Prenatal diagnosis and postnatal outcome of pelvic kidneys.

Objective: To assess the prevalence of pelvic kidneys during prenatal sonographic examinations in the second and third trimesters and to examine postnatal outcome.

Methods: Prenatal sonographic findings and postnatal follow-up data of fetuses with prenatal diagnosis of pelvic kidneys were analyzed. Routine (n = 10 079) and indicated (n = 17 732) second and third trimester scans were performed in 27 811 fetuses. A pelvic kidney was defined as one located within the fetal bony pelvis and in close approximation to the bladder. Postnatal evaluation consisted of renal ultrasound and/or dimercapto-succinic acid scan.

Results: A total of 36 newborns with postnatally confirmed pelvic kidneys were included in this analysis. Median gestational age at diagnosis was 25 weeks; half (18/36) were recognized after 24 weeks. The prevalence of pelvic kidneys in this cohort was 0.14%. Postnatally impaired renal function was present in 33% of the pelvic kidneys of children, but overall renal function remained normal. No serious complications occurred in the 31 fetuses with long-term follow-up, except in 1 case, which required nephrectomy due to multicystic dysplasia of the pelvic kidney.

Conclusion: Pelvic kidneys are common and can be easily detected prenatally. Prognosis is favorable in the vast majority of the cases.