A Case–Control Study of Sonographic Maximum Ovarian Diameter as a Predictor of Ovarian Torsion in Emergency Department Females With Pelvic Pain

Abstract

Background: Color and power Doppler ultrasound are commonly used in the evaluation of ovarian torsion but are unreliable. Because normal-sized ovaries are unlikely to cause torsion, maximum ovarian diameter (MOD) could theoretically be used as a screening test in the ED. Identification of MOD values below which torsion is unlikely would be of benefit to providers interpreting radiology department or point-of-care pelvic ultrasound. Objectives: The objective was to determine if sonographic MOD can be used as a screening tool to rule out torsion in selected patients. Methods: Via a retrospective case–control study spanning a 14-year period, we examined the ultrasound characteristics of patients with torsion and age-matched controls, all presenting to the emergency department with lower abdominal pain and receiving a radiology department pelvic ultrasound for “rule-out torsion.” Standardized data collection forms were utilized. Distributions of MOD were compared and sensitivity, specificity, and likelihood ratios were calculated for multiple cutoffs. Results: We identified 92 cases of surgically confirmed ovarian torsion and selected 92 age-matched controls. In postmenarchal patients the sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of 3- and 5-cm MODs were 100% (96%–100%), 30% (20%–41%), 1.4 (1.3–1.7), and 0 and 91% (83%–97%), 92% (83%–97%), 11.2 (5.5–22.9), and 0.09 (0.04–0.19), respectively. The 5-cm MOD, however, excluded an additional 52 of 84 (62%) postmenarchal patients. Conclusions: A threshold MOD of 5 cm on pelvic ultrasound may be useful to rule out ovarian torsion in postmenarchal females presenting with lower abdominal and pelvic pain.