Imaging description

A three-year-old boy presented with recurrent urinary tract infection. An ultrasound of the urinary bladder and kidneys demonstrated a left-sided ureterocele, hydroureter, and upper pole hydronephrosis (Fig. 61.1a–d). The left kidney demonstrated evidence of a duplicated collecting system with a dilated, obstructed upper pole collecting system and a non-dilated lower pole collecting system (not shown). Echogenic debris in the dilated left upper pole collecting system and ureter suggested the possibility of superimposed pyohydronephrosis. A subsequent voiding cystourethrogram (VCUG) confirmed the ureterocele and showed grade 2 reflux into a non-dilated left lower pole ureter and renal collecting system (Fig. 61.1e, f). The findings are consistent with a duplicated collecting system with a dilated, obstructed upper pole moiety, which ends in an ectopic ureterocele and a non-dilated lower pole moiety, which shows vesicoureteral reflux.

Imaging findings of a duplicated kidney with duplicated ureters comprise the following:

1. Duplicated collecting systems and parenchymal bridge identified on ultrasound. Both upper and lower poles may be normal if there is a partial duplication (bifid pelvis or ureters join) or the two ureters both terminate at or close to the normal orifice.

2. Hydronephrosis on ultrasound, often much more prominent in the upper pole collecting system than the lower pole collecting system.

3. Upper pole moiety: hydronephrosis, tortuous hydroureter, ectopic ureterocele.

4. Lower pole moiety: orthotopic ureter; may show reflux.

5. Drooping lily sign on a VCUG: downward displacement of lower pole calices by a hydronephrotic upper pole moiety.

6. Nubbin sign: scarring, atrophy, and decreased function of the lower pole moiety may simulate a renal mass.

7. Ureterocele disproportion sign: very subtle dysplastic upper pole with a mildly dilated ectopic ureter and ureterocele.