Identification of arterio-venous anastomoses in vivo in monochorionic twinpregnancies: preliminary report

Objective To determine whether it is possible to identify in vivo placental arterio-venous anastomoses (AVAs) by color Doppler flow mapping. Methods Three monochorionic twin pregnancies (one with and two without twin -to-twin transfusion syndrome) underwent placental mapping by color Doppler ultrasound. Placental vessels along the chorionic plate were recorded toge ther with the direction of blood flow and their location in relation to the cord insertions and to superficial arterio-arterial anastomoses. Suggestiv e AVAs were mapped topographically and results were compared with the findi ngs of formal postnatal placental injection studies. Results An AVA was identified in each of the three cases. Injection studies showed multiple AVAs. Each antenatally identified AVA was confirmed at pla cental injection study. Their placental location correlated to other landma rks as predicted by ultrasound. Conclusions This preliminary report demonstrates that AVAs can be identifie d using color Doppler ultrasound. This may facilitate planning for highly s elective ablation of AVAs, and shorter procedure times. Formal studies are now indicated to determine the accuracy of this technique.