The fate of prenatally diagnosed primary nonrefluxing megaureter: do we have reliable predictors for spontaneous resolution?

Objectives: To compare predictive values of current morphologic parameters with congenital renal damage associated with severe megaureter.

Methods: A retrospective analysis was performed using records of 37 patients (50 megaureters) referred before birth for a primary megaureter. Mean follow-up was 26 months (range, 1 to 8 years).

Results: Dilatation resolved spontaneously in 46 of 50 ureters. Only 4 of 37 patients required surgery (10.8%) after a mean follow-up of 58 months (range, 32 to 80 months). Average time to resolution was 24 months (range, 1 to 82 months) and was independent from sex, side, and bilaterality. A weak correlation was found with initial anteroposterior pelvic diameter, ureteral diameter, and separate function at renogram. A significant correlation (P <0.02) was found between megaureter type and time elapsed to spontaneous resolution. As far as differential function was concerned, mean values were significantly lower among type III megaureters, which had the lowest rate of resolution.

Conclusions: The fate of severe megaureter seems strongly influenced by congenital renal damage secondary to a developmental abnormality of the ureteric bud. A poor resolution rate has to be expected in these cases; surgery must be reserved for symptomatic cases but has no influence on pre-existing renal damage.