Erythroblastosis of the Donor Twin of Twin Anemia-Polycythemia Sequence.

Twin anemia-polycythemia sequence (TAPS) is a group of disorders in monochorionic twins characterized by a large intertwin hemoglobin difference without amniotic fluid discordance. Reticulocyte count is used to diagnose this condition, but little is known about the role of erythroblasts, which are the prior stage of reticulocytes. In the present case of TAPS, the 25-yr-old Japanese mother showed no signs of oligohydramnios or polyhydramnios throughout gestation.