Oligohydramnios sequence (Potter's syndrome): case clustering in northeastern Tennessee.

The oligohydramnios sequence (OS) is manifest in newborns when prolonged oligohydramnios has been present during pregnancy. The most important signs are an infant small for gestational age, with wrinkled skin, Potter facies, compression deformities of the limbs, and respiratory distress caused by pulmonary hypoplasia. The recurrence rate of kidney conditions implicated in OS depends on the severity of the condition in the previously affected sib. While absent or encysted kidneys (Potter types II and IV) are incompatible with life, chronic leakage of amniotic fluid may result in a viable infant who shows some signs of OS. The usual incidence of absent or encysted kidneys is 1 per 6,250 births. This rate was exceeded recently in northeastern Tennessee, in a clustering of cases for which no environmental causes are evident.