Transvaginal sonographic detection of embryonic-fetal abnormalities in early pregnancy

Objective: To estimate the detection rate of abnormalities by transvaginal ultrasound in early pregnancy. Methods: We prospectively analyzed records of 3592 sequential pregnant wome n at 10-16 weeks' (singleton) gestation (mean 13 weeks and 2 days). After e xclusion of 114 women, there were 3478 women in the study. Each woman under went a transvaginal sonographic survey for fetal anomalies as well as biome tric measurements. Fetuses diagnosed with malformations were followed to de livery, and those without underwent transabdominal sonography at 18-24 week s' gestation. Results: The anomaly detection rate by transvaginal ultrasound was 51.6% (3 3 of 64; 95% confidence interval [CI] 38.7, 64.2) in early pregnancy, and t he detection rate by transvaginal ultrasound combined with second-trimester transabdominal ultrasound was 84.4% (54 of 64; 95% CI 73.1, 92.2). Cystic hygroma and fetal hydrops were the anomalies detected most frequently by tr ansvaginal ultrasound. Low detection rates for abnormalities of the face an d of the cardiac, skeletal, and urinary systems were found even when both m ethods were used. Conclusion: Transvaginal sonography appears to be an effective way to ident ify many congenital fetal anomalies in early pregnancy. There is a good pro bability of diagnosing cystic hygroma and fetal hydrops, although other abn ormalities, particularly heart defects, are associated with lower detection rates. (Obstet Gynecol 2000;96:328-32. (C) 2000 by The American College of Obstetricians and Gynecologists).