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 is limited. The objective of this study is 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 outcome. 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% versus 31%, p<0.001) and a lower gestational age at birth (30.7 versus 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 two 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 one in five cases. Intertwin membrane perforation was associated with a lower gestational age at birth and a higher rate of severe cerebral injury in surviving neonates.