Hydropic Placenta as a First Manifestation of Twin-Twin Transfusion in a Monochorionic Diamniotic Twin Pregnancy

Monochorionic twin pregnancies are at a 10% to 1.5% risk of developing twin-twin transfusion syndrome (TTTS).(1) Monitoring such pregnancies is aimed at evaluating the fetal condition by measuring the amount of amniotic fluid, Doppler parameters, and fetal growth. Twin-twin transfusion syndrome may be staged by the classification of Quintero et al(2) based on sonographic criteria. However, monochorionic twin pregnancies without the characteristic intertwin discordance in amniotic fluid volumes may still be affected by chronic intertwin transfusion, as reported by Lopriore et al.(3) They reported cases with large differences in fetal or neonatal hemoglobin levels in the absence of the twin oligopolyhydramnios sequence and named this unusual condition twin anemia-polycythemia sequence (TAPS). We report a case in which a thickened placenta of one of the cotwins was an early marker for TAPS, before the occurrence of any of the criteria of Quintero et al(2) for TTTS. To our knowledge, a difference in placental thickness and echogenicity as an early sign of TTTS has not been reported before. A MEDLINE search (English language, 1966-2008, search terms "twin to twin transfusion," "placenta," "edema," and "thickened") revealed no other published cases of hydropic placentas in the absence of fetal hydrops in monochorionic twin pregnancies