Prenatally detected primary megaureter: a role for extended followup.

PURPOSE: A high rate of spontaneous resolution of or decrease in urinary tract dilatation is expected for most cases of primary megaureter (PM). We analyzed our results with extended long-term nonsurgical treatment in a group of children diagnosed with prenatally detected PM. We also sought to determine the long-term safety of this approach and the clinical significance of residual hydroureteronephrosis (HUN) when complete resolution does not occur.

MATERIALS AND METHODS: We reviewed our experience with 40 infants with prenatally detected hydronephrosis diagnosed as PM who were initially treated nonoperatively between 1986 and 1999. Patients were followed with ultrasonography, nuclear renography and, in some instances, excretory urogram until stable improvement or complete resolution of HUN was noted. Records for patients who specifically returned for long-term followup history and radiological imaging were also reviewed.

RESULTS: Of 40 patients with 57 megaureters (17 with bilateral PMs) who were followed 4 infants (10%) with severe HUN were diagnosed with diminished renal function by nuclear renography and underwent surgical repair. A total of 27 infants (67.5%, 40 megaureters) with PM who were followed without surgical intervention returned for followup examination and imaging for a minimum of 24 months after initial diagnosis, for a mean of 6.8 years (range 24 to 210 months). Ultrasonography in these patients revealed complete resolution (Society for Fetal Urology grade 1 or less hydronephrosis) in 21 megaureters (52.5%) at a mean of 2.9 years and improved or stable HUN in 19 megaureters (47.5%). Antibiotic prophylaxis was administered to 12 patients beyond the first month of life and discontinued at a mean age of 19.9 months. A subgroup of 10 patients (16 megaureters) from this cohort returned for extended followup imaging at a mean of 13.4 years (range 84 to 210 months) following initial diagnosis. Four patients with documented resolution of HUN had no recurrence during long-term followup. One male with bilateral PMs diagnosed at birth that had been stable but were not resolved at 8-year followup suffered significant worsening in the degree of HUN, diminished renal function on 1 side and a renal stone on the contralateral renal unit at 14-year followup, despite remaining asymptomatic.

CONCLUSIONS: Long-term followup of children with prenatally diagnosed PM with mild to moderate hydronephrosis confirms a high incidence of resolution and improvement. As we have documented 1 case of worsening HUN at 14-year followup, we believe that ultrasonography should be periodically continued until the child reaches adulthood, at least in instances where complete resolution of HUN is not documented.