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Background
Multicystic dysplastic kidney (MCDK) is associated with a number of other genitourinary anomalies, the most common being vesicoureteral reflux (VUR). Historically, a voiding cystourethrogram (VCUG) was recommended in all infants with MCDK to allow for identification of significant contralateral genitourinary abnormalities and the prevention of reflux nephropathy. Recent studies have questioned the necessity of VCUG in all MCDK patients given the high rate of spontaneous VUR resolution as well as a predominantly low grade of VUR at diagnosis.
The objective of our study was to determine the clinical significance of contralateral VUR in children with MCDK, thereby assessing the need for routine VCUG.
Methods
A retrospective chart review was conducted, identifying all infants diagnosed with MCDK between January 2000 and December of 2011. VUR was determined by VCUG and graded according to the international system of radiographic grading.
Results
A total of 183 patients were diagnosed with MCDK during the study time frame.
One hundred and forty five patients underwent VCUG testing, with 24 (16.6%) diagnosed with VUR into the contralateral kidney. Low grade (I and II) reflux was diagnosed in 66.7% (15/24) of patients, with moderate-to-high grade reflux diagnosed in the remaining 33.3% (8/24). Of the 8 patients with VUR of grade III or higher, 6 (75.0%) had spontaneous resolution, 1 (12.5%) was lost to follow-up, and 1 (12.5%) required surgical invention for VUR, secondary to break-through urinary tract infections while on antibiotic prophylaxis. Of note, this patient was also found to have a partially duplicated collecting system. To investigate whether renal abnormalities could predict the presence of VUR in the contralateral kidney, we used a mixed design ANCOVA to examine renal growth at three time points as measured by ultrasound, between age and sex-matched groups of patients with MCDK +/- VUR. No significant differences emerged between the groups, although the study was underpowered (power = .38) due to small sample size.
Conclusions
VCUG is unnecessary in children with MCDK, as rate of spontaneous resolution was high in patients with moderate-to-high grade reflux. Our large series identified only one patient requiring surgical intervention for VUR, which could have been identified solely by recurrent urinary tract infections, and an abnormal renal ultrasound.