Congenital urinary tract dilation: when is it clinically significant and when should it prompt intervention?

Urinary tract dilation is the most common urinary tract anomaly detected on prenatal ultrasonography. Postnatal follow-up, the necessity of advanced imaging, and indications for surgical intervention remain confusing and subject to ongoing debate.

Our aim is to evaluate the etiology, clinical and radiological characteristics of congenital urinary tract dilation, and assess the timing and outcomes of spontaneous resolution, advanced imaging, surgical interventions, and postoperative follow-up.

This retrospective study evaluated the etiology, clinical and radiological features, and outcomes of congenital urinary tract dilation in children at Adiyaman University Pediatric Nephrology Clinic between November 2021 and 2023. Urinary tract dilation was classified by ultrasonographic anteroposterior (AP) diameter on postnatal urinary system ultrasonography as normal (<10 mm), mild-moderate (10-15 mm), or severe (>15 mm).

Among 341 patients (71.3% male), 36.2% had severe and 63.8% had mild-to-moderate urinary tract dilation. Mean AP diameter was 14.4 ± 7.0 mm. Urinary tract dilation resolved in 96.2% of patients, typically within 3-44 months (mean 11 ± 6.3). Surgery was required in 22.6% of patients, mostly for ureteropelvic junction obstruction and vesicoureteral reflux, and was significantly more common in severe cases (56.1% vs. 3.7%, p < 0.001). Severe urinary tract dilation was significantly associated with family history of congenital anomalies of the kidney and urinary tract, history of urinary tract infection (UTI), reduced kidney function, and abnormal dimercaptosuccinic acid renal scintigraphy findings (p < 0.001). ROC analysis demonstrated high predictive performance (area under the receiver operating characteristic curve (AUC) = 0.936, 95% confidence interval: 0.908-0.963; p < 0.001). An AP diameter cutoff value of 17 mm predicted surgical intervention, with 88.3% sensitivity and 84.1% specificity.

An AP diameter ≥17 mm, decreased differential kidney function, UTI history, and family history of congenital anomalies of the kidney and urinary tract are strong indicators for surgical intervention.