Pregnancy outcome of monochorionic twins: does amnionicity matter?

OBJECTIVE: To compare the fetal loss rate of monochorionic (MC) twin pregnancies according to their amnionicity. METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Detection of foetal growth restriction using third trimester ultrasound.

Foetal growth restriction is an important contributor to perinatal mortality, being responsible for up to 50% of stillbirths. Optimal prevention and accurate detection enabling timely intervention remain elusive, particularly in presumed low-risk pregnancy. Third trimester ultrasound seems a logical solution, but systematic review of evidence from randomised trials has shown that third trimester ultrasound does not have a significant impact on perinatal mortality but may increase interventions such as caesarean delivery. However, the evidence is difficult to interpret in the context of current obstetric practice as the evolution of ultrasound technology and rapid assimilation of newer techniques has resulted in questionable validity of the findings. If third trimester ultrasound were introduced routinely, there is a need to decide the optimal timing and number of examinations and what ultrasound parameters should be used to identify the foetus at risk.