The role of superficial anastomoses in the survival of fetuses with twin-twin transfusion syndrome after fetoscopic laser photocoagulation is unknown. This study aimed to evaluate how superficial anastomoses affect the circulatory dynamics of both fetuses with twin-twin transfusion syndrome using ductus venous Doppler waveforms. We included all twin-twin transfusion syndrome (TTTS) patients who underwent fetoscopic laser photocoagulation in our institution from 2006 to 2019; fetal demise cases after fetoscopic laser photocoagulation were excluded. We recorded ductus venous Doppler waveforms on the same day or one day before fetoscopic laser photocoagulation and one day after fetoscopic laser photocoagulation and measured the ductus venous pulsatility index and velocity ratios. We compared these z-scores of donor and recipient twins between a group without superficial anastomoses and the groups with arterio-arterial or veno-venous anastomoses. A total of 115 surviving TTTS placentas after fetoscopic laser photocoagulation were analyzed. The ductus venous pulsatility index and all ratios were better in recipient twins with arterio-arterial anastomoses than in those without. The a-wave-related ratios were better in recipient twins with veno-venous anastomoses than in those without. Superficial anastomoses reduced the blood volume and arterio-arterial anastomoses protected the diastolic cardiac function in recipient twin-twin transfusion syndrome twins before fetoscopic laser photocoagulation. Superficial anastomoses in TTTS equilibrate blood pressure between donor and recipient twins.

Twin reversed arterial perfusion (TRAP) sequence is a rare anomaly in 1% of monochorionic twin pregnancies. Few TRAP sequence cases have a rudimentary heart with cardiac motion in the acardiac twins. Herein, we investigated the venous Doppler waveform in two cases of TRAP sequence with a rudimentary heart with cardiac motion in the acardiac twin. Although both cases had veno-venous anastomoses, the venous Doppler waveforms of the umbilical vein differed. A comparison of the characteristics of the cases indicated that the existence of a ductus venosus, or greater heart pulse power, in the acardiac twin might impact the venous Doppler waveform in the pump twin.