According to the American Society for Reproductive Medicine (ASRM), up to 10% of all women suffer from endometriosis. However, the disease does not always manifest itself in the same way. While some women experience all or some of the symptoms, others may experience only a few or no symptoms at all. The same is true for infertility, which affects some but not all patients. The manifestation or severity of the symptoms is not linearly correlated to the extent of the disease.
Many classification systems have been created to explain the different 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.
- 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 and IV — 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.