Non-refluxing Primary Megaureter in Children Resolves From Proximal to Distal

Abstract

Objectives: To evaluate a population of children with non-refluxing primary megaureter (NRPM), we investigated spontaneous resolution of ureteral dilation and the pattern (proximal to distal or distal to proximal) in which it occurs.

Methods: From our prospectively collected prenatal hydronephrosis (HN) database (0-24 months, 2008-2017), selecting those with NRPM (n = 92). We excluded patients who underwent surgery (n = 20), children with <6 months follow-up (n = 2) and without a voiding cystourethrogram (VCUG) (n = 4). Images were segregated into 198 ureteric segments (proximal/mid/distal). We defined resolution as Society for Fetal Urology (SFU) (0/1), anteroposterior diameter (APD) <10 mm, and ureteric dilatation <5 mm. Descriptive statistics and Kaplan-Meier curves were created for time-to-resolution analyses.

Results: Of 66 patients and 198 ureteral segments, median age at presentation was 2 months (0-12), 83% were male (33% circumcised). Mean APD at baseline was 11 ± 4 mm, and 79% had (SFU 3/4) HN. Mean dilatation of ureteral segments (mm) at baseline was: 9 ± 2 proximal, 9 ± 2 mid, and 11 ± 3 distal. At a median follow-up time of 26 (7-83) months, dilation of 55 (83%) proximal, 48 (72%) mid, and 22 (33%) distal ureteric segments had resolved. Overall, HN resolution occurred in 76% of patients. Resolution rates were similar for proximal/mid-ureters (83% vs 72%; P = .20); however, they were significantly different from distal segments (83% proximal vs 33% distal; 72% mid vs 33% distal, P <.01).

Conclusion: Our data suggest that spontaneous resolution of NRPM follows a proximal to distal progression. Distal ureteric dilatation takes up to 10 months longer to resolve compared to that of proximal and mid-ureteric segments, as well as that of the renal pelvis.