Each women experiences stages of endometriosis differently. Some women may manifest extensive endometrial tissues in their body but feel little or no pain at all, while other women may only be in the early stage of endometriosis but have excessive pain.

Mild endometriosis - this stage of endometriosis is characterized by increasing numbers of implants, which are small, flat patches of endometrial tissue growing outside of their normal location. These implants are commonly found in the same area as during the minimal stage of endometriosis but are usually deeper.  Although mild endometriosis is associated with infertility in some women, many fertile women are diagnosed with mild endometriosis.

Moderate endometriosis - during this stage of endometriosis, many implants and endometriotic cysts are present and can affect ovary function, causing scar tissues.  Adheresion is also present. Includes "chocolate cysts" of endometriosis may be smaller than a pea or larger than a grapefruit, located within the ovary.

Severe endometriosis - severe endometriosis is typically characterized by intensive perionreal implants, large endometromas and dense adheresion that can cause pelvic scarring and distortion of pelvic anatomy. The tubes can become damaged or blocked and the ovaries often contain cysts of endometriosis (endometriomas) and may become adherent to the uterus, bowel or pelvic side wall. Any of these anatomic distortions can result in infertility.