Abstract
Vaginal bleeding is a relatively common occurrence in the first trimester of pregnancy, but can be distressing for both patients and clinicians. Differential considerations include normal intrauterine pregnancy (IUP), a nonviable IUP, an ectopic pregnancy (EP), or much less commonly gestational trophoblastic disease (GTD). Although the diagnosis of EP, nonviable IUP, and GTD is important, it is also crucial to avoid harming potentially normal pregnancies through early medical or surgical treatment. Fortunately, most diagnoses can be made using a combination of ultrasound (US), serum human chorionic gonadotropin levels, and physical examination. When a diagnosis is in question, serial examinations and close clinical evaluation is paramount. Occasionally, MRI of the pelvis without contrast may be helpful in problem-solving for challenging cases, where grayscale US is limited or when there is high concern for nontubal EP. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.