Multicystic dysplastic kidney: natural history from in utero diagnosis and postnatal followup.

Based on our experience with 13 in utero diagnoses we report the changes that may occur in the ultrasonic appearance of a multicystic dysplastic kidney. Macrocysts appear obvious only in the early third trimester of pregnancy. After reaching a maximum size the cysts start to involute either in utero or after birth, which may lead to a small noncystic mass, the so-called aplastic kidney, or even to complete disappearance of the entire dysplastic kidney. The dysplastic kidney seems vulnerable to anoxia or infection, and necrosis may supervene. The multicystic dysplastic kidney is a progressive and changing disorder. If its radiological appearance is typical management may be conservative with ultrasonic monitoring. Nephrectomy should be done if there is any abnormal clinical or ultrasonic change.