It is measured through a variety of things. After surgery they should tell you what stage it is. Here is a link to help
http://www.endo-resolved.com/endometriosis_stag...

Hey MRI scan should help but going in having look is the most accurate way

I was told right after my laparoscopy by my gynecologist. have a look online at endo stages as well as images it explains. Go back to who did your surgery for clarification. Hope this helps but yes... There are different degrees of severity.

if their any reason for this, thank -you x

I was told that If you have an endometrioma that you are and automatic stage 4