Clinical consequences of twin-to-twin transfusion.

Twin-to-twin transfusion (TTT) is a complication of monochorionic twins that may result in high mortality and morbidity. To better understand pathophysiology in TTT and the consequences for affected fetuses and neonates, we describe the clinical features of 19 consecutive pregnancies complicated by TTT over 5 years. The diagnosis was made based on the findings of polyhydramnios-oligohydramnios sequence with weight discordance judged by obstetrical sonogram in monochorionic twins. Serial amnioreductions were performed as the sole modality of therapeutic intervention when indicated. The obstetrical diagnosis of TTT was first made at a median gestational age of 26 weeks (range 20-35 weeks). Median age of delivery was 30 weeks (range 26-36 weeks). Thirty-three babies of the 19 pairs of twins were born alive, but only 21 of them lived beyond 28 days of life. Fifteen pairs of twins with TTT had weight discordance greater than 20%, but only one pair showed initial hemoglobin difference greater than 5 g/dl. Newborn infants with TTT were at risk for development of renal insufficiency, periventricular leukomalacia, and necrotizing enterocolitis. Intrauterine fetal demise of one twin and severe anemia (hemoglobin <10 g/dl) at birth were poor prognostic factors. Recent advances in perinatal care improves pregnancy outcome of TTT; however, surviving neonates are still at risk for morbidities arising from hemodynamic aberrations.