For at least 20 years, many researchers have advocated the use of ultrasound in general and transvaginal ultrasound in particular to identify anomalies in the first and early second trimester. Over that period, advances in transducer technology, faster computers, and deepening understanding of developmental anatomy have facilitated such use. Increasing reliance on first-trimester screening brings more and more women with gestations from 11 to 14 weeks to the obstetrician's office, providing an opportunity to expand the narrow viewing angle of the ultrasound probe from the nuchal area to the entire fetus. As time goes on, we may discover additional compelling reasons to shift the first fetal evaluation from the second-trimester to the first-trimester. In the meantime, we find no reason not to widen the viewing angle of transducer probes to assess fetal anatomy at the first-trimester scan. This document discusses evolving applications of first-trimester ultrasound. Scanning can be performed transvaginally or transabdominally, although the transvaginal route is preferred during the first-trimester, because of high-resolution images it yields. Clear images improve reliability and accuracy. However, at times, a combination of transvaginal and transabdominal scanning may be preferred. Both basic and advanced first-trimester ultrasound applications are discussed in this review.Read More