The use of amniotic fluid discordance in the early second trimester to predict severe twin-twin transfusion syndrome.

INTRODUCTION The appropriate effectiveness of inter-twin amniotic fluid discordance (AFD) in the early second trimester for the prediction of severe twin-twin transfusion syndrome (TTTS) was evaluated. MATERIALS AND METHODS The largest AFD between 16 and 18 weeks' gestation was analyzed in correlation with TTTS development defined by polyhydramnios with a maximum vertical pocket (MVP) ≥8 cm combined with oligohydramnios with a MVP ≤2 cm using the receiver operating characteristics curve. All pregnancies were stratified according to an AFD cutoff, and perinatal outcomes were compared between two groups. RESULTS A total of 223 twin monochorionic pregnancies met the inclusion criteria and 20 patients (8.9%) developed TTTS. An AFD ≥4 cm was calculated to be the optimal point of demarcation to predict subsequent TTTS. The sensitivity and specificity of this AFD cutoff for the development of TTTS were 70 and 97%, respectively. An AFD ≥4 cm was associated with a significantly increased risk of the development of TTTS (70 vs. 2.9%; p < 0.01). Those pregnancies with AFD tended to deliver at an earlier gestational age and were also significantly associated with intrauterine fetal deaths. DISCUSSION The AFD between monochorionic diamniotic twins in the early second trimester may be useful for the prediction of severe TTTS development.