Endometrial implants that are small and not widespread are considered minimal or mild endometriosis. Moderate endometriosis means that larger implants or more extensive scar tissue is present. Most often, the symptoms of endometriosis start years after menstrual periods begin. As time passes, those symptoms tend to gradually increase as the endometriosis areas increase in size. After menopause, the abnormal implants shrink away and much of the symptoms subside.
Endometriosis is considered one of the three major causes of female infertility.
However, unsuspected or mild endometriosis is a common finding among infertile women and how this type of endometriosis affects fertility is still not clear. Rarely, the irritation caused by endometrial implants may progress into infection or abscesses causing pain independent of the menstrual cycle. Alas, nothing about endometriosis is simple. The cause of endometriosis is unknown. Another theory suggests that endometriosis may be a genetic process or that certain families may have predisposing factors to endometriosis.