Abstract Purpose To investigate the accuracy of ultrasound in the diagnosis of adnexal torsion. Materials and Methods Retrospective cohort analysis of 322 women, presenting to a tertiary medical center with acute abdominal pain, who underwent gynecological examination, sonographic evaluation and laparoscopic surgery, between 2010 and 2016. Findings for adnexal torsion were compared among three groups: positive sonographic findings consistent with surgically confirmed adnexal torsion (true positive, n = 228); negative sonographic findings inconsistent with surgically confirmed adnexal torsion (false negative, n = 42); and positive sonographic findings inconsistent with a surgical diagnosis other than adnexal torsion (false positive, n = 52). Outcome measures were sensitivity and positive predictive value of ultrasound, and its specific features, for the diagnosis of adnexal torsion. Results The sensitivity of ultrasound for adnexal torsion diagnosis was 84.4 %, and the positive predictive value was 81.4 %. Edematous ovary and/or tube, as well as positive whirlpool sign had the highest sensitivity and positive predictive value. The false-negative group had the highest frequency of ovarian cysts (p = 0.0086) and the lowest frequency of ovarian edema (p < 0.0001). The false-positive group had the lowest proportion of pregnant women (p = 0.0022). Significantly more women in the true-positive group had a prior event of adnexal torsion (p = 0.026). Conclusion Ultrasound examination is highly accurate in the diagnosis of adnexal torsion. Clinicians should be aware of the presence of demographic and clinical characteristics that may positively or negatively affect sonographic diagnostic accuracy.