An ovarian mass, also known as an ovarian adnexal mass, is a tissue mass in the adnexa of the uterus, which refers to the space occupied by the uterus, ovaries and fallopian tubes. These can take the form of different types of malignant or benign masses. In premenopausal women, most adnexal masses are caused by ectopic pregnancy, ovarian cysts, tumors, polycystic ovaries and abscesses. After menopause, more likely causes include fibroid tumors, fibromas and malignant tumors. The most common locations for an adnexal mass to grow are in a fallopian tube or ovary.

The majority of adnexal masses are benign, but diagnosis of an adnexal mass is difficult because there are many forms that a mass can take. Even in a healthy ovary, follicular cysts can develop half a dozen times in a single year. Most of the time, these cysts develop, shrink and disappear within the course of a single menstruation cycle. In some cases, however, they grow larger and remain in the ovary, fallopian tube or uterus.

Often, a definitive diagnosis of an ovarian mass is never reached.  Therefore, an ovarian mass must be carefully evaluated using information obtained from ultrasound and other tests in order to determine whether it is likely to be malignant or benign. Another common factor with these types of masses is that most are asymptomatic and are discovered during a routine pelvic or other examination rather than because they cause pain or discomfort.

Small, asymptomatic masses generally do not require any treatment. Instead, these masses are monitored with tests and pelvic examinations. In cases where the mass is large or is causing symptoms, it is surgically removed. Surgery generally is more aggressive and involves the removal of more tissue when the mass is malignant. This is important to prevent recurrence or spread of the cancer. Surgical removal of a malignant tumor is likely to be followed up with a course of chemotherapy treatments.