Fetal pelvic kidney: a challenge in prenatal diagnosis?

The objective of this study was to establish ultrasonographic guidelines for the prenatal diagnosis of fetal pelvic kidneys and assess the relationship to clinical outcome. The records of all ultrasonographic diagnoses of a fetal pelvic kidney between 1 January 1991 and 31 December 1993 were reviewed. After review of the sonographic evaluation, the prenatal records were obtained, to assess demographic data as well as the obstetric course and neonatal outcome. If a fetal pelvic kidney was suspected on prenatal ultrasound examination, its precise location and size were recorded and compared with neonatal sonograms. Twenty-six cases of fetal ectopic kidney were diagnosed of which 13 were on the right side and 13 on the left (24/26 cases were diagnosed in the late second trimester). The size of the ectopic kidney did not differ from that of the normal kidney. Except for one case of hydronephrosis, there were no associated structural anomalies. All prenatal diagnoses were confirmed by postnatal sonograms and all neonates had normal renal function. Our conclusions are that prenatal sonographic detection of fetal pelvic kidney is feasible, although in most cases the diagnosis is made beyond 24 weeks' gestation. The importance of prenatal diagnosis is that the parents can be reassured that normal renal function is highly probable and that early neonatal intervention is usually unnecessary.