Monochorionic Diamniotic Twin Gestations Research Articles

A Case Report on Monochorionic Diamniotic Twin Gestation with Rh Negative Pregnancy

The terms "monochorionic" and "diamniotic" refer to multiple gestations with just one placental disk (or chorion) and two separate amniotic cavities, respectively. Each fetus in a monochorionic diamniotic twin pregnancy has its own amniotic sac in addition to the common placenta. PPROM is the rupture of membranes before the onset of labor and before 37 weeks of gestation. We present a case of a 33-week-old primigravida female with monochorionic diamniotic twin gestation, Rh negative pregnancy, and PPROM who presented to the labour room with a fully dilated cervix, an emergency lower segment caesarean section was performed with prolonged second stage labour, and twins were delivered.

Twin Reversed Arterial Perfusion Sequence: A Case Report and Literature Review

Twin reversed arterial perfusion sequence (TRAPS) is one of the complications of monochorionic twin gestation. It is characterised by large intertwined arterial-arterial anastomosis in which blood flows from one twin (pump twin) to the other twin (perfused twin) in a retrograde pattern.
 We report a case of monochorionic diamniotic twin gestation complicated by TRAPS in a 38-year-old G4P3 trader who was referred to the antenatal clinic of Rivers State University Teaching Hospital on account of unusual abdominal distension of one-week duration at 31 weeks gestational age. Ultrasound scan done at presentation showed a monochorionic diamniotic twin with the first twin in a transverse lie with an estimated foetal weight of 1.7kg, foetal heart rate of 150beats per minute, and Twin 2, had no foetal head, no cardiac pulsation with significant tissue swelling. A diagnosis of TRAPS was made for which she was admitted and delivered by emergency caesarean section. The pump twin was admitted into the Special Care Baby Unit (SCBU) and succumbed to cardiac failure 24 hours after delivery.
 Monochorionic pregnancy complicated by TRAPS is associated with poor foetal outcomes. Early diagnosis and adequate management will enhance clinical outcomes. The diagnosis of TRAPS requires a high index of suspicion. Clinicians and radiologists need to be aware of the features in order to make prompt diagnosis and take appropriate action which may include early referral to the fetal medicine unit for appropriate intervention and improved outcome for the pump twin.

Fetoscopic laser surgery for twin-to-twin transfusion syndrome in DCTA triplets compared to MCDA twins: collaborative study and literature review

Objective To compare the outcomes of dichorionic triamniotic (DCTA) triplets with that of monochorionic diamniotic (MCDA) twin gestations undergoing fetoscopic laser surgery (FLS) for treatment of twin-to-twin transfusion syndrome (TTTS). Methods Retrospective cohort study of prospectively collected data of consecutive DCTA triplet and MCDA twin pregnancies with TTTS that underwent FLS at two fetal treatment centers between 2012 and 2020. Preoperative, operative and, postoperative variables were collected. Perinatal outcomes were investigated. Primary outcome was survival to birth and to neonatal period. Secondary outcomes were gestational age (GA) at birth and procedure-to-delivery interval. Literature review was conducted in which PubMed, Web of Science, and Scopus were searched from inception to September, 2020. Results Twenty four sets of DCTA triplets were compared to MCDA twins during the study period. There were no significant differences in survival (no survivor, single, or double survivors) to birth and to the neonatal period of the MC twin pairs of the DCTA triplets vs MCDA twins. Median GA at delivery was approximately three weeks earlier in DCTA triplets compared to MCDA twins (28.4 weeks vs 31.4 weeks, p = .035, respectively). Rates of preterm birth (PTB) less than 32 and less than 28 weeks were significantly higher in DCTA triplets compared to twins (<32 weeks: 70.8% vs 51.1%, p = .037, respectively, and <28 weeks: 37.5% vs 20.8%, p = .033, respectively). Conclusion Perinatal survival including fetal and neonatal are comparable between DCTA triplets and MCDA twins. However, this might have resulted from the small sample size of the DCTA triplets. GA at delivery is earlier in triplets, which could be due to the nature of triplet gestation rather than to the laser procedure itself.

Dual demise following laser surgery for twin-twin transfusion syndrome: Analysis of 52 cases at a single fetal surgery center.

To evaluate all individual cases of dual twin demise following laser surgery for twin-twin transfusion syndrome (TTTS). This is an analysis of all monochorionic diamniotic twin gestations with TTTS complicated by dual demise following laser surgery from 2006 to 2019. Cases were reviewed by (1) a fetal surgeon researcher and (2) a panel of independent experienced maternal-fetal medicine specialists to code an etiology of demise for the donor and recipient, and to assess for possible preventability. Of 753 twins that underwent laser surgery for TTTS, 52 (6.9%) had postoperative dual demise. In this subgroup, gestational age at surgery was 19.5 (16.1-24.9) weeks, and 36 (69.2%) patients were Quintero stage III and IV. The most common etiology was the spectrum of disorders leading to preterm delivery, which included cervical insufficiency, preterm premature rupture of membranes, and preterm labor (44.2% and 48.1%, donor and recipient, respectively). Some degree of preventability was estimated for 23.1% of dual demises. The most common cause of dual demise post laser surgery for TTTS was preterm birth, reinforcing the need for studies regarding the etiology and prevention of post-fetoscopy prematurity. Nearly one-quarter of dual demise cases were deemed potentially preventable.

Elective fetal reduction by radiofrequency ablation in monochorionic diamniotic twins decreases adverse outcomes compared to ongoing monochorionic diamniotic twins

Multifetal pregnancy reduction is a technique used to reduce the fetal number to mitigate the risks of adverse outcomes associated with multiple gestations. Monochorionic diamniotic twin pregnancies are subject to unique complications, contributing to adverse pregnancy outcomes. Thus, patients have an option to electively reduce 1 fetus to improve outcomes. This study aimed to compare outcomes of elective reduction of monochorionic diamniotic twins by radiofrequency ablation to planned ongoing monochorionic diamniotic twins. We performed a retrospective review of 315 monochorionic diamniotic twin gestations that underwent first-trimester ultrasound within 1 institution. Planned electively reduced twins were compared with ongoing monochorionic diamniotic twins. All reductions were performed via radiofrequency ablation of the cord insertion site into the fetal abdomen. The primary outcome was preterm birth at <36 weeks' gestation. Secondary outcomes included gestational age at delivery; preterm birth at less than 37-, 34-, 32-, and 28-weeks' gestation; unintended loss; and adverse perinatal outcomes. Among 315 monochorionic diamniotic pregnancies, 14 (4.4%) underwent elective multifetal pregnancy reduction, and 301 (95.6%) were planned ongoing twins. The mean gestational age of radiofrequency ablation in the elective multifetal pregnancy reduction group was 15.1±0.68 weeks. Patients who underwent elective multifetal pregnancy reduction had significantly higher maternal age (P<.01) and were more likely to be Asian (P<.01). Moreover, they were more likely to have undergone in vitro fertilization (P=.03) and chorionic villus sampling (P<.01). There was a significantly higher rate of term deliveries in the elective radiofrequency ablation group compared with ongoing twins (gestational age, 38 weeks [interquartile range, 36.1-39.1] vs 35.9 weeks [interquartile range, 34.0-36.9]; P<.01). Patients with ongoing pregnancies had a trend of increased rate of preterm birth at <36 weeks' gestation (odds ratio, 3.4; 95% confidence interval, 1.0-12.0; P=.06), a significantly increased risk of preterm birth at <37 weeks' gestation (odds ratio, 8.0; 95% confidence interval, 2.4-26.4; P<.01), and no difference at less than 34-, 32-, or 28- weeks' gestation. All patients who underwent elective radiofrequency ablation had successful pregnancies with no pregnancy losses or terminations. Of ongoing gestations, 36 required procedures, including 16 (5.3%) medically indicated radiofrequency ablation, 14 (4.6%) laser ablation, and 6 (1.9%) amnioreductions. Furthermore, 22 patients (7.3%) with planned ongoing twins had total pregnancy loss at <24 weeks' gestation. Notably, 12 patients (4.0%) had unintended loss of 1 fetus before 24 weeks' gestation in the ongoing pregnancy cohort, and 12 patients (4.0%) had unintended loss of both fetuses before 24 weeks' gestation. Moreover, 5 patients (1.7%) in the ongoing pregnancy group had intrauterine fetal demise at >24 weeks' gestation and 10 patients (3.3%) electively terminated both fetuses. There was no significant difference in loss rates between the 2 groups. In this study of monochorionic diamniotic twins, patients who elected to undergo multifetal pregnancy reduction had significantly lower rates of preterm birth at <37 weeks and a lower trend of preterm birth at <36 weeks' gestation without an increased risk of pregnancy loss. Median gestational age at delivery was significantly higher in the elective multifetal pregnancy reduction group (38 weeks) than in the ongoing pregnancy group (35.9 weeks). Further research is needed to clarify if multifetal pregnancy reduction improves long-term outcomes.

1089 Dual demise following laser surgery for twin-twin transfusion syndrome: etiology and preventability

To describe causes and potential preventability of dual twin demise following laser surgery for twin-twin transfusion syndrome (TTTS). This is a retrospective study of consecutive monochorionic diamniotic twin gestations with TTTS complicated by dual demise following laser surgery from 2006-2019. Dual demise was defined as demise after laser surgery until 30 days after birth. Using a predefined set of criteria to classify the type of demise, to code a single cause of death for donor and/or recipient, and to assess preventability, each case was reviewed separately by: 1) a non-primary fetal surgeon (researcher), and 2) a panel of independent experienced maternal-fetal medicine specialists. Results are reported as median (range). 753 monochorionic diamniotic twins underwent laser surgery for TTTS. 52 (6.9%) had dual perinatal demise. The gestational age at surgery was 19.5 weeks (16.1-24.9). 36 (69.2%) patients were advanced stage (III and IV). Dual demise was classified as intrauterine fetal demise (IUFD), miscarriage, neonatal demise, and termination/selective reduction for each donor and recipient twin (Table 1). 28 (53.8%) of the cases of demise occurred simultaneously. Etiologies for dual demise were identified. For the donor twin, the most common cause was preterm premature rupture of membranes (PPROM)/preterm labor and complications of prematurity (24, 46.2%), low individual placental territory (12, 23.1%), and placental abruption (4, 7.7%). For the recipient twin, the most common cause was PPROM/preterm labor and complications of prematurity (28, 53.8%), unknown (8, 15.4%), and placental abruption (4, 7.7%). Preventability of dual demise was estimated at less than 15%. Dual perinatal demise after laser surgery for TTTS is an uncommon occurrence (6.9%), with a minority of cases deemed preventable. As PPROM and preterm delivery accounts for the majority of dual demises, future research should focus on prevention and treatment of this post-laser surgery complication.

Survival Outcomes by Fetal Weight Discordance after Laser Surgery for Twin-Twin Transfusion Syndrome Complicated by Donor Fetal Growth Restriction

Introduction: Management options for treatment of twin-twin transfusion syndrome (TTTS) with severe donor intrauterine growth restriction (IUGR) include fetoscopic laser surgery and umbilical cord occlusion (UCO). We studied perinatal survival outcomes in this select group after laser surgery, stratifying patients by preoperative estimated fetal weight (EFW) discordance. Methods: In this retrospective study of monochorionic diamniotic twin gestations with TTTS and selective donor IUGR who underwent laser surgery (2006–2017), preoperative EFW discordance was calculated ([(larger twin – smaller twin)/(larger twin)] × 100) and cases were divided into discordance strata. Severe EFW discordance was defined as >35%. The primary outcome was 30-day donor twin neonatal survival. Results: The 371 cases were distributed by discordance strata: ≤20% (74 [19.9%]), 21–25% (49 [13.2%]), 26–30% (68 [18.3%]), 31–35% (53 [14.3%]), 36–40% (51 [13.7%]), 41–45% (38 [10.2%]), >45% (38 [10.2%]). Donor 30-day survival declined as the discordance strata increased: 86.5, 85.7, 83.8, 75.5, 64.7, 63.2, and 65.8% (p = 0.0046); 30-day survival was inversely associated with severe discordance (>35%) (64.6 vs. 83.2%, p < 0.0001). Discussion: In TTTS cases complicated by donor IUGR with severe growth discordance, laser surgery was associated with donor survivorship greater than 60% suggesting that, in this setting, laser surgery remains a reasonable alternative treatment to UCO.

Perinatal outcomes of intrauterine transfusion for the surviving twin in monochorionic twin gestation involving a single fetal demise.

This study aimed to evaluate the feasibility and outcome of intrauterine transfusion (IUT) for the surviving co-twin in monochorionic diamniotic (MCDA) twin gestations involving single intrauterine fetal death (sIUFD). Cases of MCDA twin gestations involving emergent IUT for co-twins experiencing acute feto-fetal hemorrhage (AFFH) subsequent to sIUFD during the second trimester were reviewed. Fetal anemia was confirmed via fetal blood sampling, and perinatal data were retrieved from medical charts to determine the outcomes of surviving co-twins. A poor outcome at 28 days of age was defined as fetal death, neonatal death or neurological impairment such as severe intraventricular hemorrhage or cystic periventricular leukomalacia (PVL). This study included 16 cases of sIUFD diagnosed at a median of 22.5 weeks of gestation (range: 18-25 weeks). The median interval in hours between diagnosis of fetal demise and IUT was approximately 4.2 (0-22) hours. All cases achieved IUT without significant intraoperative complications. Four cases experienced a fetal loss of the co-twin, whereas 12 co-twins were born alive (including 9 preterm births), with only 1 poor outcome in a preterm infant with PVL. IUT may be a feasible prenatal intervention for surviving co-twins with AFFH. However, more extensive or pooled studies are needed to determine the efficacy of this intervention.

Magnetic resonance imaging of the fetal brain in monochorionic diamniotic twin gestation: correlation of cerebral injury with ultrasound staging and survival outcomes.

The current staging system of twin-twin transfusion syndrome (TTTS) is based on the ultrasound criteria and does not consider the cerebral injury. To assess the incidence of cerebral damage on fetal MRI and correlate abnormal cerebral diffusion-weighted imaging (DWI) findings with survival outcome and the ultrasound staging of TTTS. We conducted a retrospective review of MRI/DWI of fetal brains and the electronic medical records in monochorionic diamniotic twin gestations. Axial DWI of each fetal brain was performed on 1.5-tesla (T) clinical magnet with b values of 0s/mm2 and 700s/mm2. We correlated MRI/DWI abnormalities with the Quintero staging system and survival outcomes of the fetuses. Thirty-four pregnancies (68 fetuses) with 42 fetal cerebral abnormalities were identified by MRI/DWI alone. Of these 42 fetal cerebral abnormalities, 33 fetal brain lesions were visible only on DWI (n=25 donor, n=8 recipients; n=30 unilateral, n=3 bilateral; n=26 diffuse, n=7 focal). Quintero staging in these 34 pregnancies was as follows: 9 Stage I, 7 Stage II, 13 Stage III, 4 Stage IV, 1 Stage V. There was no significant correlation between the presence of cerebral infarction or hemorrhage using MRI/DWI and ultrasound staging (P=0.138). The overall survival rate was 63.2% (43/68). There was a significant correlation between the presence of cerebral infarction or hemorrhage on MRI/DWI and delivery status (P=0.009). Abnormal cerebral imaging findings on MRI/DWI from hypoxic-ischemic injury or hemorrhage can be seen at the beginning of the second trimester and do not correlate with the current ultrasound staging system; however, they do correlate with decreased survival. Fetal cerebral abnormalities could be incorporated into the TTTS staging system as an independent risk factor.

Longitudinal reference ranges for serial measurements of myocardial performance index (MPI) by conventional and pulsed-wave tissue Doppler in monochorionic diamniotic twins at 17 to 26weeks of gestation.

To describe the longitudinal changes of fetal myocardial performance index (MPI) measured by conventional Doppler (MPI) and by pulsed-wave tissue Doppler (MPI') based on a prospective cohort of uncomplicated monochorionic diamniotic twin. Single-center observational study. We measured MPI and MPI' in the right and left ventricles 3 times between 17 and 26weeks of gestation. Second-degree fractional polynomials were built to obtain the best fitting curves in relation to gestational age (weeks) for each parameter. Gestational age-specific reference values were estimated by using two-level hierarchical models. Eighty-three uncomplicated monochorionic pregnancies were included in our study with a total of 249 observations. Fetal cardiac function was measured as MPI RV and LV, MPI' RV and LV at a mean gestational age of 18+3 (range 17+1 to 19+2 ), 22+3 (21+1 to 23+5 ), and 24+3 (22+6 to 26+2 ) weeks. The reference ranges for MPI LV, MPI RV, MPI' LV, and MPI' RV at 17 to 26weeks were constructed and conditional percentiles calculated. The present study provides additional data on fetal cardiac function in uncomplicated monochorionic diamniotic twin gestations, describing the evolution of MPI and MPI' in both ventricles in uncomplicated monochorionic diamniotic pregnancies.

Survival Rate without Brain Abnormalities on Postnatal Ultrasonography among Monochorionic Twins after Fetoscopic Laser Photocoagulation for Selective Intrauterine Growth Restriction with Concomitant Oligohydramnios

Introduction: We aimed to clarify the survival rate without brain abnormalities (BA) after fetoscopic laser photoco­agulation (FLP) for monochorionic diamniotic twin gestations (MCDA) with selective intrauterine growth restriction (sIUGR) accompanied by abnormal umbilical artery (UA) Doppler waveforms and isolated oligohydramnios in the sIUGR twin. Materials and Methods: This retrospective study included 52 cases that underwent FLP. The main outcome was survival rate without BA of the twins at age 28 days. BA was defined as severe intraventricular hemorrhage and periventricular leukomalacia on postnatal ultrasonography. Results: Median gestational age at FLP was 20 (16–24) weeks. Ten cases were classified as type III based on Doppler for the UA. For all cases, including 20 cases of anterior placenta, FLP was completed without major intraoperative complications. Amnioinfusion was required in 49 cases for better fetoscopic visualization. Fetal loss occurred in 29 sIUGR twins and two larger twins, whereas one larger twin experienced neonatal death. Survival rates without BA were 44% (n = 23) for sIUGR twins and 94% (n = 49) for the larger twins. Discussion: FLP for MCDA with sIUGR presenting with oligohydramnios in the sIUGR twin might be considered a prenatal treatment option.

Third-trimester ultrasound diagnosis of twin-to-twin transfusion syndrome (TTTS) – A review of two cases

Twin‑to‑twin transfusion syndrome (TTTS) is an unbalanced net transfusion of blood between twin fetuses through placental anastomoses. It is a complication of monochorionic diamniotic (MCDA) twin gestation in which one of the twins is the donor while the other twin acts as the recipient. TTTS without treatment is a major cause of increased morbidity and mortality among MCDA twin pregnancies. Ultrasound diagnosis and staging of TTTS are based on Quintero staging which influences the choice of management. We present two cases of ultrasound diagnosed TTTS. A 27‑year‑old G2P1+0 with twin gestation who had an ultrasound scan at 34 weeks gestation, and a diagnosis of Quintero stage 1 TTTS was made. She had an emergency caesarian operation and was delivered of two live babies. A 24‑year‑old G1P0+0 with twin gestation who had an ultrasound scan at 35 weeks gestation, with a diagnosis of Quintero stage 5TTTS. The donor twin was alive while the recipient twin had hydrops fetalis with no cardiac activity. An emergency caesarian section was done and the donor twin survived. TTTS is a common complication among MCDA twins and it is a cause of increased morbidity and mortality among them. Early diagnosis through ultrasonography and prompt management will help reduce the morbidity and mortality associated with the syndrome. Keywords: Third trimester; twin‑to‑twin transfusion syndrome; ultrasound

Twin Anemia Polycythemia Sequence: A Complication of Monochorionic Diamniotic Twin Gestation [16P

INTRODUCTION: Twin anemia polycythemia sequence (TAPS) is an important prenatal complication of monochorionic twin gestations due to abnormal placental vascular anastomosis. Prenatal ultrasound is the only screening modality. Our objective was to evaluate the prediction potential of current prenatal ultrasound screening in diagnosing TAPS in monochorionic diamniotic twin gestations. METHODS: Maternal and neonatal medical records were reviewed for women with monochorionic diamniotic twins who delivered at Beaumont Hospital System (Royal Oak and Troy) from 2009-2014. Available prenatal ultrasound findings were compared with the neonatal outcomes. Postnatal TAPS diagnosis was confirmed with neonatal peripheral blood hemoglobin values. RESULTS: A total of 132 maternal charts were reviewed and 102 were used in data collection. The median maternal age was 31 years (19-45) with a median parity of 1 (0-3). Among these women 10% (n=10) had assisted reproductive technology. Median gestational age at time of delivery was 35.4 weeks (20.7-39). Median NICU stay for twin A and twin B were 9 (0-264) and 8.5 days, (0-103), respectively. Among 132 prenatal ultrasound screenings, 26% (n=32) were reported as abnormal. Thirty-three percent (n=34) of the neonates were diagnosed with anemia and polycythemia; of these neonates 29% (n=30) had anemia, 4% (n=4) had polycythemia. The sensitivity and specificity of prenatal ultrasound in the prediction of TAPS was 26% (95% CI: 13-44) and 77% (95% CI: 65-87), respectively. CONCLUSION: Current prenatal ultrasound screening guidelines have low sensitivity and specificity in predicting TAPS in monochorionic diamniotic twin gestations. New and updated prenatal screening methods may improve TAPS prediction.

Twin-twin transfusion and laser therapy.

Twin-to-twin transfusion syndrome (TTTS) is an uncommon, but dangerous, complication of monochorionic diamniotic twin gestations. The purpose of this review is to provide an update on the evolving treatments in TTTS as it pertains primarily to laser photocoagulation, as well as to provide recently published information on outcomes. The Solomon laser technique, in which selective fetoscopic laser photocoagulation is first performed and then followed by laser of the vascular equator from one side of the placenta to the other, reduces TTTS complications of twin anemia-polycythemia syndrome and recurrent TTTS. The addition of fetal echocardiography to the historical staging of TTTS adds important information that may guide future therapies. The postlaser ablation rate of neurodevelopmental delay in TTTS has recently been reported to be 14%. Cotwin demise is a significant complication of untreated TTTS and survival carries a 25% risk of cystic periventricular leukomalacia, middle cerebral artery infarction, and injury to other central nervous system structures as noted by neuroimaging. Laser therapy for TTTS is clearly the only therapy that halts the disease process, allows both fetuses an opportunity to survive and protects a surviving cotwin in the event of the demise of one twin. Laser techniques have evolved greatly over the last 25 years and recent reports with the addition of the Solomon technique appearing to reduce some postlaser complications (twin anemia-polycythemia sequence and recurrent TTTS). Future focus of TTTS therapy should be centered on understanding the pathophysiology of the disease better with improvement in staging of the disease and on comparison of different laser techniques with the overall goal of not only increasing twin survival rates but also reducing long term neurodevelopmental morbidity.

Doppler abnormalities in monochorionic diamniotic twin pregnancies with discordant growth.

We studied whether abnormal umbilical artery (UA) Doppler flow velocity waveforms occur with higher frequency in monochorionic diamniotic (MCDA) twin gestations with discordant fetal growth and whether this impacted neonatal outcome. We performed a retrospective study of MCDA twin pairs. We collected data from an electronic medical record. We classified pregnancies as discordant if there was at least 20% birth weight discordance. Abnormal UA Doppler velocity waveforms included absent or reversed end diastolic flow. We analyzed the data with chi square, Student's t-test and analysis of variance as appropriate. Seventy-three twin pairs met criteria for inclusion, including 16 with discordant growth. The discordant group was significantly more affected with twin-to-twin transfusion syndrome (TTTS) (P=0.02). The smaller fetuses in discordant pairs were more likely to display abnormal UA Doppler flow velocity waveforms (P<0.01). These neonates also had lower Apgar scores (P=0.03) and were more likely to require care in a neonatal intensive care unit. Our findings persisted after excluding pregnancies with TTTS. In MCDA twin gestations complicated by discordant growth, there is an increased frequency of abnormal UA Doppler flow velocity waveforms in small fetuses, and these neonates face clinical challenges after birth.

Outcomes of fetal intervention for primary hydrothorax

ObjectivePrimary hydrothorax is a rare congenital anomaly with outcomes ranging from spontaneous resolution to fetal demise. We reviewed our experience with fetuses diagnosed with primary hydrothorax to evaluate prenatal management strategies. MethodsWe reviewed the records of patients evaluated for fetal pleural effusions at our Fetal Treatment Center between 1996 and 2013. To define fetuses with primary hydrothorax, we excluded those with structural or genetic anomalies, diffuse lymphangiectasia, immune hydrops, and monochorionic diamniotic twin gestations. ResultsWe identified 31 fetuses with primary hydrothorax, of whom 24 had hydrops. Hydropic fetuses were more likely to present with bilateral effusions. Of all fetuses with primary hydrothorax, 21 had fetal interventions. Survival without hydrops was 7/7 (100%), whereas survival with hydrops depended on whether or not the patient had fetal intervention: 12/19 (63%) with intervention and 1/5 (20%) without intervention. Premature delivery was common (44%) among those who had fetal intervention. ConclusionsFetal intervention for primary hydrothorax may lead to resolution of hydrops, but preterm birth and neonatal demise still occur. Understanding the pathophysiology of hydrops may provide insights into further prenatal management strategies, including targeted therapies to prevent preterm labor.

Perinatal complications of monochorionic diamniotic twin gestations with discordant crown–rump length determined at mid‐first trimester

The aim of this study was to investigate the value of discordance of crown-rump length (DCRL) at mid-first trimester to predict adverse outcomes in monochorionic diamniotic twin gestations (MD). This was a retrospective cohort study of the perinatal outcome in MD pregnancies managed from the first trimester onward. DCRL was evaluated between 8 and 10 weeks of gestation. The association between DCRL and perinatal complications, including fetal death, twin-twin transfusion syndrome, severe discordant birthweight (DB), and twin anemia-polycythemia sequence, was assessed. Among 126 cases, a single fetal demise occurred in two (2%) and demise of both fetuses occurred in eight (6%). Five pregnancies (4%) were complicated with twin-twin transfusion syndrome; one case (1%) was twin anemia-polycythemia sequence and 13 (10%) were DB. Neonatal death occurred in one pair. At 28 days of age, in 115 cases (91%) both twins were alive. In 117 cases (93%), at least one twin survived until 28 days of age. DCRL >12.0% was not related to any perinatal complications but DB (P < 0.01; relative risk: 1.40; 95% confidence interval: 1.06-1.84). DCRL in MD during the mid-first trimester might be useful for predicting DB.

P13.04: Measurement variation of amniotic fluid pocket in monochorionic diamniotic twin gestations suspected of twin‐to‐twin transfusion syndrome

<scp>P13</scp>.04: Measurement variation of amniotic fluid pocket in monochorionic diamniotic twin gestations suspected of twin‐to‐twin transfusion syndrome

Yolk sac number does not predict reliably amnionicity in monochorionic twin pregnancies: a case of a monochorionic monoamniotic twin pregnancy with two distinct yolk sacs on early first‐trimester ultrasound

The dramatic increase in multiple births over the past 30 years has made multiple pregnancy one of the most common high-risk conditions encountered by obstetricians. In North America, the rate of multiple pregnancy has increased by 50–70% and this is largely attributed to advanced reproductive technologies1, 2. In monochorionic multiple gestations the determination of amnionicity is technically difficult to perform based both on the relatively late appearance of the amnion on ultrasound, typically between 8 and 10 weeks, along with the thin nature of the membrane. Previous studies have suggested that on early first-trimester ultrasound, monochorionic monoamniotic (MCMA) twin pregnancies can be reliably characterized by the presence of a single yolk sac and monochorionic diamniotic (MCDA) twins can be reliably characterized by the identification of two yolk sacs3. Accurate and early prenatal ultrasound diagnosis of amnionicity, along with enhanced prenatal/neonatal care, has been shown to decrease the mortality rates of MCMA twins from 50% to 10–20% in more recent years2. Recently, the accuracy of using yolk sac number as a means of predicting amnionicity has been challenged4-6. In a recent series of 22 cases of monochorionic multiple gestations, Shen et al.4 revealed that 85% of the 20 cases of MCDA gestations had two yolk sacs and that 15% were characterized by only a single yolk sac; a single case of MCMA was identified in this series and one yolk sac was seen. In 2010, three cases of MCMA twins characterized by the presence of two yolk sacs on first-trimester ultrasound were reported5, 6. Here, we present a fourth case of MCMA twins in which early first-trimester ultrasound demonstrated the presence of two yolks sacs with confirmed monoamnionicity in the late first trimester. A 31-year-old G1P0 Caucasian woman presented at a private fertility clinic for intrauterine insemination with donor sperm for social reasons. A transvaginal ultrasound examination (E8, GE Medical Systems, Zipf, Austria) was performed at 7 + 0 weeks for confirmation of intrauterine pregnancy. The 7-week ultrasound clearly demonstrated two distinct fetal poles and two separate yolk sacs. The crown–rump length measurements, of 7.6 mm and 7.9 mm, were consistent with the expected size for each fetal pole, and cardiac activity was present in both. The pregnancy was considered to be MCDA twin gestation at this point in time, based on the presence of two yolk sacs (Figure 1). At 9 + 2 weeks a single amniotic sac was observed with the absence of a dividing intergestational membrane (Figure 2). At 12 + 2 weeks of gestation, ultrasound demonstrated the absence of a dividing membrane between the fetuses (Figure 3). Power Doppler at this time revealed umbilical cord entanglement, confirming the diagnosis of a MCMA twin gestation (Figure 4). Transvaginal ultrasound at 7 weeks' gestation demonstrated two yolk sacs in a monochorionic twin pregnancy. Repeat transvaginal ultrasound at 9 + 2 weeks revealed a single amniotic sac and the absence of an intergestational membrane. Transvaginal ultrasound at 12 + 2 weeks demonstrated the absence of a dividing membrane. Transvaginal ultrasound at 12 + 2 weeks verified umbilical cord entanglement. This case highlights the close proximity in the sequence of development of the yolk sac and amnion and emphasizes our lack of understanding of the temporal differentiation of these structures. The almost simultaneous development of the yolk sac and amnion could explain these most recent findings that yolk sac number does not always correlate with amnionicity in monochorionic gestations. Yolk sac number should no longer be considered a reliable means of diagnosing amnionicity on early first-trimester ultrasound. The consequent clinical implications are an enhanced focus on the diagnosis of amnionicity based on the presence or absence of the intergestational amnion and the visualization of umbilical cord entanglement7, 8.

Spontaneous rupture of the dividing membrane in a monochorionic pregnancy resulting in a pseudo‐monoamniotic pregnancy with cord entanglement

During pregnancy spontaneous rupture of the dividing membrane of monochorionic diamniotic twins is extremely rare and difficult to diagnose prenatally. We report a case of pseudo-monoamniotic twins derived from monochorionic diamniotic twin gestation. A 37-year-old woman pregnant with monochorionic diamniotic twins initially confirmed by the first trimester ultrasonography, was suspected to have a dividing membrane not visualized on ultrasound examinations at 27 gestational weeks. The woman did not undergo any invasive procedure during pregnancy and did not have notable symptoms. We considered the possibility of spontaneous rupture of the dividing membrane and cord entanglement, and managed the rest of her gestational period as a monoamniotic twin gestation. Concordantly grown healthy male babies were born at 35 weeks and 1 day by elective cesarean section. The mother had complex entangled umbilical cords and a small trace of amniotic membrane in the placenta.