Diamniotic twin gestation discordant for renal dysplasia and oligohydramnios.

Severe oligohydramnios and renal dysplasia were detected in one of diamniotic, monochorionic twins at 19 weeks' gestation. At birth (37 weeks), the affected twin had only minimal extrarenal Potter's features and mild pulmonary hypoplasia, despite severe renal dysplasia due to posterior urethral valves. The effects of virtual absence of amniotic fluid during the latter half of gestation from bilateral renal dysplasia were ameliorated by the presence of a normal co-twin and its normal amniotic fluid levels, even though the affected twin did not share the same amniotic fluid.