Stages of Endometriosis

What is endometriosis?

A woman’s uterus is lined with endometrial tissue that is shed once a month during the menstrual cycle. Endometriosis is a chronic, painful medical condition that occurs when endometrial-like tissue grows outside the uterine cavity. The ovaries, Fallopian tubes, and the tissue lining the pelvis are commonly involved. Pain associated with endometriosis is usually more severe during menstrual periods as the tissue responds to changing hormones and thickens and bleeds but has no way to exit the body. In severe cases, endometriosis can cause infertility.

Stages of endometriosis

Endometriosis is categorized into four stages; however, it does not always move directly from one stage to the next. It can also improve or worsen with time. Some cases are more severe than others, however, the reason for this is unknown. The stages are based on criteria involving location, amount, depth, and size of endometrial tissue. Specific staging criteria include the spread of the endometrial tissue, pelvic involvement, pelvic adhesions, and blockage of the Fallopian tubes. The stages do not necessarily represent pain levels; for example, a woman in stage 1 may experience severe pain while a woman in stage 4 may not experience any pain.

Stage 1 (Minimal)

Scar tissue is minimal in this stage. Endometrial implants are few and small. These lesions may be starting to grow on internal organs or on the tissue lining the pelvis or abdomen. Inflammation may also appear around the pelvic cavity.

Stage 2 (Mild)

Scar tissue increases and more endometrial implants are present than in stage 1. The light lesions begin growing deeper into the tissue surrounding the uterus, on one or both ovaries, and into the pelvic lining.

Stage 3 (Moderate)

Endometrial implants become numerous and deep. Adhesions increase and can be found on the ovaries and pelvic lining during this stage. The size of ovarian cysts ranges from small to large.

Stage 4 (Severe)

Large cysts exist on one or both ovaries. Endometrial implants are widespread and include the pelvic lining. Adhesions are deep and thick. Lesions may be present on the Fallopian tubes and bowels.