A classification system has been created to classify the stages of endometriosis, but the most common is a numeral classification system divided into four stages. The four stages of endometriosis are equivalent to minimal, mild, moderate, or severe endometriosis, and the majority of patients are included in the two first categories. The classification is made during the same surgical procedure used to confirm the diagnosis, which is called a laparoscopy. During the surgery, a surgeon makes small incisions in the abdomen to observe the reproductive organs, intestines, and other surfaces.
- Stage I — minimal endometriosis is characterized by isolated implants and no significant adhesions
- Stage II — mild endometriosis by superficial implants less than 5 cm in aggregate without significant adhesions.
- Stage III — moderate endometriosis and IV — severe endometriosis consists of multiple implants and scarring around the tubes and ovaries or on multiple implants, including large ovarian endometriomas with thick adhesions, respectively.