First-Trimester Ultrasound

Since the 1980s, development of high-resolution transvaginal ultrasound transducers has significantly improved ultrasound evaluation at earlier gestational ages. Although many indications exist for first-trimester ultrasound in pregnancy, more emphasis has been placed on assessment of fetal anatomy recently. In turn, congenital diagnoses can also be made earlier in pregnancy, raising the question of whether anatomic assessment in the first trimester is one of choice or obligation. Combining transvaginal and transabdominal approach yields the highest detection rate overall. Some studies have shown that more than half of all anomalies and almost all severe anomalies can be detected on early scans.