RESUMEN
Adnexal torsion in the third trimester is very rare. Because of changes in uterine size and anatomical position of abdominal organs, the diagnosis of adnexal torsion during pregnancy is difficult to establish on the basis of symptoms, physical findings, or radiologic technique. Delayed diagnosis and management can lead to serious complications, so a rapid, reliable, and accurate imaging is needed to evaluate pregnant women with acute abdomen. Ultrasonography has been the initial imaging modality of choice in evaluation of obstetric patient, but it is technically difficult in the third trimester. MR imaging can provide a broad evaluation of the pelvic organs and enables diagnosis of many causes of acute abdomen, especially in the third trimester. We have experienced a case of Parovarian cyst torsion at pregnancy 29+4 wks and reviewed it briefly.