Transvaginal sonographic measurement of fetal kidneys in the first trimester of pregnancy.

Fetal renal size late in the first trimester of pregnancy was evaluated by transvaginal ultrasonography in 50 patients not at risk for congenital kidney disease and whose pregnancies resulted in a normal outcome. Both kidneys were reliably identified in all patients scanned at 12 weeks, 13 weeks, and 14 weeks, menstrual age. Kidney diameter measurements obtained in this study are presented for reference in evaluating patients in late first trimester whose fetuses are at risk for kidney abnormalities.