Monoamniotic twin pregnancy

Abstract

Key contentr Monoamniotic twins are believed to account for 1-5% of all monozygotic conceptions, with an estimated annual incidence of 30-150 pregnancies in the UK. r High perinatal loss rates in monoamniotic twins have been attributed mainly to umbilical cord entanglement, inter-twin transfusion syndrome, discordant fetal abnormality or fetal growth restriction. r Management of monoamniotic twin pregnancy is aimed at preventing antenatal fetal death and optimising timing of delivery. r Despite the paucity of robust data on the incidence and causes of perinatal loss, elective delivery at 32-34 weeks of gestation has been proposed. r Most obstetric units use caesarean birth as the preferred mode of delivery for monoamniotic twins to prevent intrapartum cord complications. Learning objectivesr To understand the aetiology, incidence and diagnosis of monoamnionicity. r To be able to identify the type and prevalence of complications in monoamniotic twins. r To be aware of the current evidence on the antenatal management and optimal timing of delivery of monoamniotic twin pregnancy. Ethical issuesr Can we justify elective preterm delivery and its subsequent complications without a robust evidence base demonstrating a reduction in perinatal morbidity and mortality?

Inpatient vs outpatient management and timing of delivery of uncomplicated monochorionic monoamniotic twin pregnancy: the MONOMONO study

“…Monochorionic monoamniotic twinning accounts for about 1–2% of monozygotic twin pregnancies worldwide. Monoamniotic twins are at increased risk of perinatal complications compared with monochorionic diamniotic or dichorionic twin pregnancies. Perinatal mortality is reported to be high in monoamniotic twins, primarily owing to cord entanglement.…”

“…Monoamniotic twins are at increased risk of perinatal complications compared with monochorionic diamniotic or dichorionic twin pregnancies. Perinatal mortality is reported to be high in monoamniotic twins, primarily owing to cord entanglement. Early‐ and mid‐pregnancy loss before 26 weeks' gestation seems to be correlated mainly with the incidence of twin reversed arterial perfusion (TRAP) sequence, conjoined twins and major congenital anomalies, the rate of these complications being as high as 60% in studies evaluating high‐risk referred populations.…”

“…Perinatal mortality is reported to be high in monoamniotic twins, primarily owing to cord entanglement. Early‐ and mid‐pregnancy loss before 26 weeks' gestation seems to be correlated mainly with the incidence of twin reversed arterial perfusion (TRAP) sequence, conjoined twins and major congenital anomalies, the rate of these complications being as high as 60% in studies evaluating high‐risk referred populations. Regarding pregnancy loss after 26 weeks, the largest review of monoamniotic twins, including 60 studies and 133 non‐conjoined monoamniotic twin pregnancies, reported a non‐anomalous perinatal mortality rate of about 20%, with a significant rise in mortality after 32 weeks' gestation.…”

“…Regarding pregnancy loss after 26 weeks, the largest review of monoamniotic twins, including 60 studies and 133 non‐conjoined monoamniotic twin pregnancies, reported a non‐anomalous perinatal mortality rate of about 20%, with a significant rise in mortality after 32 weeks' gestation. These data are often used to justify planned preterm delivery from 32 weeks in otherwise uncomplicated monoamniotic twins; however, robust data on which a decision about the timing of delivery can be based are missing.…”

Weight discordance and perinatal mortality in monoamniotic twin pregnancy: analysis of MONOMONO, NorSTAMP and STORK multiple‐pregnancy cohorts

“…Monochorionic monoamniotic (MCMA) twin pregnancies are at increased risk of perinatal mortality and morbidity compared with monochorionic diamniotic and dichorionic twin pregnancies, especially as a consequence of preterm birth, fetal anomalies and acute transfusion events 2,3 . These risks have been associated with a loss rate as high as 70% in older literature [3][4][5][6][7] . Recently, several multinational studies showed a substantially improved chance of perinatal survival, with mortality rates ranging from 10% to 30% [8][9][10][11] , although the optimal type of monitoring has still to be defined 7 .…”