Antenatal Workup of Early Megacystis and Selection of Candidates for Fetal Therapy

Objective: To investigate the best criteria for discriminating fetuses with isolated posterior urethral valves from those theoretically not eligible for fetal treatment because of complex megacystis, high chance of spontaneous resolution, and urethral atresia. Methods: A retrospective national study was conducted in fetuses with megacystis detected before 17 weeks’ gestation (early megacystis). Results: In total, 142 cases with fetal megacystis were included in the study: 52 with lower urinary tract obstruction, 29 with normal micturition at birth, and 61 with miscellaneous syndromal associations, chromosomal and multiple structural abnormalities (complex megacystis). Only a nuchal translucency > 95th centile, and not a longitudinal bladder diameter ≤15 mm (p = 0.24), significantly increased the risk of complex megacystis (p 12 mm, and without ultrasound evidence of umbilical cord cysts