[Outcome of neonates born with unilateral multicystic dysplastic kidneys]

To review our experience of neonates with unilateral multicystic dysplastic kidneys (MCDKs) and to plan how to manage this anomaly.

Forty-eight neonates (30 boys, 18 girls) with unilateral MCDK were referred to our institute between August 1991 and February 1999. Urological evaluation was performed by USG, VCUG and radionuclide study. Follow-up period was 15 month to 106 months (Ave. 54 months).

Forty-five of 48 (93.8%) MCDKs were found prenatally. No surgical procedure was performed in utero. Seven (14.6%) had low grade vesicoureteral reflux (ipsilateral 5, contralateral 2). Dilation of contralateral upper urinaly tract was detected in 16 (33.3%) neonates and diuretic renography revealed 4PUJ obstruction and 2 mid-ureteral stenosis. Although 29 of 48 (60.4%) MCDKs were large, no neonate showed mass effect which caused vomiting or dyspnea. All MCDKs except two, which removed because of ipsilateral ureterocele or ectopic ureter, were followed conservatively. Two boys had nephrectomy when they became 5-year-old on their parent's request. Surgical correction of contralateral urinary tract anomaly, 3 pyeloplasty and 2 end-to-end ureteral anastomosis, was performed. All neonates but one with contralateral hypodysplastic kidney had good renal function. Neither hypertension nor malignant tumor had occurred.

These findings suggest that neonates with unilateral MCDKs can be treated conservatively only if they have no contralateral serious anomaly. Surgical intervention is not necessary for unilateral MCDKs before and after birth but socially and/or economically it depends on patients' request.