US findings of adnexal torsion in children and adolescents: size really does matter

Background Adnexal torsion is rare, and symptoms are nonspecific. Clinicians often rely on US examinations to evaluate girls with abdominal or pelvic pain. Objective To determine which sonographic findings can predict adnexal torsion by comparing pediatric and adolescent patients with surgically confirmed torsion (cases) to those without torsion (controls). Materials and methods Cases and controls were identified retrospectively by searching 7 years of medical record and radiology databases. An adnexal ratio was calculated as the volume of the affected adnexa divided by the volume of the unaffected adnexa. Results We identified 61 menarchal subjects: 33 cases and 28 controls. Adnexal volume was larger in cases than in controls (185 vs. 37.8 ml, P < 0.001). A volume of >75 ml was more common in cases than in controls (64 vs. 15%, P < 0.001). No cases had an adnexal volume of <20 ml ( P < 0.001). The adnexal ratio was larger in cases than in controls (16.1 vs. 6.7, P < 0.001). An adnexal ratio of >15 was seen in 40% of cases and in no controls ( P = 0.08). Doppler US results were not predictive of torsion. Conclusion An adnexal volume of <20 ml is strong evidence against adnexal torsion in menarchal females. In this age group, the diagnosis of torsion cannot be established by US examination alone.