While a working diagnosis of endometriosis might be made from symptoms or other tests, a definitive diagnosis is only made by surgery with biopsy. It is important for your surgeon to have knowledge about all the different appearances of endometriosis as well as all the different areas it can be found (see “Appearances of Endometriosis“). It is also more efficient and cost-saving for your surgeon to be able to treat at the same time when a diagnostic surgery is performed (see “Why Surgery“).
“Your doctor or nurse might suspect that you have endometriosis based on your symptoms of pelvic pain or painful menstrual periods. However, the only way to know for sure if you have endometriosis is to have surgery so a doctor can actually see and biopsy the abnormal tissue. Endometriosis cannot be diagnosed by ultrasound, x-ray, or other noninvasive methods.” – https://www.uptodate.com/contents/endometriosis-beyond-the-basics
Reference
Jose, C., Fausto, A., & Antonio, L. (2018). Laparoscopic Enhanced Imaging Modalities for the Identification of Endometriosis Implants a Review of the Current Status. MOJ Womens Health, 7(1), 00160. DOI: 10.15406/mojwh.2018.07.00160