Latrogenic twin anemia: polycythemia sequence post-amnioreduction in twin-twin transfusion syndrome

We present a case of Iatrogenic twin anemia–polycythemia sequence (TAPS) post-amnioreduction in twin-twin transfusion syndrome at 32 gestational weeks. Slight middle cerebral artery (MCA) peak systolic velocity (PSV) discrepancy was present 3 days after the amnioreduction, with MCA PSV around 1.5 MoM of the doner and 1.0 MoM of the recipient. Eighteen days after the amnioreduction, though MCA PSV remained stable, placental dichotomy, starry-sky liver of the recipient and small amount of right pleural effusion of donor were noted. TAPS was diagnosed and postnatal examination of the twins and the placenta confirmed it. We conjectured that the decompression of the placenta after the sudden reduction of amniotic fluid volume may cause the patency of the tiny anastomoses, resulting in the TAPS.