Imaging of Acute Pelvic Pain

Pearls and Pitfalls in Imaging of Pelvic Adnexal Torsion: Seven Tips to Tell It's Twisted

Pelvic adnexal torsion is a collective term referring to twisting of an ovary, fallopian tube, or paraovarian cyst on its axis with varying degrees of vascular compromise. Although it is the fifth most common gynecologic emergency, the diagnosis is challenging and often missed due to symptoms, physical examination findings, and imaging features that are nonspecific. Delay in salvage surgery may lead to ovarian or tubal loss, dysfunction, and infertility. The tips shared herein are based on the authors' observations of key clinical and imaging features of torsion, with the intent of heightening radiologists' index of suspicion and diagnostic accuracy in a clear and memorable fashion. Clinically, severe acute pain with a known adnexal mass or of severity to elicit nausea or vomiting should raise concern. At imaging, features of ovarian edema are key to the diagnosis, including asymmetric ovarian enlargement, peripheralized follicles, adjacent free fluid, and foci of stromal hemorrhage. The converse finding of symmetric nonenlarged ovaries in a normal location with any imaging modality has a high negative predictive value for torsion, obviating the need for additional imaging. The whirlpool sign (twisted vascular pedicle), abnormal ovarian location, and uterine tilting are additional key imaging manifestations. The presence of color Doppler flow or contrast enhancement only suggests that an ovary is still viable and should not be used to exclude the diagnosis of torsion. In cases of isolated tubal or paraovarian cyst torsion, the ovaries may appear normal; therefore, recognition of this entity along with appreciation of several key imaging findings may assist with this difficult diagnosis. An invited commentary by Dighe is available online. Online supplemental material is available for this article. ^©RSNA, 2021.