Long-term follow-up of neonatally diagnosed primary megaureter: rate and predictors of spontaneous resolution.

Objective: Primary megaureter (PM) represents 6-10% of all antenatal displaced urinary malformations. Spontaneous resolution of PM is a well-known event. This long-term follow-up study evaluated the incidence and rate of resolution of PM. Some predictive factors were revised, based on morphological classification and scintigraphic pattern.

Material and methods: Sixty neonates with PM were followed. The diagnosis was confirmed by ultrasound examination and (99m)Tc-DTPA diuretic renal scan. All the observed patients underwent antibiotic prophylaxis. All conservatively treated children were followed from 6 months to 15 years. Follow-up consisted of monthly urine cultures, renal ultrasound and DTPA diuretic renography. Hydroureteronephrosis was considered to have resolved when a retrovesical cross-sectional diameter of ureter less than 6 mm was found.

Results: In total, 72 PM were identified in this series. At the end of the follow-up period, 38 PM (52.8%) had resolved, in 18 PM (25%) ureteral dilatation persisted and 16 PM (22.2%) required a surgical procedure. The median age at resolution was significantly affected by presenting hydronephrosis grade and cross-sectional diameter at diagnosis, but not by gender. The (99m)Tc-DTPA renogram results showed no functional impairment in resolved and persisting cases, even after long-term observation.

Conclusions: The data show that 22% of neonatal PM require surgical treatment. Poor drainage on (99m)Tc-DTPA scan, grade IV-V hydronephrosis and ureteric diameter more than 15.0 mm were statistically significant and independent predictive factors for surgery. The time to spontaneous resolution in neonatally diagnosed PM may exceed 3.6 years, after which recovery is rare.