History: Child with multiple urinary tract infections.
This is a case of vesicoureteral reflux with a completely duplicated right collecting system. Vesicoureteral reflux is graded as follows:
1. Grade 1 – reflux into a normal caliber ureter only
2. Grade 2 – reflux into the ureter, renal pelvis, and calyces with out dilatation
3. Grade 3 – mild dilatation of the ureter and minimal blunting of the calyces
4. Grade 4 – moderate dilatation of the ureter and blunting of the calyceal fornices
5. Grade 5 – gross dilatation of the ureter, pelvis and calyces, ureteral tortuosity, loss of papillary impressions
Revisiting the image above in our case I would call this grade 3 vesicoureteral reflux on the left, grade 4 vesicoureteral reflux on the right lower pole moiety, and grade 5 vesicoureteral reflux of the right upper pole moiety.
Duplication of the collecting system is exactly what it sounds like, a kidney which is separated into two separate moieties being drained by two separate renal pelvises and ureters. There are many variations of duplicated collecting systems broken into broad categories of partial and complete. Classically (which means that it doesn’t always happen this way) the ureter draining the upper pole moiety inserts ectopically medially and inferiorly to the lower pole moiety ureter which has an anatomically normal insertion. The upper pole ureter will typically have a ureterocele at the bladder, which is prolapse of the ureter into the bladder lumen. This causes obstruction of the upper pole moiety and reflux of the lower pole moiety. This is referred to as the Weigert-Meyer rule. In the case above, this rule is not followed. The upper pole ureter on the right is not obstructed because contrast is refluxing into it. When it is obstructed it typically causes the lower pole moiety to be compressed inferiorly and leads to a “drooping lilly” sign on VCUGs.
Bilateral duplication can be seen in 10-20% of cases.