BACKGROUND: Most patients with primary obstructive megaureter (POM) will improve without surgical intervention. For this reason, establishing early predictors for spontaneous resolution of POM remains a topic of significant interest and could prevent unnecessary surgery in this population. Previous studies have shown variable predictive ability from early ultrasound features. Here, we aimed to describe and develop predictors for spontaneous resolution of POM from early ultrasound measures.
METHODS: Children referred to our institution between 2007 and 2023 for POM were reviewed. PNM was defined as hydroureteronephrosis with ureteral dilatation >7mm. We excluded patients with other etiologies for upper tract dilatation. Resolution was defined as decrease in hydronephrosis to <10 mm anteroposterior diameter (APD) or SFU grade ≤ 2, or ≤7 mm in hydroureter. Patients were censored if they underwent surgical intervention or were lost-to-follow-up before documenting resolution. Kaplan-Meier curves were drawn to illustrate the cumulative resolution rate and determine univariate associations. Cox proportional hazards regression was performed to identify significant predictors for early resolution, binary area-under the receiver-operator characteristic (AUROC) and concordance index (c-index) was calculated. RESULTS:A total of 195 patients were included, with a median index age of 2 months and a median follow-up of 29 months; of these and 118 patients (60%) reached spontaneous resolution during monitoring. APD >15 mm (OR 0.28, 95%CI 0.16, 0.50), high-grade hydronephrosis (OR 0.42, 95%CI 0.29, 0.61), ureteral dilation > 10 mm (OR 0.45, 95%CI 0.31, 0.66), and ureter tortuosity (OR 0.48, 95%CI 0.31, 0.74) at presentation were independently associated with a lower likelihood of resolution.A Cox regression model trained on these predictors achieved a c-index of 0.76 and allowed development of a simplified POM resolution scoring index to discriminate between low- and high-risk patients with an AUROC of 0.77 for spontaneous resolution. As shown in Figure, patients with a score < 2 have an increased likelihood of spontaneous resolution (HR 2.77, 95%CI 1.92, 4.00). CONCLUSIONS:
Our study contributes to understanding POM by highlighting the independent predictive value of early sonographic features, including ureteral diameter >10 mm and anterior-posterior diameter > 15mm are predictive for delayed resolution. This provides a basis for the scoring index described in this work, with a higher index score being associated with non-resolution. Future research should extend these findings through prospective, long-term studies that consider a more comprehensive array of clinical outcomes with multi-institutional validation.
