What every radiologist should know about adnexal torsion.

Adnexal torsion is the fifth most common gynecologic surgical emergency, requiring clinician and radiologist awareness. It involves the rotation of the ovarian tissue on its vascular pedicle leading to stromal edema, hemorrhagic infarction, and necrosis of the adnexal structures with the subsequent sequelae. Expedient diagnosis poses a difficult challenge because the clinical presentation is variable and often misleading. Adnexal torsion can mimic malignancy as it can take a subacute, intermittent, or chronic course, and thereby can be complicated to diagnose. The torsion may occur in the normal ovary but is usually secondary to a preexisting adnexal mass. Early surgery is necessary to avoid irreversible adnexal damage and to preserve ovarian function especially in children and young women. Pelvic ultrasound forms the foundation of diagnostic evaluation due to its ability to directly and rapidly evaluate both ovarian anatomy and perfusion. Moreover, it is a noninvasive and accessible technique. However, the color Doppler appearance of the ovary should not be relied upon to rule out torsion because a torsed ovary or adnexa may still have preserved arterial flow due to the dual blood supply. MR and CT may be used as problem-solving tools needed after the ultrasound examination but should not be the first-line imaging modalities in this setting due to ionizing radiation and potential time delay in diagnosis. The goal of this article is to review the adnexal anatomy, to familiarize radiologists with the main imaging features, and to discuss the main mimickers and the most common pitfalls of adnexal torsion. Main points Adnexal torsion is an uncommon gynecological disorder caused by partial or complete rotation of the ovary and/or the Fallopian tube about the infundibulopelvic ligament. The ovaries receive a dual blood supply from the ovarian artery and uterine artery. The lack of pathognomonic symptoms and specific findings on physical examination makes this entity difficult to diagnose. Since the right adnexa are most commonly involved, symptoms may mimic acute appendicitis. Persistence of adnexal vascularization does not exclude torsion. In the pediatric age group, gray-scale ultrasound is the best modality of choice. Obtaining CT and/or MR images should not delay treatment in order to preserve ovarian viability.