Ductus venosus blood flow evaluation at 11–14 weeks in the anticipation of twin-twin transfusion syndrome in monochorionic twin pregnancies

Abstract

Twin–twin transfusion syndrome (TTTS) is a serious complication, occurring in about 15% of monochorionic twin pregnancies. Strong evidence suggests that increased fetal nuchal translucency thickness (NT) in one of the monochorionic twins is highly predictive of TTTS. One of the most plausible mechanisms for increased NT is heart failure, which can be indirectly manifested by abnormal blood flow in the ductus venosus. We present 20 cases of monochorionic twin pregnancies in which both NT thickness and ductus venosus blood flow evaluation were performed at 11–14 weeks. Whenever both fetuses showed discrepant NT, and abnormal ductal flow was found in the fetus with increased NT, TTTS eventually developed. In none of the twins displaying similar NT measurements, and in those with discrepant NT but normal flow in the ductus venosus of both fetuses, was the progression to TTTS observed. In the two cases that developed TTTS, fetoscopic laser coagulation of the vascular anastomoses was successfully carried out at 18 weeks, and normalization of the venous return was recorded. Increased NT and abnormal flow in the ductus venosus in monochorionic twins may be early manifestations of hemodynamic imbalance between donor and recipient The combined evaluation of both parameters in monochorionic twin pregnancies could be an effective screening method.