Natural history of patients with multicystic dysplastic kidney - what followup is needed?

Purpose: Most clinicians recommend followup with annual ultrasound for patients with multicystic dysplastic kidney. The aim of this study was to determine whether followup ultrasound provides any clinical benefit. Materials and Methods: We retrospectively reviewed the charts of 73 patients who were diagnosed with multicystic dysplastic kidney between October 1991 and August 2005. Data were analyzed with respect to patient characteristics and followup information. Results: We identified 61 patients (43 boys and 18 girls) with adequate followup. A total of 49 patients (80%) were diagnosed prenatally and 12 (20%) postnatally. Associated urological anomalies were noted in 16 patients (26%). Median followup was 2.6 years (range 6 months to 37.5 years). Ultrasound examinations showed complete involution in 25 patients (41%) and partial regression in 18 (30%). The size of the multicystic dysplastic kidney increased in 1 patient (1.6%) and was unchanged in 17 (28%) without any pathological manifestations. Median age at complete involution was 2.1 years (range 36 days to 13.7 years). Patients with contralateral compensatory hypertrophy had more rapid complete involution. Urinary tract infection developed in 6 patients, of whom 1 was ultimately found to have reflux and 1 had ureteropelvic junction obstruction. Conclusions: In our patients with unilateral multicystic dysplastic kidney ultrasound provided little clinically important information. Our data and a review of the literature suggest that once the diagnosis is made, no urological followup is needed. The primary care provider should monitor patients with multicystic dysplastic kidney for hypertension, abdominal mass and urinary tract infection.