EP10.07: Feasibility of fetoscopic laser photocoagulation for Twin–twin transfusion syndrome with fairly close cord insertion sites of the twins

Fetoscopic laser photocoagulation (FLP) is thought to be technically impossible for cases of Twin–twin transfusion syndrome (TTTS) when the cord insertion sites (CIs) of the twins were fairly close. The aim of the case series is to evaluate the feasibility of FLP in cases with close CIs. The indication of FLP was TTTS both with oligohydramnios in the donor twin and polyhydramnios in the recipient twin, basically less than 26 weeks of gestation. Close CIs was defined if the distance between each CI was less than 2cm by preoperative ultrasonography with colour Doppler imaging. Among candidates for FLP for TTTS from October, 2010 to February, 2024, medical chart of each case who met the definition of close CIs, was reviewed retrospectively. Fetoscopic findings, operability of FLP, neonatal outcomes in cases after FLP and placental findings were noted. Over this time period, 408 cases with TTTS underwent FLP. For the same time period, 8 cases with TTTS, who were suspected of close CIs, were candidate for the surgery. Seven of them underwent fetoscopy at a median of 21(17-25) weeks of gestation, with the consent of the patients. In 3 cases, fetoscopy revealed that CIs formed the V-shaped common part in the umbilical cord of the twins near the surface of the placenta and all chorionic vessels were shared by the twins. Therefore, they were considered inoperable and just amnioreduction was performed at fetoscopy. For another 4 cases, ablation of placental vascular anastomoses using Solomon method subsequent to fetoscopic identification of the vascular equator could be accomplished. As neonatal outcomes of the cases after FLP, two resulted in both alive, while one survived in the remaining two. No surviving infants were diagnosed as neurological abnormality. Gross inspection with colour-dye injection for placentas could not reveal residual vascular anastomoses. The feasibility of FLP for TTTS suspected of fairly close CIs could be determined via fetoscopy, not just ultrasonography.