From my understanding, the only way to confirm is the internally visually confirm that endometriosis is present. Endometriosis cannot be seen on ultrasound or mri - in some cases it can be highly suspected bc scarring / adhesions can cause organ displacement or you can see large endometriomas (cyst made from endometriosis tissue) but it will be documented as a potential endometrioma or hemorrhagic cyst because it still can’t be confirmed that it is in fact endometriosis without visually seeing it. Sorry you’re going through this. My doctors refused to do surgery to confirm and now all my organs are scarred together and I wish someone listened to me and confirmed my diagnosis sooner

I can't answer why but I agree that it is ridiculous and unfair. I had the discovery surgery just to get told "yes you have it" and had to have the excision surgery 3 weeks later. Such a waste.