Endometriosis is often classified as mild, moderate or severe or recorded as stage one to four.
Mild or stage one endometriosis appears as small patches or surface lesions across the pelvic cavity.
Moderate or stage two appears as larger, more widespread disease which begins to infiltrate tissue and is often found on the ovaries, uterosacral ligaments, or pouch of Douglas. There can also be significant scarring and adhesions.
Severe or stage four endometriosis affects most of the pelvic organs, often with the distortion of anatomy and adhesions.
While these stages of endometriosis are accepted worldwide, the extent of endometriosis is not generally related to the symptoms that are experienced.