Ovarian torsion is twisting of the ovary which cuts off the blood and lymphatic supply to the ovary. This is often accompanied by severe pain, nausea, vomiting, and possible infection. This occurs most commonly in reproductive age women but can occur at any age. The concern is that ovary will infarct and the tissue will die. This puts the women at risk of infection and abscess.
Pelvic pain is most commonly imaged with ultrasound. Ovarian torsion will often be suspected on ultrasound. Ultrasound allows a full evaluation of the ovaries and uterus. One can also look at how the blood supply is to the tissues. Ultrasound also allows a look at the structures adjacent to the ovaries and whether there is fluid.
Ovarian torsion is difficult to diagnose with imaging. Most commonly, the ovary will be swollen and enlarged. The blood supply will be reduced or abnormal. Most commonly we see reduced or absent venous flow to the ovary. The normal follicles in the ovary will be displaced to the periphery. An underlying cyst or mass may be present. There will often be free fluid in the pelvis.
Normal blood flow to the ovary does not exclude torsion as there is dual blood supply from the ovarian and uterine arteries. It is commonly diagnosed surgically for these reasons. The pre operative diagnosis is difficult. Timely diagnosis is important as the ovary may infarct and not be salvageable. Risk of an infarcted ovary is infection and spread to the blood.
Prompt diagnosis is important. Surgery involves untwisting the ovary. Cases in which the ovary is infarcted involve removing the ovary and tube. Other possibilities for this imaging appearance involve pelvic inflammatory disease. This has a different clinical presentation and distinction should be easy on clinical grounds. Ovarian tumors can also have an enlarged ovary with abnormal flow, however, the presentation will be more chronic.