The application of high-frequency transvaginal sonography offers new opportunities in scanning for malformations during the first trimester of pregnancy. Scanning of the anterior abdominal wall and the umbilical cord insertion at this gestational age is feasible. A cross-sectional study of 61 embryos-fetuses from 7 to 12 weeks of gestation was performed to observe the physiologic midgut hernia. This herniation was detected in 64% of the cases at 8 weeks, in 100% during weeks 9 and 10, and in 25% at 11 weeks' gestation. None of the fetuses studied at 12 weeks had a midgut herniation. Vaginal sonography of the well-dated fetus at 12 weeks can confirm the final development of the anterior abdominal wall.