Prognostic factors in severe twin-twin transfusion syndrome treated by endoscopic laser surgery

Objective The nim of this study was to investigate clinical and sonographic parameters, in particular Doppler blood potu measurements, in severe secon d-trimester twin-twin transfusion syndrome before and after endoscopic lase r coagulation of the placental vascular anastomoses, to correlate these dat a with fetal outcome and to determine whether fetal blood flow, measurement s could help to estimate the probability of fetal survival. Methods In 121 cases of severe twin-twin transfusion syndrome examined betw een 17 and 26 weeks of gestation,, the following investigations were perfor med: fetal biometry, placental location, deepest pool of amniotic fluid, ec hocardiography and Doppler sonography of the umbilical arteries nod the duc tus venosus of both twins before and after fetoscopic laser ablation of the placental anastomoses. Results The overall survival rate was 64% (156/242). Both fetuses survived in 48% (58/121) and one fetus survived in 33% (40/121), resulting in 81% (9 8/121) of pregnancies with at least one survivor. Gestational age at the ti me of the procedure and placental location had ilo significant influence on fetal survival. The amniotic fluid volume drained after laser coagulation correlated significantly (p = 0.038) with the risk of miscarriage or extrem ely premature delivery within 4 weeks of the procedure. Intertwin discrepan cy in abdominal circumference showed a significant negative correlation (p = 0.004) with the probability for survival of donor fetuses. Before the pro cedure, 29% (23/121) of donor twins and 5% (6/121) of recipient twins showe d absent or reversed end-diastolic flow ill the umbilical artery (p = 0.001 ). This finding had no significant influence on the survival rate of donors . An increase of waveform indices in the umbilical artery 1 day after the p rocedure compared to immediately after the procedure correlated significant ly with a lower probability for survival of donors (p = 0.0042) and recipie nts (p = 0.018). Before the procedure, 37% (45/121) of recipient twins and 9% (10/113) of donor twins showed absent or reversed flow during atrial con traction in the ductus venosus (p < 0.0001). This finding had a significant negative influence on the survival rate of recipient fetuses (p = 0.02). F urthermore, an increase of waveform indices in the ductus venosus 1 day aft er the procedure compared to immediately after the procedure correlated sig nificantly with a lower probability of survival in recipients (p = 0.005). Conclusions Fetoscopic laser coagulation of the placental vascular anastomo ses in severe mid-trimester twin-twin transfusion is a potentially correcti ve and effective, minimally invasive procedure. Doppler investigation of th e umbilical and fetal circulations provides important information on the fe tal condition, prognosis and therapeutic effects of the intervention. Signs of congestive heart failure in the recipient may reduce the probability of survival, whereas increased placental resistance in the donor before the p rocedure is not necessarily associated with a reduction in the probability of survival after laser coagulation.