Twin-twin transfusion syndrome: sonographic findings.

Twin-twin transfusion syndrome (intrauterine parabiotic syndrome) is a potentially serious complication of monochorionic twinning. The frequency of fetal and neonatal death and perinatal morbidity is significantly higher than that in twin pregnancies uncomplicated by the syndrome. The authors present sonographic findings in ten cases of twin-twin transfusion syndrome proved by means of pathologic examination of the placenta and/or laboratory findings. The cases all involved diamniotic twins and covered a broad range of severity. Discordant fetal size and differing amniotic fluid volume in the two sacs were the most common findings. In more severe cases, hydrops of the recipient fetus and/or a "stuck" donor fetus was seen. Intrauterine death of one or both twins was observed in four cases. Familiarity with the sonographic patterns of the twin-twin transfusion syndrome can allow one to suggest the diagnosis in utero so that appropriate management can be undertaken.