Background: Unilateral renal agenesis is a rare finding. There are no large-scale studies reporting this finding in early pregnancy.
Objectives: To evaluate the incidence of unilateral renal agenesis (URA) and of associated anomalies diagnosed by early prenatal trans-vaginal sonography.
Methods: We performed a retrospective chart review of all 59,382 trans-vaginal scans performed at 14-16 weeks gestation by a single operator at different clinics during the period 1994-2013.
Results: The incidence of URA was 1:1212 (49/59382 cases). Associated anomalies were diagnosed in 22 cases (45%). Renal anomalies were diagnosed in 22.4%. Extra-renal anomalies (with exclusion of a single umbilical artery or nuchal edema as isolated findings) were diagnosed in 24.5%. Ambiguous genitalia were diagnosed in 8.2%.
Conclusions: URA is a rare finding in early trans-vaginal sonography. Associated anomalies are very common and should be sought.