Normal pulmonary function in a monoamniotic twin discordant for bilateral renal agenesis: report and review.

Renal agenesis and obstructive urinary tract anomalies causing oligohydramnios usually result in pulmonary hypoplasia. We report on the first female monoamniotic twin born with a combination of bilateral renal agenesis, agenesis of the urinary collecting system, absent external genitalia, anal atresia and single umbilical artery, compatible with VATER association but with normal pulmonary function. The infant had none of the manifestations of Potter sequence, in particular the facial changes and pulmonary hypoplasia typically associated with bilateral renal a/dysgenesis. The monoamniotic cotwin had normal renal function, such that sufficient amniotic fluid volume was maintained. This patient emphasizes the importance of adequate amniotic fluid volume for normal pulmonary development. The possible underestimation of genital malformations in the VATER association should be considered. Also noteworthy is the rare absence of external genitalia.