A monochorionic diamniotic twin pregnancy complicated by umbilical cord entanglement after a spontaneous septostomy: a case report

Abstract Background: Umbilical cord entanglement is typically associated with monochorionic monoamniotic (MCMA) twin pregnancies and is very rare in monochorionic diamniotic (MCDA) twins unless a spontaneous septostomy occurs. This case is unusual for a fatal outcome from cord entanglement in a pregnancy previously confirmed as MCDA, with septostomy only identified after delivery. It highlights the need for continued vigilance even when intertwin membranes have been visualized earlier in gestation. Case Presentation: A 31 year old Ethiopian woman, Gravida 3 Para 2, was followed at Abebech Gobena Referral Hospital, Ethiopia. A detailed fetal scan at 26 weeks and 5 days confirmed an MCDA twin pregnancy with normal findings for both fetuses. She subsequently received biweekly antenatal evaluations to monitor growth, amniotic fluid, and uterine artery Dopplers, all of which remained unremarkable until 36 weeks. Elective delivery was planned at 37 weeks. At 36 weeks and 6 days, she presented with two hours of pushing down pain and reported decreased fetal movement for three days. Ultrasound revealed intrauterine fetal demise of both twins. She delivered vaginally, and postpartum examination demonstrated umbilical cord entanglement and disruption of the intertwin membrane, consistent with spontaneous septostomy. Conclusion: This rare case emphasizes the importance of maintaining clinical suspicion for spontaneous septostomy in MCDA pregnancies, as the resulting functionally monoamniotic environment can lead to catastrophic complications such as cord entanglement. Continued surveillance and heightened awareness are essential to facilitate timely intervention and reduce fetal morbidity and mortality in these high risk scenarios.