Long-term followup of prenatally detected severe bilateral newborn hydronephrosis initially managed nonoperatively.

PURPOSE: We determine the outcome of severe bilateral primary ureteropelvic junction type hydronephrosis detected prenatally and managed postnatally with an initially nonoperative protocol.
MATERIALS AND METHODS: A total of 19 newborns (38 kidneys) with prenatally diagnosed primary grade 3 to 4 bilateral hydronephrosis were followed nonoperatively for a mean of 54 months (range 14 to 187). If urinary obstruction with evidence of renal deterioration (decreased differential function and/or progressive hydronephrosis) occurred pyeloplasty was performed.
RESULTS: Pyeloplasty was required in 13 kidneys (35%) in 9 patients (bilateral 4, unilateral 5). Age at pyeloplasty ranged from 2 to 22 months (mean 6.5) in 12 patients and 64 months in 1. The remaining 25 kidneys were followed nonoperatively (bilateral 20, unilateral 5). At last followup the Society for Fetal Urology grade of hydronephrosis in kidneys followed nonoperatively was 0 to 2 in 21 and 3 in 4, compared to 0 to 2 in 9 and Society for Fetal Urology 3 in 4 kidneys treated with pyeloplasty. Mean followup required for the most severely hydronephrotic kidney to achieve maximum ultrasound improvement was 10 months (range 3 to 34) for kidneys followed nonoperatively and 14 months (4-31) for kidneys after pyeloplasty. Differential renal function was measured in each kidney pair and compared using the difference in percent function between the 2 kidneys. In the nonoperative group mean initial difference in percent function was 8% (range 6% to 20%) and mean final difference was 5% (2% to 8%). In the pyeloplasty group mean initial difference in percent function was 16% (range 8% to 30%) and mean final difference was 7% (2% to 16%). With close followup and prompt pyeloplasty renal function improved to greater than pre-deterioration levels in all kidneys.
CONCLUSIONS: These data represent the natural history of severe bilateral newborn hydronephrosis. Renal dilatation and function improve with time in most kidneys. Close followup is required in the first 2 years of life to identify the subgroup (35%) of children with obstruction that requires prompt surgery. Such an approach prevented permanent loss of renal function. Nonoperative management with close followup during the first 2 years appears to be a safe and recommended approach for neonates with primary bilateral ureteropelvic junction type hydronephrosis.