The natural history of the multicystic dysplastic kidney in children.

The objective of this study was to examine the natural history of the multicystic dysplastic kidney and the use of sonography for follow-up studies. A retrospective study was performed on 66 children with a radiological diagnosis of multicystic kidney. The change in size demonstrated on sonograms was examined. Adequate follow-up was available on 55 children over a period of 32 months (range 2-69 months). 40/55 of the kidneys underwent a reduction in size, including 22 which were no longer detectable by ultrasound. 10/55 kidneys showed an increase in size and 5/55 showed no change. Reduction in size occurred at a mean age of 84 weeks (range 20-120 weeks). In conclusion, most multicystic kidneys undergo partial or complete involution over the first 2 years of life. The mean size of the multicystic kidney at diagnosis is a poor predictor of eventual outcome.