Introduction: Duplex collecting system is a common congenital urinary system anomaly and is usually asymptomatic. Vascular variations associated with a duplex system are common but haven't been reported as obstructive.
Case report: 14-month-old female had a right sided incomplete ureteral duplication complicated by lower pole hydroureteronephrosis due to distal ureteral obstruction by an aberrant vessel crossing the bifid ureters at ureteric junction of these bifid ureters. Prenatal imaging detected right hydronephrosis. Magnetic resonance suggested a diagnosis of duplicated ureters. At surgery, an aberrant artery compressed the lower moiety ureter at the bifid ureteric junction. The stenotic section was resected and ureter segments were anastomosed. The occluding small artery was not resected to preserve vascularization.
Discussion/conclusion: An anatomical vascular variation can cause proximal ureteral dilatation and segmental hydronephrosis in a bifid system.
Keywords: Duplex collecting system; aberrant vessel; children; hydroureteronephrosis; lower moiety; ureteral obstruction.