Early prediction of severe twin-to-twin transfusion syndrome

This extended series of 303 monochorionic twin pregnancies examined at 10-1 4 weeks gestation explores the possible association of increased fetal nuch al translucency thickness (NT) in the early prediction of severe twin-to-tw in transfusion syndrome (TTS), Of 303 pregnancies, there were 16 in which a t least one fetus was structurally or chromosomally abnormal and in the rem aining 287 ongoing pregnancies there were 43 (15%) which developed severe T TS, The median fetal NT was 1.0 multiples of the median (MOM) and NT was >9 5th centile in 47 (8.2%) fetuses and in at least one fetus in 37 (12.9%) pr egnancies. The prevalence of increased NT in the pregnancies that developed TTS [17.4% (n = 15) of fetuses and 28% (n = 12) of pregnancies] was signif icantly higher than in the non-TTS group [6.6% (n = 32) and 10.2% (n = 25) respectively; Z = -3.4, P < 0.001 and Z = 3.2, P < 0.001 respectively],, li kelihood ratio of increased fetal NT for prediction of TTS = 3.5 [95% confi dence interval (CI) 1.9-6.2], In 153 of the pregnancies, an ultrasound exam ination was also performed at 15-17 weeks gestation and intertwin membrane folding was seen in 49 (32%) cases; 21 of these (43%) subsequently develope d TTS compared to two (1.9%) of the 104 pregnancies without membrane foldin g (Z = 6.6, P < 0.001), likelihood ratio of membrane folding for prediction of TTS = 4.2 (95% CI 3.0-6.0).