Imaging of Acute Obstetric Disorders

The aims of a first-trimester ultrasound study include localization of the gestational sac, detection of embryonic demise, detection of multiple pregnancies, and confirmation of gestational age. The American College of Obstetrics and Gynecology and the American College of Radiology do not recommend routine ultrasound screening in the first trimester of pregnancy. Typically, the endovaginal probes used for the assessment of first trimester of pregnancy give more information than transabdominal probes and are typically 5–7.5 MHz. Transabdominal probes used in first trimester are often 3.5–5 MHz. Some of the high-yield topics that are discussed in this chapter include anembryonic gestation, pregnancy termination failure, subchorionic hemorrhage, interstitial, heterotopic, and molar and ectopic pregnancy.