Role of computed tomography in imaging of endometriosis

Endometriosis is a chronic systemic disease characterized by the presence of endometrium-like glands and/or stroma outside the uterus, usually with an associated inflammatory process. It affects around 5-10% of women worldwide, with chronic pelvic pain and infertility being the predominant symptoms. Although suspected clinically, transvaginal ultrasound (TVUS) and magnetic resonance imaging (MRI) are the primary imaging tools for diagnosing pelvic endometriosis, as well as helping in pre-surgical mapping. Computed tomography (CT) is not the preferred imaging modality for detection or depiction of disease extent. However, CT of the abdomen and pelvis is often performed as the initial imaging test in women presenting with acute or non-specific abdominal/ pelvic pain. CT features of endometriosis can vary depending on the organ affected, and the correct diagnosis is often not suspected due to its nonspecific CT appearance and overlap with other pathologies. Ovarian endometriomas (OMAs), the most recognized phenotype of endometriosis, may appear as hyperdense adnexal masses either in the expected location of the ovaries or positioned posterior to the uterus. Endometriomas may rupture, presenting with hemoperitoneum. The uterus may be distorted and acutely retroflexed from deep endometriosis along the posterior uterine surface. The bowel can be affected by endometriosis, especially the rectosigmoid colon, presenting as enhancing soft tissue bridging from the posterior uterine surface to the anterior rectal wall. Small bowel involvement may present with recurrent small bowel obstructions. Involvement of the urinary system may present with ureteral obstruction or a bladder wall mass. Given such varied appearances, a high degree of clinical suspicion and knowledge of CT features suggestive of endometriosis is required to facilitate an early diagnosis. This review paper therefore describes the imaging findings of endometriosis that can be recognized on an abdominopelvic CT, with the goal of decreasing the existing delay to accurate diagnosis and improving long term patient outcomes.