Hydronephrosis in renal ectopia: incidence, etiology and significance.

The incidence, cause and significance of hydronephrosis in patients with renal ectopia are unknown. Therefore, we conducted a retrospective review of 77 patients with 82 ectopic kidneys. Of 82 kidneys 46 (56%) had hydronephrosis. Dilatation of the renal pelvis was the result of primary ureteropelvic or ureterovesical obstruction in 52%, grade 3, 4 or 5 vesicoureteral reflux in 26% and extrarenal collecting systems with malrotation that produced apparent ureteropelvic junction obstruction in 22%. Surgery was performed in 41 patients, including primary nephrectomy in 18, ureteral reimplantation in 14 and ureteropelvic junction repair in 8. Hydronephrosis was present in 15 of 58 contralateral nonectopic kidneys, and 11 required surgery mostly for vesicoureteral reflux. Solitary ectopic kidneys with no associated obstruction or reflux demonstrated normal renal function. Our data indicate that the prognosis in renal ectopia relates directly to the associated urological disease and timely surgical intervention, not to ectopia alone.