Duplex Collecting System

A 2 year old girl had a urinary tract infection. A micturating cystourethrogram was performed. There is bilateral vesicoureteric reflux into dilated collecting systems. On the left there is a duplex collecting system.
The ureter draining the lower moeity typically has a normal insertion site at the trigone. The ureter draining the upper moeity typically has an ectopic insertion distal to the VUJ (bladder, urethra, or genital tract).
The ectopic ureter is prone to obstruction and the orthotopic ureter to vesicoureteric reflux (although clearly both have refluxed here). There may be a ureterocoele associated with the ectopic ureter.
Reference: Radiology Review Manual 3rd ed. W Dahnert 1996
Credit: Dr Laughlin Dawes
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