The natural history of the multicystic dysplastic kidney – Is limited follow-up warranted?

Abstract Objective Imaging of patients with multicystic dysplastic kidney (MCDK) has increased over the past three decades. This increased use of imaging has provided additional insights into the natural history of MCDK. The present study looked at this data for predictors of involution and associated anomalies. Methods and materials Institutional review board approval was obtained for this retrospective study. The University of Michigan Departments of Urology and Radiology records were searched to identify unilateral MCDK patients during 1980–2012. Available clinical, radiological and surgical records were reviewed, and pertinent data were recorded. The log-rank test and a Cox proportional regression analysis were performed to identify predictors of MCDK involution. Probability of involution over time was assessed using Kaplan–Meier methodology. Results 301 unilateral MCDKs were identified; 195 (64.8%) were detected antenatally. Of the MCDKs found, 136 (45.2%) were in girls; 160 (53.2%) were right-sided. Mean size at baseline was 5.0 ± 0.2 cm (Mean ± SE). Associated abnormalities included: contralateral ureteropelvic junction obstruction ( n = 10; 3.3%); contralateral ureterovesical junction obstruction/primary megaureter ( n = 6; 2.0%); ipsilateral VUR ( n = 21; 7.0%); contralateral VUR ( n = 63; 20.1%); and renal fusion anomaly ( n = 4; 1.3%). The cumulative probability of involution was: 9.8% at one year, 38.5% at five years, and 53.5% at ten years of age. Baseline MCDK size was the only significant predictor of involution at bivariate ( p