Unilateral hydronephrosis with congenital absence of contralateral kidney in children. Report of six cases and review of literature.

The case histories of six children with absence of functioning renal parenchyma on one side and dilatation of the contralateral pelvis are reviewed. The hydronephrosis was obstructive in two cases. In the others no cause could be found. The development of this combination of renal malformations is discussed against an embryologic background.