© 2019 American College of Radiology An acute scrotum is defined as testicular swelling with acute pain and can reflect multiple etiologies including epididymitis or epididymo-orchitis, torsion of the spermatic cord, or torsion of the testicular appendages. Quick and accurate diagnosis of acute scrotum and its etiology with imaging is necessary because a delayed diagnosis of torsion for as little as 6 hours can cause irreparable testicular damage. Ultrasound duplex Doppler of the scrotum is usually appropriate as the initial imaging for the acute onset of scrotal pain without trauma or antecedent mass in an adult or child. 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 include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.