A case of twin anemia-polycythemia sequence with an arterio-arterial anastomosis complicated by selective intrauterine growth restriction

Abstract

Twin anemia-polycythemia sequence (TAPS) is characterized by the presence of a small number of minuscule arterio-venous (AV) anastomoses on the placental surface, and arterio-arterial (AA) anastomoses are hardly observed. We encountered a case of TAPS with not only two AV anastomoses but also a single AA anastomosis on the placenta. In this case, the diagnosis of selective intrauterine growth restriction (IUGR) was made at 34 weeks of gestation, and the diagnosis of TAPS was made at 35 weeks of gestation by detecting an abnormal middle cerebral artery peak systolic velocity on Doppler ultrasound. A non-stress test showed recurrent late decelerations of the anemic twin; thus, an emergent cesarean delivery was performed. At the time of birth, the larger twin was plethoric and the hemoglobin level was 21.9 g/dl, whereas the smaller twin was pale and the hemoglobin level was 4.2 g/dl. AA anastomoses are believed to play a role in compensating the blood flow through the AV anastomoses between twins; however, our experience showed that TAPS can occur even if an AA anastomosis exists.