Lessons Learned in Emergency Pelvic and First-Trimester US: Focus on Cognitive Biases.

Nonpregnant and pregnant women who present with acute pelvic pain can pose a diagnostic challenge in the emergency setting. The clinical presentation is often nonspecific, and the differential diagnosis may be very broad. These symptoms are often indications for pelvic US, which is the primary imaging modality when an obstetric or gynecologic cause is suspected. Interpretation of pelvic US may be challenging and a source of confusion and misinterpretation for radiologists. Additionally, cognitive biases in imaging interpretation can contribute to diagnostic errors. Cognitive biases represent systematic errors due to failure of the mental shortcuts that the brain subconsciously uses to produce quicker judgments. There are multiple different types of cognitive biases, all of which may lead to perceptual and interpretive errors. Familiarity with common and uncommon pelvic US findings in the setting of pelvic pain is imperative to assist with prompt and accurate diagnosis. Awareness of potential biases when interpreting pelvic US findings further helps hone the interpretation. The authors illustrate the imaging findings in several peer learning cases of nonpregnant and first-trimester pregnant patients who presented with acute pelvic pain in the emergency setting. Several nonobstetric and nongynecologic causes of acute pelvic pain are included for which pelvic US was the first imaging modality used in diagnosis. Diagnostic errors and cognitive biases in interpretation related to these cases are highlighted. The radiologist's awareness of potential cognitive biases in image interpretation may help to refine the differential diagnosis and mitigate errors. RSNA, 2025 Supplemental material is available for this article.