Pilot screening for fetal malformations: possibilities and limits of transvaginal sonography.

Two thousand and ninety-seven unselected pregnant women bearing 2114 fetuses were examined by transvaginal sonography at 14 weeks of gestational age and rescreened via transabdominal sonography at 21 weeks (excluding those who chose termination of pregnancy). Twenty-five of 47 anomalies were correctly identified at the first scan, 15 malformations were missed and detected only during the scan, two were identified later in pregnancy, and five were identified after birth. Ten of 12 abnormalities were detected correctly on the basis of ultrasonographic findings. Transvaginal sonographic screening for fetal malformation, in our experience, permits the detection of more than 50% of all fetal structural defects and 75% of all aneuploidies early in pregnancy.