Posterior urethral valves: how the study of fetal micturition can help to reach the diagnosis?

What's Already Known about this Topic? Accurate prenatal diagnosis of posterior urethral valves remains challenging in male fetuses with megacystis, thick bladder and/or bilateral hydronephrosis. It is now established that the keyhole sign is not a reliable predictor of the diagnosis of PUV in these situations. What does this Study Add? The sonographic study of fetal micturition may be more accurate for the diagnosis of posterior urethral valves in male fetuses with fetal megacystis, thick bladder or uretero hydronephrosis, regardless of the presence or not of the keyhole sign. Investigation of fetal micturition improves the diagnosis by showing a dilated posterior urethra, modelled on the images of postnatal voiding cystourethrography.