Structural genitourinary defects detected in utero.

Fetal genitourinary anomalies are detected with increasing frequency due to the large numbers of fetuses that undergo screening ultrasonography (US) for nonspecific indications. One hundred seventy-seven patients were evaluated for fetal urinary abnormalities over a 2-year period. Fetal hydronephrosis accounted for 154 (87%) of the cases, with the remaining diagnoses including multicystic dysplastic kidney, autosomal recessive polycystic kidney disease, and renal agenesis or hypodysplasia. Ureteropelvic junction obstruction was the most common postnatal anatomic abnormality (29%), with a large number of cases of prenatally diagnosed hydronephrosis resolving either prenatally (33%) or postnatally (24%). Prenatal US findings were retrospectively analyzed with regard to the degree of hydronephrosis at different stages of gestation. Data showed that there is a gradual rise in anteroposterior renal pelvic diameter during gestation and that there is a correlation between this diameter and the ultimate renal outcome in regard to surgical repair. This information can provide guidance in making recommendations to parents and physicians.