studies including 685 MCMA twin pregnancies without fetal anomalies were included. At 24 to 30, 31 to 32, 33 to 34, and 35 to 36 weeks of gestation, the rate of composite morbidity was 75.4, 65.5, 37.6, and 18.5%, respectively, the rate of respiratory morbidity was 74.2, 59.1, 35.5, and 12.2%, respectively, while overall neurological morbidity occurred in 15.3, 10.2, 4.3, and 0% of the cases, respectively. Infectious morbidity complicated 13, 4.2, 3.1, and 0% of newborns while 92.1, 81.6, 58.7, and 0% of cases required admission to NICU. Morbidity in pregnancies delivered between 35 and 36 weeks of gestation was affected by the very small sample size of cases included. When comparing the occurrence of overall morbidity according to the type of management (inpatient or outpatient), there was no difference between the two surveillance strategies (p = 0.114). MCMA pregnancies are at high risk of composite neonatal morbidity, mainly respiratory morbidity that gradually decreases with increasing gestational age at delivery with a significant reduction for pregnancies delivered between 33 and 34 weeks. We found no difference in the occurrence of neonatal morbidity between pregnancies managed as inpatient or outpatient. · MCMA pregnancies are at high risk of composite neonatal morbidity, mainly respiratory morbidity.. · Neonatal morbidity gradually decreases with increasing GA at delivery, mostly between 33 and 34 weeks.. · There is no difference in the occurrence of neonatal morbidity between in- or outpatient management..

Monoamniotic twins pregnancy complicated by a fetal congenital heart defect – a challenge for perinatal decisions

Abstract Objectives To analyze pregnancy management and postnatal follow-up in monochorionic monoamniotic (MCMA) pregnancies complicated by a congenital heart defect (CHD) in one twin and to compare the results with current recommendations concerning time and mode of delivery in MCMA pregnancies. Cases presentation Perinatal medical records of five pairs of monoamniotic twins referred to Fetal Cardiology Department were analyzed. 5 out of 23 MCMA pregnancies (21.7%) were complicated by CHD in one fetus. Cesarean section (CS) was performed between 32 and 35 weeks of gestation (WoG). 9 out of 10 neonates had respiratory failure, including all patients with CHD. Twins without congenital abnormalities spent median 21 days (range 10–40 days) in neonatal units. Patients with CHD were transferred to cardiology departments on average 6th day of life. All were operated on later than term-born neonates, 4 out of 5 required stage surgery and their median stay in the hospital was 75 days (range 48–106 days). Conclusions According to current recommendations, delivery in MCMA pregnancies should be scheduled at 32–34 weeks. In cases complicated by CHD in one twin, such early delivery complicates surgical treatment and may affect the final outcome. Low body weight and respiratory disorders increase the risk of complications in the perioperative period and prolong hospitalization.

Latencia al parto tras cerclaje de emergencia en gestación múltiple

IntroductionCurrent guidelines support the use of physical-examination indicated cerclage (PEIC) as a treatment for cervical insufficiency and membrane exposure in single pregnancies. However, PEIC in twin pregnancies is a controversial issue as no data from random clinical trial are available to demonstrate its efficacy. Few studies suggest that PEIC may prolong pregnancy also in twin pregnancies. The aim of this study was to evaluate the results of twin pregnancies that underwent a PEIC in our health centre. Material and methodsA retrospective review was performed on women that underwent a PEIC from 2007-2016 in our centre. Women were not eligible if they were carrying foetuses with major foetal anomalies, more than two foetuses or monochorionic-monoamniotic pregnancies, or three or more foetuses or requesting an elective termination of pregnancy. Primary outcomes: latency to spontaneous delivery and gestational age (GA) at delivery. Secondary outcomes: neonatal mortality and Neonatal Intensive Care Unit admission, preterm premature rupture of membranes (PPROM), chorioamnionitis and cerclage displacement. ResultsThe study included a total of 17 women. The median (inter-quartile range) gestational age at delivery was 27.1 (24.5-32.3) weeks, and median (inter-quartile range) latency, from cervical cerclage to delivery, was 43 (21-64) days. There were 4/17 (23.5%) cases of delivery before 24 weeks of pregnancy, and 2/26 (7.7%) cases of neonatal death. DiscussionThese results suggest that latency to delivery after PEIC in twins is remarkable. Therefore, it could be considered as an optional management. Nevertheless, evidence based on random clinical trial is required to make firm recommendations on its formal use.

Perinatal mortality, timing of delivery and prenatal management of monoamniotic twin pregnancy: systematic review and meta-analysis.

To quantify the rate of perinatal mortality in monochorionic monoamniotic (MCMA) twin pregnancies, according to gestational age, and to ascertain the incidence of mortality in pregnancies managed as inpatients compared with those managed as outpatients. MEDLINE, EMBASE and CINAHL databases were searched for studies on monoamniotic twin pregnancy. The primary outcomes explored were the incidence of intrauterine death (IUD), neonatal death (NND) and perinatal death (PND) in MCMA twins at different gestational-age windows (24-30, 31-32, 33-34, 35-36 and ≥ 37weeks of gestation). The secondary outcomes were the incidence of IUD, NND and PND in MCMA twins according to the type of fetal monitoring (inpatient vs outpatient), and the incidence of delivery ahead of schedule. Random-effects model meta-analyses were used to analyze the data. Twenty-five studies (1628 non-anomalous twins reaching 24 weeks of gestation) were included. Single and double intrauterine deaths occurred in 2.5% (95% CI, 1.8-3.3%) and 3.8% (95% CI, 2.5-5.3%) of cases, respectively. IUD occurred in 4.3% (95% CI, 2.8-6.2%) of twins at 24-30 weeks, in 1.0% (95% CI, 0.6-1.7%) at 31-32 weeks and in 2.2% (95% CI, 0.9-3.9%) at 33-34 weeks of gestation, while there was no case of IUD, either single or double, from 35 weeks of gestation. In MCMA twin pregnancies managed mainly as inpatients, the incidence of IUD was 3.0% (95% CI, 1.4-5.2%), while the corresponding figure for those managed mainly as outpatients was 7.4% (95% CI, 4.4-11.1%). Finally, 37.8% (95% CI, 28.0-48.2%) of MCMA pregnancies were delivered before the scheduled time, due mainly to spontaneous preterm labor or abnormal cardiotocographic findings. MCMA twins are at high risk of perinatal loss during the third trimester of pregnancy, with the large majority of such losses occurring as apparently unexpected events. Inpatient management seems to be associated with a lower rate of mortality, although further studies are needed in order to establish the appropriate type and timing of prenatal assessment in these pregnancies. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Prenatal Diagnosis and Management of Ectopia Cordis: Varied Presentation Spectrum

Background: Ectopia cordis (EC) is a congenital anomaly associated with heart defects and extracardiac malformations. Objectives: We determined the various presentations of EC diagnosed in our center between 2010 and 2017. Results: Seven fetuses from six pregnancies with EC were detected, five during the first trimester. Three were from multiple pregnancies, and both twins had EC in one monochorionic-monoamniotic pregnancy. Abdominal wall defects were detected in six fetuses. Kyphoscoliosis, cephalocele, clubfoot and short umbilical cord were other abnormalities. Five fetuses were terminated, one fetus died in utero, and one baby died on day two of life. Postnatal evaluation performed in all cases additionally detected cleft lips/palates in two fetuses and tetralogy of Fallot in one. Conclusion: Outcome is poor for these fetuses, EC can occur in a multiple pregnancy, most of the abnormalities can be identified in the first trimester and fetopsy continues to add information to the intrauterine diagnosis.

Management of monochorionic monoamniotic twins: case reports and a review of literatures

Monochorionic monoamniotic (MCMA) twins are rare but are associated with higher morbidity and mortality rates than monochorionic diamniotic (MCDA) twins. Although the prenatal prognosis of MCMA pregnancy has improved with advanced prenatal care, no consensus has been reached for the management for MCMA twins. Here, the authors report two cases of MCMA twin pregnancies diagnosed at 30 weeks of gestation and complicated with congenital heart disease, respectively, with a review of literature on MCMA twin pregnancies.

A Rare Mimicker in the Placenta.

A 24-year-old primigravida with monochorionic monoamniotic pregnancy presented to our institution at 31+3 weeks of gestation with leaking per vaginum. The ultrasound findings were that of an enlarged and cystically dilated placenta, which raised the possibility of a differential diagnosis of partial mole. In view of foetal distress she was taken up for emergency caesarean section. Two healthy female twins were delivered with no features of Beckwith Wiedermann syndrome. On gross examination the placenta weighed 800 gm and measured 17x15x2.5cm. The two umbilical cords attached measured 20cm and 24cm respectively [Table/Fig-1]. Foetal surface showed prominent, dilated blood vessels. The maternal surface was intact with cotyledons. Tiny, white nodules were seen on the foetal side. The cut surface of the placenta was beefy red with no pale areas. A focal area showed pinkish white vesicle like area [Table/Fig-2]. [Table/Fig-1]: Enlarged placenta (M) 17x15x2.5cm with two umbilical cords. [Table/Fig-2]: Placenta showing multiple grape like vesicles. The umbilical cords showed three vessels each. Multiple sections from the placenta showed villi of varying sizes [Table/Fig-3]. Some of the stem villi appeared markedly hydropic with stromal fibroblast proliferation. Concentric fibrosis was seen around the blood vessels [Table/Fig-4]. There was thick walled blood vessels with organising thrombus formation noted [Table/Fig-5]. Rest of the villi showed chorangiosis like change [Table/Fig-6]. Few villi showed central cistern formation, however, there was no trophoblastic proliferation. Sections from the villi appeared unremarkable. [Table/Fig-3]: Histopathology showed dilated stem villi (H&E 40x). [Table/Fig-4]: Histopathology showed concentric fibrosis in the villi (H&E 100x). [Table/Fig-5]: Histopathology showed organising thrombus (H & E 100x). [Table/Fig-6]: Histopathology showed increased number of blood vessels per villi, showing chorangiosis like change (H&E 200x).

Outcome After Second-Trimester Amniocentesis and First-Trimester Chorionic Villus Sampling for Prenatal Diagnosis in Multiple Gestations

The purpose of this study was to classify pregnancy loss and fetal loss as well as the influence of maternal risk factors in multiple pregnancies. Details of the procedure and pregnancy outcome of all patients were extracted from the clinical audit database of two tertiary centers. The files were collected in the time from January 1993 to May 2011. The procedure-related pregnancy and fetal loss rate was classified as all unplanned abortions without important fetal abnormalities or obstetric complications within 14 days after AC and CVS. We had a total number of 288 multiple pregnancies with a total of 637 fetuses. After the exclusion of 112 pregnancies with abnormal karyotype or fetal abnormalities detected by ultrasound as well as cases of selective feticide, repeated invasive procedures and monochorionic-monoamniotic pregnancies, 176 pregnancies and 380 fetuses were left for final analysis. Overall 132 amniocenteses and 44 chorionic villous sampling procedures were performed. The total pregnancy loss rate was 8.0 % (14/176), 6.1 % (n = 8) for amniocentesis and 13.6 % (n = 6) for CVS. The procedure-related pregnancy loss rate was 3.4 %, 2.3 % after amniocentesis (3 cases) and 6.8 % after CVS (3 cases). There was no statistical significance between the two procedures (p = 0.15). The procedure-related loss rate of 3.4 % can be compared to the rates in the literature. The higher loss rates in multiple pregnancies than in singleton pregnancies have to be discussed when counseling parents.

Perinatal outcome of twin reversed arterial perfusion sequence: A single center's experience

Objective To report our experience of using radiofrequency ablation (RFA) to treat fetuses diagnosed with twin reversed arterial perfusion (TRAP) sequence and to evaluate the perinatal outcome of pump twins. Methods Twenty-six fetuses diagnosed with the TRAP sequence were retrospectively analyzed between July 1998 and September 2011 at Asan Medical Center. Four were lost to follow-up after diagnosis and, therefore, were excluded from further evaluation. The perinatal outcomes of pump twins were evaluated by reviewing the medical records. Results Twenty-two fetuses were diagnosed with the TRAP sequence during the study period, including 15 monochorionic-diamniotic pregnancies and four monochorionic-monoamniotic pregnancies. Three patients had triplet pregnancies. The median gestational age at diagnosis was 17.4 weeks (range, 11.0 to 27.0 weeks). Of these 22 cases, in utero RFA was performed in 11 (50%), alcohol ablation in one (4.5%) and the remaining 10 (45.5%) underwent conservative management. The median gestational age at in utero intervention was 21.0 weeks (range, 17.6 to 25.0 weeks). The overall neonatal survival rate was 77% (17 of 22). The median gestational age at delivery was 37.3 weeks (range, 30.2 to 40.1 weeks). All of the surviving infants are doing well without any complications. Conclusion For fetuses with the TRAP sequence, proper in utero treatment with RFA enables to continue the pregnancy with a good prognosis.

Pregnancy Outcome of Monochorionic Twins: Does Amnionicity Matter?

To compare the fetal loss rate of monochorionic (MC) twin pregnancies according to their amnionicity. A retrospective review of all MC pregnancy outcomes in a tertiary centre. Pregnancy outcomes were compared for monochorionic monoamniotic (MCMA) versus monochorionic diamniotic (MCDA) pregnancies. 29 MCMA and 117 MCDA twin pregnancies were identified. The overall fetal loss rate was significantly higher in MCMA (23/52, 44.2%) compared to MCDA pregnancies (28/233, 12%, Chi squared = 30.03, p < .001). Kaplan-Meier analysis showed that fetal survival rate in MCDA twins were significantly higher than in MCMA twins (Log-rank Chi-squared = 27.9, p < .0005). Early pregnancy ultrasound identified the causes for these fetal losses in some MCMA twins. After exclusion of identifiable causes, the difference in fetal survival was not significant in the two groups (Log-rank chi-squared = 0.373, p = .54). The loss rate for MCMA twins is high and occurs mainly due to discordant congenital abnormality, conjoint twins or twin reversed arterial perfusion (TRAP) sequence. Although the fetal loss rate in MCDA is lower than in MCMA pregnancies, the majority of fetal loss in MCDA pregnancies cannot be predicted at the first scan at presentation. The data of this study questions the widespread policy of a difference in the scheduling of elective delivery for MCMA and MCDA twins.

Antenatal and intra-partum management of twins – a DGH experience

AimTo examine antenatal and intra-partum management of twin pregnancies, review the available guidelines and compare the current practice in our unit with recommendations.Methods3 year retrospective audit from 1 April 2007...

Monoamniotic twins in contemporary practice: a single-center study of perinatal outcomes

Objective. The previous studies of monochorionic monoamniotic (MCMA) twins reported perinatal mortality rates as high as 70–80%. The recent trends have been towards significantly improved outcomes, though results from all studies have not been consistent.Method. A retrospective cohort analysis of all MCMA pregnancies ≥20 weeks delivered in a single university institution from 2001 to 2009, using a computerised hospital database. MCMA twins are managed by a close antenatal surveillance program, preferably elective admission at 26–28 weeks, daily non-stress tests, regular assessment of fetal growth with the goal of cesarean delivery by 34 weeks.Results. Of the 25 MCMA pregnancies delivered, 98% (49/50) of twins were live-born. All women were delivered by cesarean section. There was one intrauterine fetal demise, which was secondary to anencephaly. There were three neonatal deaths, two in association with complex congenital heart disease. One twin died outside the neonatal period following cardiac surgery. In total, 28% (7/25) of pregnancies were complicated by major congenital anomalies. There was one case of mild transient twin–twin transfusion syndrome (TTTS). The overall perinatal mortality rate for non-anomalous twins was 2.4% (95% CI = 0.06%–13.59%).Conclusions. Traditionally quoted as up to 80%, perinatal mortality rates <10% for MCMA twins are achievable in contemporary practice. It is vital that these high-risk pregnancies are managed in experienced centers with close surveillance and appropriate pediatric support.

Perinatal Outcome of Conservative Management versus Fetal Intervention for Twin Reversed Arterial Perfusion Sequence with a Small Acardiac Twin

Objective: To examine the outcomes of patients with twin reversed arterial perfusion (TRAP) sequence in which the acardiac twin was ≤50% the weight of the pump twin. Methods: This was a retrospective study conducted with institutional review board approval. The records of all patients referred to UCSF for suspected diagnosis of TRAP between 1994 and 2009 were reviewed (n = 76). Patients with pregnancies complicated by TRAP with an acardiac twin ≤50% the weight of the pump twin were included (21 patients). Exclusion criteria were loss to follow-up (1 patient) and syndromic abnormalities in the pump twin (2 patients). Results: Of the 18 patients with viable pregnancies that met the criteria for analysis, 7 (39%) underwent radiofrequency ablation (RFA) of the acardiac twin and 11 (61%) underwent conservative management. None of the pump twins in either group had hydrops fetalis. Three of the 11 acardiac twins in the conservative management group did not undergo RFA because they did not have blood flow at presentation to UCSF. Survival to delivery was 100% (7/7) in the RFA group and 91% (10/11) in the conservative management group. When we eliminated from our analysis the 3 pregnancies in the conservative management group without blood flow to the acardiac twin, survival to delivery was 88% (7/8). The single death occurred in 1 of the 3 monochorionic-monoamniotic pregnancies in the conservative management group, all of whom had blood flow to the acardiac twin. There were no statistically significant differences in gestational age at delivery, birth weight or survival between the RFA and conservative management groups, even after stratification by blood flow. Conclusions: Conservative management with close monitoring appears to be a safe option for TRAP pregnancies in which the acardiac twin is ≤50% the weight of the pump twin.

Efficacy of radiofrequency ablation for twin-reversed arterial perfusion sequence

We report our experience in the treatment of patients with twin-reversed arterial perfusion (TRAP) sequence using radiofrequency ablation to stop perfusion to the acardiac twin and protect the pump twin. An IRB approved retrospective review of all patients (n = 29) who underwent percutaneous radiofrequency ablation of an acardiac twin, using ultrasound guidance and either a 14 or 17 gauge radiofrequency needle for twin-reversed arterial perfusion sequence, from 1998 to 2005, was performed by review of hospital and outpatient medical records. The outcomes of all 29 of the patients treated with radiofrequency ablation are known. Twenty-six of the patients had monochorionic-diamniotic pregnancies, whereas 2 had monochorionic-monoamniotic pregnancies. One patient had a triplet pregnancy with a monochorionic-diamniotic pair with TRAP sequence. Overall, 25 of 29 pump twins survived (86%), delivering at a mean gestational age of 34.6 weeks. Survival was 24 of 26 (92%) in monochorionic-diamniotic pregnancies with a mean gestational age of 35.6 weeks. Two women in our early experience sustained thermal injuries from the site of grounding pads. Radiofrequency ablation of the acardiac twin effectively protects the pump twin from high-output cardiac failure and death. Greater than 90% survival can be achieved in monochorionic-diamniotic pregnancies complicated by TRAP sequence with a mean gestation age at time of delivery close to term. Our limited experience in cases of monochorionic-monoamniotic TRAP sequence does not allow the determination of efficacy in this group.

Ultrasonographic signs of twin–twin transfusion syndrome in a monoamniotic twin pregnancy

Twin–twin transfusion syndrome (TTTS) is a complication of monochorionic pregnancies usually described in diamniotic but also in monoamniotic pregnancies1, 2. The syndrome is defined sonographically by the presence of polyhydramnios in one twin's sac (recipient twin) and oligohydramnios in the sac of the other twin (donor twin)3, 4. Other sonographic parameters include discordant bladder sizes, hydrops and abnormal Doppler studies of the arterial or venous circulation5. We report the case of a 24-year-old woman, gravida 2 para 1, who was referred to our department at 16 weeks of gestation with polyhydramnios in a monoamniotic monochorionic twin pregnancy. Ultrasound examination revealed discordant biometries, cord diameters and bladder sizes. Both cords were inserted on the placental margin and close to one another. Color Doppler and three-dimensional power Doppler showed large superficial anastomoses (Figure 1). An HDI 5000 (ATL, Courtaboeuf, France) ultrasound machine equipped with a 8–5 MHz broadband array was used. Doppler waveforms (umbilical artery and ductus venosus) were normal in Twin 1 (recipient) and indicated high-impedance flow in Twin 2 (donor). Follow-up at 19 weeks showed increased amniotic fluid index (32 cm) and reversed flow in the umbilical artery of Twin 2. Spontaneous resolution of polyhydramnios occurred at 26–28 weeks but biometries and bladder sizes remained discordant although the fetuses exhibited good activity and no effusion. At 29 + 4 weeks we observed biventricular cardiac hypertrophy in Twin 1 associated with tricuspid regurgitation and pulmonary artery hypertension (right ventricular pressure increased to 110 mmHg). A Cesarean section was performed at 30 weeks. Twin 1 weighed 1640 g with a 17 g/dL hemoglobin rate and he died postnatally at 22 h because of cardiac failure related to myocardial hypertrophy. Twin 2 weighed 1270 g with a 13 g/dL hemoglobin rate and he survived. Pathological examination of the placenta confirmed the monochorionic monoamniotic pregnancy with numerous vascular anastomoses (Figure 2). Three-dimensional power Doppler imaging demonstrating anastomosis (arrow) and the positions of the donor (D) and recipient (R) cords. Postnatal examination of the placenta demonstrating the discordant sizes of the donor (D) and recipient (R) cords. In this case we observed the main ultrasonographic signs of TTTS (polyhydramnios, discordance in bladder sizes and cord diameters and Doppler waveforms, arteriovenous placental anastomoses) and the evolution was consistent with an unbalanced blood flow (myocardial overload and polyglobulia (hemoglobin = 17 g/dL) in the recipient twin). In monoamniotic twin pregnancies the classical ultrasonographic sign of discordant amniotic sacs with deviated interfetal membrane can obviously not be observed. Nevertheless, polyhydramnios and discordant bladder sizes are currently considered to be sufficient evidence for the presence of unbalanced blood flow4. Some authors have attempted to explain why such a complication is rarely described in the literature. Monoamniotic and diamniotic-monochorionic placentas have different anastomotic patterns6, 7. The higher incidence of arterio-arterial anastomoses in monoamniotic twin pregnancies leads to more balanced anastomotic patterns and predicts that TTTS will occur approximately five times less often. We suggest close monitoring with fortnightly scans for all monochorionic pregnancies to detect the onset of TTTS. The first signs of TTTS based on polyhydramnios and discordant bladder sizes are easy to diagnose and warrant further investigation in a referral center to decide on the most appropriate management (observation, invasive procedures such as photocoagulation of the anastomoses, selective feticide, labor induction or Cesarean section). D. Gallot* , J.-P. Saulnier , D. Savary*, H. Laurichesse-Delmas* , D. Lemery* , * Maternal Fetal Medicine Unit, Maternité Hôtel-Dieu, CHU de Clermont-Ferrand, Boulevard Léon Malfreyt, 63003 Clermont-Ferrand cédex, France, Department of Pediatrics, Université d'Auvergne Clermont I, Hôtel-Dieu, CHU de Clermont-Ferrand, Boulevard Léon Malfreyt, 63003 Clermont-Ferrand cédex, France, JE 2447 ARDEMO, Université d'Auvergne Clermont I, Hôtel-Dieu, CHU de Clermont-Ferrand, Boulevard Léon Malfreyt, 63003 Clermont-Ferrand cédex, France

Successful selective termination at 17 weeks' gestation in monochorionic monoamniotic twin pregnancy affected by twin-twin transfusion syndrome and discordant for hypoplastic left heart syndrome

To report a successful selective feticide in a complicated monochorionic monoamniotic (MCMA) pregnancy. A case of MCMA pregnancy with severe twin-twin transfusion syndrome and discordant for hypoplastic left heart syndrome was diagnosed at 16 weeks' gestation. A complete ultrasound and fetoscopic surveillance was performed, ruling out cord entanglement and, thus, precluding the necessity of transecting the cord. The selective feticide was successfully performed by bipolar coagulation of the umbilical cord of the abnormal fetus under ultrasound guidance. The survivor twin developed normally during the rest of the pregnancy and was born at term. At 6 months of age, the infant was healthy. Selective feticide in complicated monoamniotic pregnancies can be safely performed. Cord entanglement can be confidently excluded by both ultrasound and fetoscopy, thus making the systematic transection of the umbilical cord unnecessary.