Diagnosis
In short
Diagnosis is a clinical process. A scan can find some disease and miss other disease. Surgery is not always required before treatment starts. The sentences below are the ones WHO and NICE publish.
Last reviewed · Next review Jan 2027 · How we verify
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It starts with the history
WHO says a careful menstrual health history — pain, how heavy the bleeding is, and associated symptoms — can help with diagnosis. WHO also says the average time to diagnosis is between 4 and 12 years, and that long delays are common.
Ultrasound and MRI
WHO says endometriosis is diagnosed using imaging such as ultrasound, and that a clinical diagnosis may be made from symptoms and imaging tests such as ultrasound or MRI. Surgery is not necessarily required before treatment starts.
NICE says to offer a transvaginal ultrasound to people with suspected endometriosis, even if the abdominal or pelvic examination is normal. If that scan is declined or not suitable, consider a transabdominal pelvic ultrasound. NICE is explicit: do not exclude endometriosis if the examination and the ultrasound are normal. Referral may still be necessary.
For deep disease, NICE says to consider a specialist transvaginal ultrasound or a pelvic MRI to diagnose deep endometriosis and to assess how far it extends.
A blood test does not diagnose it
NICE recommendation 1.5.8 says: do not use serum CA125 to diagnose endometriosis. A raised or normal CA125 does not answer the question.
Laparoscopy
WHO says laparoscopic surgery, where tissue can be seen directly or sampled, can be recommended, and that this procedure is inaccessible to many people. It remains a way to confirm disease. It is not a requirement in every case before treatment, which is why the history and imaging matter.
Newer tests are still emerging
WHO says new tests aimed at finding endometriosis earlier include symptom checklists, blood tests, and self-tests using saliva or menstrual blood. It lists them as emerging. It does not describe a saliva or blood test as the established way to diagnose the disease. Laparoscopy and clinical assessment remain the methods WHO describes for diagnosis.
- Fact sheetWHO fact sheet, endometriosis (15 October 2025)
- GuidelineNICE NG73 recommendations