Ultrasound Doppler findings of a Twin Reversed Arterial Perfusion Sequence (TRAP).

Twin reversed arterial perfusion (TRAP) sequence is a rare pregnancy complication occurs in an identical twin pregnancy that share a single placenta. TRAP sequence is a twin's pregnancy includes a normal-developed viable pump fetus and an abnormal usually nonviable acardiac fetus. The nonviable acardiac fetus depends on the pump fetus for his blood supply and put the pump fetus at risk of high cardiac output heart failure and congenital anomalies with high mortality rate. Gray-scale ultrasound and color and pulsed Doppler imaging is a noninvasive accessible imaging modality for the diagnosis of TRAP sequence. Early diagnosis of such conditions is mandatory in order to apply the proper therapeutic measures and to help the normal developed pump fetus to survive. The main goal of management is to interrupt blood supply to the nonviable acardiac fetus to reduce the strain on the heart of the pump fetus thus, increase the chance of survival.

Perinatal outcome in monoamniotic twin pregnancies during a 10-year period: a single center, descriptive study.

PURPOSE: To retrospectively investigate perinatal outcome of monoamniotic twin pregnancies in a tertiary center during a 10 year period. METHODS: A retrospective analysis of all monoamniotic pregnancies managed at Karolinska University Hospital, Stockholm, Sweden 2010-2019 was performed. The primary outcomes were live birth rate, neonatal death and perinatal survival. The secondary outcomes were late miscarriage, gestational age at delivery and frequency of fetal complications. RESULTS: Twenty-two monoamniotic pregnancies, with 44 fetuses, were identified. Thirty-five of 44 fetuses (80%) were liveborn. Of 36 fetuses reaching 24 weeks gestation, 35 (97%) were liveborn. There were no neonatal deaths, thus the perinatal survival was 97%. The mean gestational age at birth was 32.5 weeks (SD ± 1.5). CONCLUSIONS: The live birth rate and perinatal survival of monoamniotic pregnancies managed at Karolinska University Hospital was high and comparable to previously published data.

Intertwin Membrane Perforation and Umbilical Cord Entanglement after Laser Surgery for Twin-Twin Transfusion Syndrome: Prevalence, Risk Factors, and Outcome.

INTRODUCTION: Perforation of the intertwin membrane can occur as a complication of fetoscopic laser surgery for twin-twin transfusion syndrome (TTTS). Data on the occurrence and the risk of subsequent cord entanglement are limited. The objective of this study was to assess the prevalence, risk factors and outcome of intertwin membrane perforation, and cord entanglement after laser surgery for TTTS. METHODS: In this multicenter retrospective study, we included all TTTS pregnancies treated with laser surgery in two fetal therapy centers, Shanghai (China) and Leiden (the Netherlands) between 2002 and 2020. We evaluated the occurrence of intertwin membrane perforation and cord entanglement after laser, based on routine fortnightly ultrasound examination and investigated the risk factors and the association with adverse short- and long-term outcomes. RESULTS: Perforation of the intertwin membrane occurred in 118 (16%) of the 761 TTTS pregnancies treated with laser surgery and was followed by cord entanglement in 21% (25/118). Perforation of the intertwin membrane was associated with higher laser power settings, 45.8 Watt versus 42.2 Watt (p = 0.029) and a second fetal surgery procedure 17% versus 6% (p < 0.001). The group with intertwin membrane perforation had a higher rate of caesarean section (77% vs. 31%, p < 0.001) and a lower gestational age at birth (30.7 vs. 33.3 weeks of gestation, p < 0.001) compared to the group with an intact intertwin membrane. Severe cerebral injury occurred more often in the group with intertwin membrane perforation, 9% (17/185) versus 5% (42/930), respectively (p = 0.019). Neurodevelopmental outcome at 2 years of age was similar between the groups with and without perforation of the intertwin membrane and between the subgroups with and without cord entanglement. CONCLUSION: Perforation of the intertwin membrane after laser occurred in 16% of TTTS cases treated with laser and led to cord entanglement in at least 1 in 5 cases. Intertwin membrane perforation was associated with a lower gestational age at birth and a higher rate of severe cerebral injury in surviving neonates.

[A case of subglottic cysts in monochorionic monoamniotic twins]. / Klinicheskoe nablyudenie razvitiya podskladkovykh kist u monokhorial'nykh monoamnioticheskikh bliznetsov.

The first observation in the world literature of the development of subglottic cysts in the larynx in monochorionic monoamniotic twins is presented. The girls were born prematurely at 34 weeks of gestation, from the first day of life for 7 and 8 days, respectively, were transferred to mechanical ventilation. At the fourth month of life, symptoms of laryngeal stenosis appeared and began to gradually progress, conservative therapy had no effect. The diagnosis of subglottic cysts was established on the basis of fibrolaryngoscopy; after endolaryngeal surgery, breathing returned to normal. This case demonstrates the importance of timely endoscopic examination of the respiratory tract in children with stridor.

Excellent perinatal outcome of monoamniotic twin pregnancy with timely diagnosis and optimal management - a retrospective cohort study.

OBJECTIVES: Monoamniotic twins represent a high-risk pregnancy requiring intense follow-up, elective birth and careful consideration of the mode and timing of delivery. We conducted this study to evaluate the perinatal and neonatal outcomes of monoamniotic twin pregnancies in the largest tertiary hospital in Finland. METHODS: This was a retrospective cohort study including all monoamniotic twin pregnancies during a 17-year period (2002-2018) managed in Helsinki University Hospital. Data on mothers and children were collected from patient files. Chorionicity and amnionicity were defined in first-trimester ultrasound screening. RESULTS: There were altogether 31 monoamniotic twin pregnancies during the study period, including four cases of conjoined twins which all underwent termination of pregnancy, and three miscarriages. In the remaining 24 pregnancies that continued past 24 weeks of gestation there was 97.9% survival (one intrauterine death). Three pregnancies were complicated with twin-to-twin transfusion syndrome. All children were delivered by cesarean section with a mean gestational age of 32 + 5 weeks (27 + 1-34 + 2 weeks). Respiratory distress syndrome (RDS) was observed in 57% (27/47) of neonates and grade I-II intraventricular haemorrhage (IVH) in 6.3% (3/47) of neonates. There were no neonatal deaths and no maternal complications. CONCLUSIONS: Monoamniotic twinning is a rare form of pregnancy and carries risks for perinatal and neonatal complications. With timely diagnosis, close monitoring in specialized feto-maternal unit and elective delivery at 32-34 weeks the outcome is usually excellent.

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.

Unilateral macrocystic dysplasia and contralateral agenesis in a monoamniotic twin.

OBJECTIVE: We present a case report of a congenital malformation of the uropoetic tract in one of the monoamniotic twins. CASE REPORT: A 24-year-old primigravida with male monochorionic monoamniotic twins was dia-gnosed with congenital malformation in fetus A at 24 weeks of gestation. Ultrasound verified macrocystic dysplasia and contralateral renal agenesis. Planned caesarean section was performed after the observational management of the patient in the 34th gestational week. In fetus B, a physiological finding was confirmed on the postpartum ultrasonography. In fetus A, CT examination of the abdomen confirmed the finding of left kidney agenesis and polycystic degeneration of the right kidney. Exitus letalis was stated on the newborns 5th day. CONCLUSION: The occurrence of the described combination of congenital malformation in monoamniotic twins is rare. When dysplasia significantly affects the function of the parenchyma, renal agenesis with multicystic dysplasia of the other kidney is a condition incompatible with life. For the intrauterine survival of the affected fetus, the normal renal function of the twin was important and thus the normal volume of amniotic fluid was maintained. As a result, the fetus did not develop extrarenal symptoms of the Potter sequence in the described case - especially pulmonary hypoplasia and the newborn was able to ventilate spontaneously. The death was caused by the consequences of renal failure associated with anuria.

Perinatal mortality and morbidity, timing and route of delivery in monoamniotic twin pregnancies: a retrospective cohort study.

PURPOSE: Monoamniotic twin pregnancies are at high risk of perinatal complications and fetal loss. The objective of this study is to describe the management and outcomes of monoamniotic twin pregnancies in a French university obstetrics department. METHODS: Retrospective review of all consecutive monoamniotic twin pregnancies managed between 1992 and 2018 in a level-3 university hospital maternity unit. Antenatal variables, gestational age and other neonatal characteristics at delivery, mode of delivery, and its reason were recorded, together with outcomes, including a composite adverse neonatal outcome. RESULTS: Overall, 46 monoamniotic twin pregnancies (92 fetuses) were identified during the study period. Among them, 27 fetal losses and 2 early neonatal deaths were reported. Congenital abnormalities accounted for 33.3% of the 27 fetal losses, and unexpected fetal deaths for 29.6%. Among the 37 women who gave birth to 65 live infants at 23 or more weeks of gestation, 17 had cesarean and 19 vaginal deliveries. Overall and composite adverse neonatal outcomes did not differ significantly for the 33 children born vaginally and the 31 by cesarean deliveries. The prospective risk of intrauterine death in all 92 fetuses reached its nadir of 1.8% at 336/7 weeks. CONCLUSION: This series confirms the still high risk of fetal and neonatal death of these twins and shows that congenital abnormalities but also unexpected fetal deaths account for the majority of pre- and postnatal mortality. Our data suggest that vaginal delivery of monoamniotic twins is safe and that delivery for uncomplicated monoamniotic twins should be considered around 33 weeks of gestation, but not later than 35 weeks.

Outcome of Monochorionic Monoamniotic Twin Reversed Arterial Perfusion Sequence Diagnosed in the First Trimester.

INTRODUCTION: The aim of this study is to evaluate the outcome of pregnancies complicated by monochorionic monoamniotic twin reversed arterial perfusion sequence (MOMA TRAP) diagnosed in the first trimester. METHODS: All patients diagnosed with MOMA TRAP sequence <14.0 weeks of gestation in a 10-year study period were retrospectively analyzed for intrauterine course and outcome. All patients were offered either expectant management or intrauterine intervention. Adverse outcome was defined as either intrauterine death (IUD), neonatal death or preterm birth <34.0 weeks of gestation. RESULTS: In the study period, 17 cases with MOMA TRAP sequence were diagnosed. Of these, 2 couples opted for termination of pregnancy. The remaining 15 were divided into 2 groups depending on the management: group A (n = 8) with expectant management and group B (n = 7) with intrauterine intervention. All fetuses in group A died before 20 weeks. Survival in group B was significantly better with 4/7 (57.1%) life births at a median of 39.6 weeks of gestation (p = 0.0256). The reasons for IUD in the 3 cases in group B were hemodynamic, strangulation, and bleeding complications during intervention. CONCLUSIONS: Intrauterine intervention in MOMA TRAP pregnancies significantly improves neonatal survival, although it is still associated with a substantial risk for IUD by hemodynamic complications or entanglement.

Spontaneous septostomy in a monochorionic-diamniotic twin gestation.

Monochorionic twin gestations are associated with a greater incidence of neonatal morbidity and mortality when compared with their dichorionic counterparts. In turn, monochorionic-monoamniotic (MCMA) gestations carry greater risks compared with monochorionic-diamniotic (MCDA) gestations. While the true incidence of spontaneous septostomy of the dividing membranes (SSDM) in MCDA twins is unknown, SSDM has been demonstrated to be associated with increased morbidity and mortality, due to functional transition from a MCDA gestation to a MCMA gestation. We report a case of SSDM in a mid-trimester MCDA gestation, review the literature, and describe how to identify and manage this complication.

Society for Maternal-Fetal Medicine Special Statement: Updated checklists for management of monochorionic twin pregnancy.

Approximately 20% of twin pregnancies are monochorionic. The management of monochorionic twin pregnancy involves several additional interventions beyond the routine management of singletons or dichorionic twins. In 2015, the Society for Maternal-Fetal Medicine posted checklists for monochorionic/diamniotic twins and monochorionic/monoamniotic twins. The Society presents updated versions of these 2 checklists reflecting recent changes in practice recommendations. Suggestions for implementing the use of the checklists into antenatal care practices are also included.

Outcome of twin-to-twin transfusion syndrome in monochorionic monoamniotic twin pregnancy: systematic review and meta-analysis.

OBJECTIVES: To explore the outcome of monochorionic monoamniotic (MCMA) twin pregnancies affected by twin-to-twin transfusion syndrome (TTTS). METHODS: MEDLINE and EMBASE databases were searched for studies reporting the outcome of MCMA twin pregnancies complicated by TTTS. The primary outcome was intrauterine death (IUD); secondary outcomes were miscarriage, single IUD, double IUD, neonatal death (NND), perinatal death (PND), survival of at least one twin, survival of both twins and preterm birth (PTB) before 32 weeks' gestation. Outcomes were assessed in MCMA twins affected by TTTS not undergoing intervention and in those treated with amniodrainage, laser therapy or cord occlusion. Subgroup analysis was performed including cases diagnosed before 24 weeks. Random-effects meta-analysis of proportions was used to analyze the data. RESULTS: Fifteen cohort studies, including 888 MCMA twin pregnancies, of which 44 were affected by TTTS, were included in the review. There was no randomized trial comparing the different management options in MCMA twin pregnancies complicated by TTTS. In cases not undergoing intervention, miscarriage occurred in 11.0% of fetuses, while the incidence of IUD, NND and PND was 25.2%, 12.2% and 31.2%, respectively. PTB complicated 50.5% of these pregnancies. In cases treated by laser surgery, the incidence of miscarriage, IUD, NND and PND was 19.6%, 27.4%, 7.4% and 35.9%, respectively, and the incidence of PTB before 32 weeks' gestation was 64.9%. In cases treated with amniodrainage, the incidence of IUD, NND and PND was 31.3%, 13.5% and 45.7% respectively, and PTB complicated 76.2% of these pregnancies. Analysis of cases undergoing cord occlusion was affected by the very small number of included cases. Miscarriage occurred in 19.2%, while there was no case of IUD or NND of the surviving twin. PTB before 32 weeks occurred in 50.0% of these cases. CONCLUSIONS: MCMA twin pregnancies complicated by TTTS are at high risk of perinatal mortality and PTB. Further studies are needed in order to elucidate the optimal type of prenatal treatment in these pregnancies. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Diagnosis of fetal defects in twin pregnancies at routine 11-13-week ultrasound examination.

OBJECTIVES: To examine the performance of the routine 11-13-week scan in detecting fetal defects in twin pregnancies and to examine if, in pregnancies with a fetal defect, compared to those with normal fetuses, there is increased incidence of nuchal translucency thickness (NT) ≥ 95th and ≥ 99th percentiles or intertwin discordance in crown-rump length (CRL) ≥ 10% and ≥ 15%. METHODS: This was a retrospective analysis of prospectively collected data in twin pregnancies undergoing routine ultrasound examination for fetal anatomy, according to standardized protocols, at 11-13 weeks' gestation between 2002 and 2019. Pregnancies with known chromosomal abnormality were excluded. The final diagnosis of fetal defect was based on the results of postnatal examination in cases of live birth and on the findings of the last ultrasound examination in cases of pregnancy termination, miscarriage or stillbirth. The performance of the 11-13-week scan in the detection of fetal defects was determined. RESULTS: The study population of 6366 twin pregnancies with two live fetuses at 11-13 weeks' gestation included 4979 (78.2%) dichorionic (DC) and 1387 (21.8%) monochorionic (MC) twin pregnancies. The main findings were: first, the overall incidence of fetal defects was higher in MC than in DC twins (2.8% vs 1.3%); second, the proportion of defects diagnosed in the first trimester was higher in MC than in DC twins (52.6% vs 27.1%); third, the pattern of defects in relation to detectability at the 11-13-week scan (always detectable, sometimes detectable and never detectable) was similar to that reported previously in singleton pregnancies; fourth, always-detectable defects included acrania, alobar holoprosencephaly, encephalocele, pentalogy of Cantrell, exomphalos, body-stalk anomaly, twin reversed arterial perfusion sequence and conjoined twins; fifth, the incidence of fetal NT ≥ 95th percentile was higher in those with than in those without a defect (16.5% vs 4.5% in DC twins and 19.2% vs 5.9% in MC twins) and this was also true for NT ≥ 99th percentile (8.3% vs 1.0% in DC twins and 15.4% vs 2.0% in MC twins); and sixth, the incidence of CRL discordance ≥ 10% was higher in those with than in those without a defect (20.2% vs 7.9% in DC twins and 33.8% vs 9.3% in MC twins) and this was also true for CRL discordance ≥ 15% (10.1% vs 1.9% in DC twins and 28.2% vs 2.8% in MC twins). CONCLUSIONS: First, fetal defects are more common in MC than in DC twin pregnancies. Second, first-trimester detection of fetal defects in DC twin pregnancies is similar to that in singleton pregnancies. Third, first-trimester detectability of defects in MC twins is higher than in DC twins. Fourth, in twin pregnancies with a fetal defect, there is higher intertwin discordance in CRL and incidence of increased NT, but the predictive performance of screening by these markers is poor. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Diagnóstico de defectos del feto en embarazos de gemelos en el examen ecográfico de rutina de las 11-13 semanas OBJETIVOS: Examinar la eficacia del examen rutinario de 11-13 semanas para detectar defectos fetales en embarazos de gemelos y examinar si, en los embarazos con un defecto fetal, en comparación con los de fetos normales, hay una mayor incidencia del grosor de la translucencia nucal (TN) ≥ percentil 95o y ≥ percentil 99o o una discordancia entre gemelos en la longitud céfalo-caudal (LCC) ≥10% y ≥15%. MÉTODOS: Este estudio fue un análisis retrospectivo de datos recogidos prospectivamente de embarazos de gemelos sometidos a exámenes ecográficos de rutina entre 2002 y 2019 para determinar la anatomía del feto, según protocolos estándar a las 11-13 semanas de gestación. Se excluyeron los embarazos con anomalías cromosómicas conocidas. El diagnóstico final de la anomalía fetal se basó en los resultados del examen posnatal en los casos de nacimientos vivos y en los hallazgos del último examen ecográfico en los casos de interrupción del embarazo, aborto o éxitus fetal. Se determinó la eficacia de la exploración de las 11-13 semanas en la detección de anomalías fetales. RESULTADOS: La población de estudio fue de 6366 embarazos de gemelos con dos fetos vivos a las 11-13 semanas de gestación e incluyó 4979 (78,2%) embarazos bicoriales (BC) y 1387 (21,8%) monocoriales (MC). Los principales hallazgos fueron: primero, la prevalencia total de defectos fetales fue mayor en los gemelos MC que en los gemelos BC (2,8% vs. 1,3%); segundo, la proporción de defectos diagnosticados en el primer trimestre fue mayor en los gemelos MC que en los gemelos BC (52,6% vs. 27,1%); tercero, la pauta de defectos en relación con la detectabilidad en la exploración de 11-13 semanas (siempre detectable, a veces detectable y nunca detectable) fue similar a la reportada previamente para los embarazos con feto único; cuarto, entre los defectos siempre detectables estaban la acrania, la holoprosencefalia alobar, el encefalocele, la pentalogía de Cantrell, el onfalocele, la anomalía del pedículo embrionario, la secuencia de perfusión arterial inversa de los gemelos y los gemelos unidos; quinto, la frecuencia del percentil de la TN fetal ≥95o fue mayor en los que tenían un defecto que en los que no lo tenían (16,5% vs 4,5% en los gemelos BC y 19,2% vs 5,9% en los gemelos MC) y esto también fue cierto para el percentil de la TN ≥99o (8,3% vs 1,0% en gemelos BC y 15,4% vs 2,0% en gemelos MC); y sexto, la frecuencia de una discordancia de la LCC ≥10% fue mayor en los que tenían un defecto que en los que no lo tenían (20,2% vs 7,9% en los gemelos BC y 33,8% vs 9,3% en los gemelos MC) y esto también fue cierto para la discordancia de la LCC ≥15% (10,1% vs 1,9% en los gemelos BC y 28,2% vs 2,8% en los gemelos MC). CONCLUSIONES: Primero, los defectos fetales son más comunes en embarazos de gemelos MC que en los de gemelos BC. Segundo, la detección en el primer trimestre de defectos fetales en los embarazos de gemelos BC es similar a la de los embarazos con feto único. Tercero, la detectabilidad en el primer trimestre de los defectos en los gemelos MC es mayor que en los gemelos BC. Cuarto, en los embarazos de gemelos con un defecto fetal, hay mayor discordancia entre los gemelos en la LCC y prevalencia de una mayor TN, pero la eficacia predictiva del cribado mediante estos marcadores es escasa.

Increased nuchal translucency at 11-13 weeks' gestation and outcome in twin pregnancy.

OBJECTIVE: To investigate the value of increased fetal nuchal translucency thickness (NT) at the 11-13-week scan in the prediction of adverse outcome in dichorionic (DC), monochorionic diamniotic (MCDA) and monochorionic monoamniotic (MCMA) twin pregnancies. METHODS: This was a retrospective analysis of prospectively collected data on twin pregnancies undergoing routine ultrasound examination at 11-13 weeks' gestation between 2002 and 2019. In pregnancies with no major defects or chromosomal abnormalities, we examined the value of increased NT ≥ 95th percentile in one or both fetuses in the prediction of, first, miscarriage or death of one or both fetuses at < 20 and < 24 weeks' gestation in DC, MCDA and MCMA twin pregnancies, second, death of one or both fetuses or neonates at ≥ 24 weeks in DC, MCDA and MCMA twin pregnancies, third, development of twin-twin transfusion syndrome (TTTS) or selective fetal growth restriction (sFGR) treated by endoscopic laser surgery at < 20 and ≥ 20 weeks' gestation in MCDA pregnancies, and, fourth, either fetal loss or laser surgery at < 20 weeks' gestation in MCDA pregnancies. RESULTS: The study population of 6225 twin pregnancies included 4896 (78.7%) DC, 1274 (20.5%) MCDA and 55 (0.9%) MCMA pregnancies. The incidence of NT ≥ 95th percentile in one or both fetuses in DC twin pregnancies was 8.3%; in MCDA twins the incidence was significantly higher (10.4%; P = 0.016), but in MCMA twins it was not significantly different (9.1%; P = 0.804) from that in DC twins. In DC twin pregnancies, the incidence of high NT was not significantly different between those with two survivors and those with adverse outcome. In MCMA twin pregnancies, the number of cases was too small for meaningful assessment of the relationship between high NT and adverse outcome. In MCDA twin pregnancies with at least one fetal death or need for endoscopic laser surgery at < 20 weeks' gestation, the incidence of NT ≥ 95th percentile was significantly higher than in those with two survivors (23.5% vs 9.8%; P < 0.0001). Kaplan-Meier analysis in MCDA twin pregnancies showed that, in those with NT ≥ 95th percentile, there was significantly lower survival at < 20 weeks' gestation than in those with NT < 95th percentile (P = 0.001); this was not the case for survival at ≥ 20 weeks (P = 0.960). The performance of screening by fetal NT ≥ 95th percentile for prediction of either fetal loss or need for endoscopic laser surgery at < 20 weeks' gestation was poor, with a detection rate of 23.5% at a false-positive rate of 8.9%, and the relative risk, in comparison to fetal NT < 95th percentile, was 2.640 (95% CI, 1.854-3.758; P < 0.0001). In MCDA twin pregnancies, the overall rate of fetal loss or need for laser surgery at < 20 weeks' gestation was 10.7% but, in the subgroups with NT ≥ 95th and NT ≥ 99th percentiles, which constituted 10.4% and 3.3% of the total, the rates increased to 24.1% and 40.5%, respectively. CONCLUSIONS: In MCDA twin pregnancies with no major fetal abnormalities, measurement of NT at the 11-13-week scan is a poor screening test for adverse pregnancy outcome. However, the finding in one or both fetuses of NT ≥ 95th percentile, and more so ≥ 99th percentile, is associated with a substantially increased risk of fetal loss or need for endoscopic laser surgery at < 20 weeks' gestation. The extent to which closer monitoring and earlier intervention in the high-risk group can reduce these complications remains to be determined. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Outcome of twin pregnancy with two live fetuses at 11-13 weeks' gestation.

OBJECTIVES: To report and compare pregnancy outcome in dichorionic (DC), monochorionic diamniotic (MCDA) and monochorionic monoamniotic (MCMA) twin pregnancies with two live fetuses at 11-13 weeks' gestation and to examine the impact of endoscopic laser surgery for severe twin-twin transfusion syndrome (TTTS) and/or selective fetal growth restriction (sFGR) on the outcome of MCDA twins. METHODS: This was a retrospective analysis of prospectively collected data on twin pregnancies undergoing routine ultrasound examination at 11-13 weeks' gestation between 2002 and 2019. In pregnancies with no major abnormalities, we compared overall survival, fetal loss at < 24 weeks' gestation, perinatal death at ≥ 24 weeks, delivery at < 37 and < 32 weeks, and birth weight < 5th percentile between DC, MCDA and MCMA twins. RESULTS: The study population of 6225 twin pregnancies with two live fetuses at 11-13 weeks' gestation with no major abnormalities included 4896 (78.7%) DC, 1274 (20.5%) MCDA and 55 (0.9%) MCMA twins. In DC twins, the rate of loss at < 24 weeks' gestation in all fetuses was 2.3%; this rate was higher in MCDA twins (7.7%; relative risk (RR), 3.258; 95% CI, 2.706-3.923) and more so in MCMA twins (21.8%; RR, 9.289; 95% CI, 6.377-13.530). In DC twins, the rate of perinatal death at ≥ 24 weeks in all twins that were alive at 24 weeks was 1.0%; this rate was higher in MCDA twins (2.5%; RR, 2.456; 95% CI, 1.779-3.389) and more so in MCMA twins (9.3%; RR, 9.130; 95% CI, 4.584-18.184). In DC twins, the rate of preterm birth at < 37 weeks' gestation in pregnancies with at least one liveborn twin was 48.6%; this rate was higher in MCDA twins (88.5%; RR, 1.824; 95% CI, 1.760-1.890) and more so in MCMA twins (100%; RR, 2.060; 95% CI, 2.000-2.121). In DC twins, the rate of preterm birth at < 32 weeks was 7.4%; this rate was higher in MCDA twins (14.2%; RR, 1.920; 95% CI, 1.616-2.281) and more so in MCMA twins (26.8%; RR, 3.637; 95% CI, 2.172-6.089). In DC twin pregnancies with at least one liveborn twin, the rate of a small-for-gestational-age neonate among all liveborn twins was 31.2% and in MCDA twins this rate was higher (37.8%; RR, 1.209; 95% CI, 1.138-1.284); in MCMA twins, the rate was not significantly different (33.3%; RR, 1.067; 95% CI, 0.783-1.455). Kaplan-Meier analysis showed a significant difference in survival in MCDA and MCMA twins, compared to DC twins, for both the interval of 12 to < 24 weeks' gestation (log-rank test, P < 0.0001 for both) and that of ≥ 24 to 38 weeks (log-rank test, P < 0.0001 for both). Endoscopic laser ablation of intertwin communicating placental vessels was carried out in 127 (10.0%) MCDA twin pregnancies for TTTS and/or sFGR and, in 111 of these, surgery was performed at < 24 weeks; both fetuses survived in 62 (55.9%) cases, one fetus survived in 25 (22.5%) cases and there were no survivors in 24 (21.6%) cases. On the extreme assumption that, had laser surgery not been carried out in these cases, all fetuses would have died, the total fetal loss rate at < 24 weeks' gestation in MCDA twins would have been 13.5%. CONCLUSIONS: The rates of fetal loss at < 24 weeks' gestation, perinatal death at ≥ 24 weeks and preterm birth are higher in MCDA and more so in MCMA twins than in DC twins. In MCDA twins, the rate of fetal loss may have been reduced by endoscopic laser surgery in those that developed early TTTS and/or sFGR. These data would be useful in counseling parents as to the likely outcome of their pregnancy and in defining strategies for surveillance and interventions in the management of the different types of twin pregnancy. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Resultado del embarazo de gemelos con dos fetos vivos a las 11-13 semanas de gestación OBJETIVOS: Informar y comparar el resultado de embarazos de gemelos dicoriales (DC), monocoriales diamnióticos (MCDA) y monocoriales monoamnióticos (MCMA) con dos fetos vivos a las 11-13 semanas de gestación y examinar la repercusión de la cirugía endoscópica con láser para los casos graves del síndrome de transfusión gemelo a gemelo (STGG) y/o la restricción selectiva del crecimiento fetal (RsCF) en el resultado de gemelos MCDA. MÉTODOS: Este estudio fue un análisis retrospectivo de datos recogidos prospectivamente sobre embarazos de gemelos sometidos a un examen ecográfico rutinario a las 11-13 semanas de gestación entre 2002 y 2019. En los embarazos sin anomalías importantes, se comparó la supervivencia general, la pérdida del feto a <24 semanas de gestación, la muerte perinatal a ≥24 semanas, el parto a <37 y <32 semanas, y el peso al nacer <5o percentil entre gemelos DC, MCDA y MCMA. RESULTADOS: La población de estudio fue de 6225 embarazos de gemelos con dos fetos vivos a las 11-13 semanas de gestación sin anomalías importantes y estaba formada por 4896 (78,7%) gemelos DC, 1274 (20,5%) gemelos MCDA y 55 (0,9%) gemelos MCMA. En los gemelos DC, la tasa de pérdida a <24 semanas de gestación, en el total de los fetos fue del 2,3%; esta tasa fue más alta en gemelos MCDA (7,7%; riesgo relativo (RR), 3,258; IC 95%, 2,706-3,923) y mayor aun en gemelos MCMA (21,8%; RR, 9,289; IC 95%, 6,377-13,530). En los gemelos DC, la tasa de muerte perinatal a ≥24 semanas en todos los gemelos que estaban vivos a las 24 semanas fue del 1,0%; esta tasa fue mayor en gemelos MCDA (2,5%; RR, 2,456; IC 95%, 1,779-3,389) y mayor aun en los gemelos MCMA (9,3%; RR, 9,130; IC 95%, 4,584-18,184). En los gemelos DC, la tasa de parto pretérmino a <37 semanas de gestación en embarazos con al menos un gemelo nacido vivo fue del 48,6%; esta tasa fue mayor en gemelos MCDA (88,5%; RR, 1,824; IC 95%, 1,760-1,890) y mayor aun en los gemelos MCMA (100%; RR, 2,060; IC 95%, 2,000-2,121). En los gemelos DC, la tasa de parto pretérmino a <32 semanas de gestación fue del 7,4%; esta tasa fue mayor en gemelos MCDA (14,2%; RR, 1,920; IC 95%, 1,616-2,281) y mayor aun en los gemelos MCMA (26,8%; RR, 3,637; IC 95%, 2,172-6,089). En los embarazos de gemelos DC con al menos un gemelo nacido vivo, la tasa de un recién nacido pequeño para la edad gestacional entre todos los gemelos nacidos vivos fue del 31,2% y en los gemelos MCDA esta tasa fue mayor (37,8%; RR, 1,209; IC 95%, 1,138-1,284); en los gemelos MCMA, la tasa no fue significativamente diferente (33,3%; RR, 1,067; IC 95%, 0,783-1,455). El análisis de Kaplan-Meier mostró una diferencia significativa en la supervivencia de los gemelos MCDA y MCMA, en comparación con los gemelos DC, tanto para el intervalo de 12 a <24 semanas de gestación (prueba logarítmico-ordinal, P<0,0001 para ambos) como para el de ≥24 a 38 semanas (prueba logarítmico-ordinal, P<0,0001 para ambos). La ablación endoscópica con láser de los vasos placentarios comunicantes entre gemelos se llevó a cabo en 127 (10,0%) embarazos de gemelos MCDA para STGG y/o RsCF y, en 111 de ellos, la cirugía se realizó a <24 semanas; en 62 (55,.9%) casos sobrevivieron ambos fetos, en 25 (22,5%) casos sobrevivió uno de los fetos y en 24 (21,6%) casos no hubo sobrevivientes. En la suposición extrema de que, si no se hubiera utilizado la cirugía láser en estos casos, todos los fetos habrían muerto, la tasa de pérdida fetal total a <24 semanas de gestación in gemelos MCDA hubiera sido del 13,5%. CONCLUSIONES: Las tasas de pérdida fetal a <24 semanas de gestación, de muerte perinatal a ≥24 semanas y de parto pretérmino son mayores en gemelos MCDA y más aun en gemelos MCMA que en gemelos DC. En los gemelos MCDA, la tasa de pérdida fetal podría haberse reducido mediante la cirugía endoscópica láser en aquellos que desarrollaron STGG y/o RsCF de forma temprana. Estos datos podrían ser útiles para asesorar a los padres en cuanto al resultado probable de su embarazo y para definir las estrategias de vigilancia e intervenciones en el tratamiento de los diferentes tipos de embarazo de gemelos.

Intertwin discordance in fetal size at 11-13 weeks' gestation and pregnancy outcome.

OBJECTIVE: To investigate the value of intertwin discordance in fetal crown-rump length (CRL) at the 11-13-week scan in the prediction of adverse outcome in dichorionic (DC), monochorionic diamniotic (MCDA) and monochorionic monoamniotic (MCMA) twin pregnancies. METHODS: This was a retrospective analysis of prospectively collected data on twin pregnancies undergoing routine ultrasound examination at 11-13 weeks' gestation between 2002 and 2019. In pregnancies with no major abnormalities, we examined the value of intertwin discordance in fetal CRL in DC, MCDA and MCMA twins in the prediction of fetal loss at < 20 and < 24 weeks' gestation, perinatal death at ≥ 24 weeks, preterm delivery at < 32 and < 37 weeks, birth of at least one small-for-gestational-age (SGA) neonate with birth weight < 5th percentile and intertwin birth-weight discordance of ≥ 20% and ≥ 25%. RESULTS: First, the study population of 6225 twin pregnancies included 4896 (78.7%) DC, 1274 (20.4%) MCDA and 55 (0.9%) MCMA twin pregnancies. Second, median CRL discordance in DC twin pregnancies (3.2%; interquartile range (IQR), 1.4-5.8%) was lower than in MCDA twins (3.6%; IQR, 1.6-6.2%; P = 0.0008), but was not significantly different from that in MCMA twins (2.9%; IQR, 1.2-5.1%; P = 0.269). Third, compared to CRL discordance in DC twin pregnancies with two non-SGA live births at ≥ 37 weeks' gestation, there was significantly larger CRL discordance in both DC and MCDA twin pregnancies complicated by fetal death at < 20 and < 24 weeks' gestation, perinatal death at ≥ 24 weeks, preterm birth at < 32 and < 37 weeks, birth of at least one SGA neonate and birth-weight discordance ≥ 20% and ≥ 25%, and in MCDA twin pregnancies undergoing endoscopic laser surgery. Fourth, the predictive performance of CRL discordance for each adverse pregnancy outcome was poor, with areas under the receiver-operating-characteristics curves ranging from 0.533 to 0.624. However, in both DC and MCDA twin pregnancies with large CRL discordance, there was a high risk of fetal loss. Fifth, in DC twin pregnancies, the overall rate of fetal loss at < 20 weeks' gestation was 1.3% but, in the small subgroup with CRL discordance of ≥ 15%, which constituted 1.9% of the total, the rate increased to 5.3%. Sixth, in MCDA twin pregnancies, the rate of fetal loss or endoscopic laser surgery at < 20 weeks was about 11%, but, in the small subgroups with CRL discordance of ≥ 10%, ≥ 15% and ≥ 20%, which constituted 9%, < 3% and < 1% of the total, the risk was increased to about 32%, 49% and 70%, respectively. Seventh, in MCMA twin pregnancies, there were no significant differences in CRL discordance for any of the adverse outcome measures, but this may be the consequence of the small number of cases in the study population. CONCLUSIONS: In both DC and MCDA twin pregnancies, increased CRL discordance is associated with an increased risk of fetal death at < 20 and < 24 weeks' gestation, perinatal death at ≥ 24 weeks, preterm birth at < 37 and < 32 weeks, birth of at least one SGA neonate and birth-weight discordance ≥ 20% and ≥ 25%, but CRL discordance is a poor screening test for adverse pregnancy outcome. However, in DC twins, CRL discordance of ≥ 15% is associated with an increased risk of fetal loss at < 20 and < 24 weeks' gestation and, in MCDA twins, CRL discordance of ≥ 10%, and more so discordance of ≥ 15% and ≥ 20%, is associated with a very high risk of fetal loss or endoscopic laser surgery at < 20 and < 24 weeks and this information is useful in counseling women and defining the timing for subsequent assessment and possible intervention. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

[Clinical characteristics and outcomes of monochorionic monoamniotic twin pregnancy].

Objective: To investigate the clinical characteristics and outcomes of monochorionic monoamniotic (MCMA) twin pregnancy. Methods: The clinical data of 60 MCMA twin pregnant women who were terminated in Peking University Third Hospital from January 2011 to December 2019 were collected, and the general clinical data, prenatal examination and pregnancy outcomes were analyzed retrospectively. Results: The age of 60 MCMA twin pregnant women was (31.0±4.1) years old, among which 44 cases were primiparas (73%, 44/60) and 16 cases were multiparas (27%, 16/60). Fifty-eight cases were diagnosed as MCMA twin pregnancy prenatally and were confirmed after delivery. Median ultrasonic diagnosis of gestational age was 12 weeks (range: 8-30 weeks). In the 60 MCMA twin pregnancies, 6 cases were conjoined twins, 5 cases were complicated with twin reversed arterial perfusion sequence (TRAPS), and 10 cases were diagnosed as other fetal malformation by prenatal ultrasound examination. Among the 60 MCMA twin pregnant women, 19 cases had spontaneous abortion or induced abortion due to fetal malformation, fetal death or other reasons within 28 weeks of pregnancy, 41 cases entered the perinatal period, a total of 70 newborns survived. The main cause of perinatal fetal or neonatal death was fetal dysplasia. Conclusions: There is a high incidence of fetal abnormality and perinatal mortality in MCMA twin pregnancy. Accurate early diagnosis, enhanced management and monitoring during pregnancy, and individualized treatment are the keys to improve MCMA twin pregnancy outcomes.

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

OBJECTIVE: 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. METHODS: 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 ≥ 37 weeks 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. RESULTS: 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. CONCLUSIONS: 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.

Prevalence, antenatal management and perinatal outcome of monochorionic monoamniotic twin pregnancy: a collaborative multicenter study in England, 2000-2013.

OBJECTIVES: To determine the prevalence of monochorionic monoamniotic (MCMA) twin pregnancy and to describe perinatal outcome and clinical management of these pregnancies. METHODS: In this multicenter cohort study, the prevalence of MCMA twinning was estimated using population-based data on MCMA twin pregnancies, collected between 2000 and 2013 from 11 Northern Survey of Twin and Multiple Pregnancy (NorSTAMP) maternity units. Pregnancy outcome at < 24 weeks' gestation, antenatal parameters and perinatal outcome (from ≥ 24 weeks to the first 28 days of age) were analyzed using combined data on pregnancies confirmed to be MCMA from NorSTAMP and the Southwest Thames Region of London Obstetric Research Collaborative (STORK) multiple pregnancy cohort for 2000-2013. RESULTS: The estimated total prevalence of MCMA twin pregnancies in the North of England region was 8.2 per 1000 twin pregnancies (59/7170), and the birth prevalence was 0.08 per 1000 pregnancies overall (singleton and multiple). Using combined data from NorSTAMP and STORK, the rate of fetal death (at < 24 weeks' gestation), including terminations of pregnancy and selective feticide, was 31.8% (54/170); the overall perinatal mortality rate was 14.7% (17/116), ranging from 69.2% at < 30 weeks to 4.5% at ≥ 33 weeks' gestation. MCMA twins that survived in utero beyond 24 weeks were delivered, usually by Cesarean section, at a median of 33 (interquartile range, 32-34) weeks of gestation. CONCLUSIONS: In MCMA twins surviving beyond 24 weeks of gestation, there was a higher survival rate compared with in previous decades, presumably due to early diagnosis, close surveillance and elective birth around 32-34 weeks of gestation. High perinatal mortality at early gestations was attributed mainly to extreme prematurity due to preterm spontaneous labor. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Outcomes of monoamniotic twin pregnancies managed primarily in outpatient care-a Danish multicenter study.

INTRODUCTION: Monoamniotic twin pregnancies are high-risk pregnancies, and management by inpatient or frequent outpatient care is recommended. We report the outcomes of a national cohort of monoamniotic twin pregnancies managed primarily as outpatients. MATERIAL AND METHODS: We prospectively analyzed the recorded data from the Danish Fetal Medicine Database, local databases, and medical records of all monoamniotic twin pregnancies diagnosed at the first trimester scan or later, and managed at the six major fetal medicine centers in Denmark over a 10-year period. RESULTS: Sixty-one monoamniotic twin pregnancies were included. Thirteen pregnancies were terminated early. Of the remaining 48 pregnancies with a normal first trimester scan, there were 36 fetal losses (25 spontaneous miscarriages <22+0  weeks, 3 late terminations and 8 intrauterine deaths >22 weeks) and 60 liveborn children (62.5%), all of whom were delivered by cesarean delivery at a median gestational age of 33+0  weeks. Three children had minor malformations and there was 1 pregnancy with twin-to-twin transfusion syndrome. After 26+0  weeks, 78.8% were managed as outpatients. Intrauterine death occurred in 3.8% of outpatients and in 28.6% of inpatients (admitted due to complications). At weeks 32, 33 and 34, the prospective risk of intrauterine death was 6.9%, 4.2% and 5.9%, respectively. CONCLUSION: In this nationwide, unselected population, only 62.5% of fetuses with a normal first trimester scan were born alive. In contrast, the mortality was 3.8% after 26 weeks among the 78.8% of the cohort that was managed as outpatients. More knowledge is still needed to predict which pregnancies are at the highest risk of intrauterine death.