Fetoscopic laser coagulation in 1020 pregnancies with twin-twin transfusion syndrome demonstrates improvement in double-twin survival rate

Objective To investigate the growing experience and learning curve of fetoscopic laser coagulation of the placental vascular anastomoses in severe mid-trimester twin-twin transfusion syndrome (TTTS) and its influence on perinatal outcome in a single-center setting. Methods Between January 1995 and March 2013 we performed laser therapy in 1020 consecutive pregnancies with TTTS between 15.1 and 27.4weeks' gestation. We compared perinatal outcome in blocks of five sequential groups of 200 cases, taking into account several covariates in order to adjust for case mix and to demonstrate learning curves and success rates. Results The percentage of pregnancies with survival of both fetuses increased from 50.0% (n=100) in the first 200 cases to 69.5% (n=153) in the last 220 cases (P=0.018 for trend) and the overall survival rate for both fetuses in the complete series of 1019 cases with known outcome was 63.3% (n=645). The survival rate of at least one fetus increased from 80.5% (161/200) in the first group to 91.8% (202/220) in the last group (P=0.072 for trend) and the overall survival rate of at least one fetus in the complete series was 86.7% (883/1019). In the total population, the mean gestational age at delivery of pregnancies with at least one liveborn neonate was 33.7 +/- 3.2weeks, with a mean interval of 12.9 +/- 4.0weeks between intervention and delivery. Among the first two groups, 124 pregnancies had anterior placentae and were treated with a 0 degrees fetoscope. These cases had the poorest overall outcome, with a double-twin survival rate of 44.4% (55/124), which increased to 65.1% (207/318; P=0.001) after the introduction of a 30 degrees fetoscope for cases with anterior placenta. The success rate for double-twin survival reached a plateau of 69% at 600 procedures, a rate equalled by a new operator who was trained hands-on and performed 174 of the last 400 procedures. Conclusions We report the largest single-center experience of laser coagulation in TTTS. We observed a continuous increase in double-twin survival rate owing to the growing experience based on the learning curve and refinements in fetoscopic instruments and techniques. These data provide strong arguments for the centralization of minimally invasive intrauterine surgery in specialized high-volume centers. Copyright (C) 2017 ISUOG. Published by John Wiley & Sons Ltd.