Crossed renal ectopia without fusion associated with hydronephrosis in an infant.

The incidence of crossed "fused" renal ectopia has been reported at 1 in 7,500 autopsies, an incidence approximately ten times more frequent than crossed renal ectopia without fusion. Most cases remain asymptomatic and are incidentally encountered on autopsy or during routine workup for unrelated disorders. We herein report a case of ureteropelvic junction obstruction secondary to a high ureteral insertion in the pelvis of a crossed unfused ectopic kidney.