Unilateral Fetal Renal Abnormalities: Are They Really Isolated?

Our objective was to describe the association between unilateral fetal renal abnormalities and other major anomalies that were not apparent in the second trimester.

A review of the ultrasound database identified fetuses with suspected unilateral renal agenesis, unilateral multicystic dysplastic kidney, and renal ectopia from 2005 to 2014. Neonatal records were reviewed to identify anomalies not suspected in the second trimester, and postnatal imaging studies were reviewed. Categorical data were compared by &x003C7;(2) analysis and the Fisher exact test.

We identified 102 cases, including 36 with suspected renal agenesis, 28 with suspected multicystic dysplastic kidney, and 38 with suspected renal ectopia. There were 8 cases (7.8%) with major anomalies not suspected in the second trimester. In 5 cases (4.9%), there were no associated findings in the second trimester. There were no significant differences in the rates of unsuspected abnormalities between the 3 groups. There was a trend toward a higher rate of unsuspected anomalies in the cases with a single umbilical artery compared to those with a 3-vessel cord (28.6% vs 6.3%; P= .09).

In fetuses with unilateral renal abnormalities, major anomalies that were not suspected in the second trimester were uncommon. However, patients should be aware of the possibility that other major anomalies could subsequently be identified, and the outcome may depend on more than postnatal renal function.