The natural course in children with unilateral multicystic dysplastic kidney

Purpose: Advances in modern ultrasonography combined with a dimer-captosuccinic acid (DMSA) renal scan have permitted the diagnosis of a multicystic dysplastic kidney (MCDK) with a high degree of certainty. Most multicystic dysplastic kidneys undergo spontaneous involution during follow-up, as demonstrated by serial ultrasonography. The purpose of this study was to contribute to a better understanding of the natural history of a MCDK, and suggest guidelines for follow-up of a MCDK. Materials and methods: Between November 1988 and May 2004, 142 children with a MCDK were diagnosed at our institute. A retrospective data analysis was carried out on 38 patients who were conservatively managed and followed for more than 6 months. Follow up ultrasonography examinations were performed every 6 months until patients were 5 years old, and annually thereafter. Patients were divided into simple and complex MCDK based on postnatal physical examination and renal ultrasonography. A simple MCDK was defined as unilateral renal dysplasia without genitourinary abnormalities. Complex MCDK included patients with unilateral renal dysplasia, but with other genitourinary abnormalities. Results: The follow-up periods ranged from 6 to 76 months, with a median of 21.5 months. Partial and complete involution of the affected kidney was observed in 6 (15.8%) and 8 (21.1%) patients, respectively. There was no significant difference in the median involution time between the groups. The median time to involution in all patients was 36 months. Conclusions: Conservative management for a MCDK appears to be a safe option. Because of a complex MCDK has a high incidence of UTI, prophylactic antibiotics may be required. We recommend the long-term follow-up of a MCDK using ultrasonography monitoring.