Postnatal vesico-ureteral reflux in a boy with urinary bladder dysfunction as the only prenatal sonographic sign.

An antenatal ultrasonographic examination of a male fetus at 31, 33 and 36 weeks' gestation revealed grossly abnormal bladder function. The bladder cycle length, residual volumes and the degree of distention all markedly deviated from normal, although hydronephrosis which is indicative of vesico-ureteral reflux could not be detected. Furthermore, postnatally no anatomical urethral obstruction was found to explain the high bladder volumes. Postnatal investigation revealed bilateral reflux and bladder dysfunction with detrusor instability, a reduced bladder capacity and a high voiding pressure similar to that observed in boys with anatomic obstruction of the urethra and/or posterior urethral valves. These findings add to the controversy concerning the genesis of vesico-ureteral reflux and have implications for the prenatal assessment of bladder function in cases of suspected vesico-ureteral reflux.