Ultrasound in Early Pregnancy: Viability, Unknown Locations, and Ectopic Pregnancies.

Ultrasound is essential in the evaluation and management of pregnancies of unknown location. Differential diagnoses include early pregnancy loss, pregnancy of unknown location, and ectopic pregnancies. Both transabdominal and transvaginal routes should be available, in addition to physical examination, for complete evaluation. Diagnostic criteria for early pregnancy loss have expanded in recent years to ensure false positive results do not lead to inappropriate evacuation of desired pregnancies.