Though cystic disease is common in the female pelvis and, in most cases, the ovaries are involved, nonovarian cystic pelvic masses are also found and occur in a number of shapes, sizes, and locations within in the female pelvic region. Their causes, prognosis, and treatment also vary.
Cysts may form because of endometriosis, pelvic inflammatory disease, previous abdominal or pelvic surgery, and trauma. Rarely, a cyst will form in or around the appendix, usually when an appendectomy is involved. The fallopian tubes may become cystic when dilated with fluid, pus, or blood, caused by adhesions from inflammatory disease, tubal ectopic pregnancy, or endometriosis.
A uterine lesion called a leiomyoma — a benign, smooth muscle tumor — is the most common gynecologic tumor, affecting 40% of women over the age of 35. Adenomyosis is another common, benign condition affecting menstruating women, especially those who have had more than one child.
Several types of cysts may form outside the peritoneum, including spinal meningeal cysts, retrorectal developmental cysts, lymphoceles, cystic lymphangiomas, and hemangiomas.
Finally, pelvic abscesses may result from appendicitis, diverticulitis, inflammatory bowel disease, postoperative anastomotic leak, infected hematoma, lymphocele, seroma, and urinoma.
Multiple types of imaging are available and necessary, along with a physical examination and thorough medical history, to determine the exact nature of the abdominal mass and thus to determine the best course of treatment.