This article reviews the use of ultrasound in pregnancy pertinent to the emergency physician. The techniques for transabdominal and transvaginal studies are detailed including approaches to gestational dating. Diagnosis of ectopic pregnancy is reviewed focusing on the potential pitfalls: reliance on beta-human chorionic gonadotropin, pseudogestational sac, interstitial pregnancy, and heterotopic pregnancy. Techniques for the identification of placental issues and presenting parts during the second and third trimesters are reviewed. Ultrasound is a safe and effective tool for the experienced emergency physician and is integral to providing high-quality care to pregnant women.