If you have spent years being told that painful periods are “just something women go through,” getting an endometriosis diagnosis can feel like finally putting a name to something your body has been trying to tell you.
But there is no single blood test that simply says “Yes, you have endometriosis.”
Diagnosis usually involves putting several pieces together: your symptoms, menstrual history, examination where appropriate, imaging and, in selected situations, laparoscopy. 1 2 3
And one of the most important things to know is this:
A normal scan does not automatically mean you don’t have endometriosis. 1 2
Quick Answer
There is no single test that can definitively diagnose endometriosis. Diagnosis usually brings together your symptoms and menstrual history, clinical assessment, imaging such as ultrasound or MRI, and, in selected situations, laparoscopy. 1 2 3
A normal ultrasound or MRI does not automatically mean you do not have endometriosis. Some forms, particularly superficial disease, may not be visible on imaging. 1 2
From the Doctor’s Desk
Endometriosis can take time to diagnose because there is no single test that can answer every question. Your symptoms and their pattern are important pieces of the diagnostic process, and imaging can provide valuable information about where disease may be present.
I encourage women not to dismiss persistent or cyclical pain simply because an initial scan is normal. A normal scan does not always exclude endometriosis, and the next step should be guided by your symptoms, examination, imaging findings and individual priorities.
It Often Starts With Your Story
Before any scan, your doctor will want to understand what your pain actually looks like.
Tell them if you experience:
- Very painful periods
- Deep pain during sex
- Pain while passing stool, particularly around your period
- Pain or burning while urinating, especially cyclically
- Heavy or unusual menstrual bleeding
- Pelvic pain outside your period
- Persistent fatigue
- Difficulty conceiving
These are among the symptoms that can raise suspicion of endometriosis. 1 2
The pattern matters just as much as the symptom.
For example:
“I get severe bowel pain only during my periods”
can be much more informative than simply saying:
“My stomach hurts.”
A period and symptom diary can therefore be genuinely useful when you see your doctor. 1 2
What happens at the first consultation?
Your doctor may ask about your menstrual cycle, pain, bowel and bladder symptoms, sexual pain, previous pregnancies or fertility treatment, family history and previous investigations.
A pelvic or vaginal examination may be offered when appropriate. It can sometimes help identify tenderness, nodules or an endometrioma, but examination alone is not accurate enough to rule out endometriosis. 1
So don’t be surprised if your doctor recommends imaging even when the examination feels completely normal.
The First Scan: Usually Ultrasound
For someone with suspected endometriosis, ultrasound is an important part of the diagnostic work-up.
Current NICE guidance recommends offering a transvaginal ultrasound to people with suspected endometriosis, even when the pelvic or abdominal examination is normal. It can help identify ovarian endometriomas, deep endometriosis and other causes of pelvic symptoms. 2 3 5
A transvaginal ultrasound involves placing a slim ultrasound probe into the vagina to obtain detailed images of the pelvic organs.
It may feel uncomfortable, particularly if you already have pelvic pain, but it should not be something you are expected to simply endure. Tell the sonographer if you are uncomfortable.
If a transvaginal scan is not suitable or you do not wish to have one, a transabdominal pelvic ultrasound may be considered. 2
One important detail: not every ultrasound is equally informative
A routine pelvic ultrasound and a specialist endometriosis ultrasound are not necessarily the same thing.
When deep endometriosis is suspected, specialist ultrasound performed and interpreted by someone experienced in gynaecological imaging can provide much more useful information. 2
What About an MRI?
MRI is not automatically the first test everyone needs.
It can be particularly useful when deep endometriosis is suspected, helping doctors understand where disease may be located and how extensive it might be. NICE recommends specialist pelvic ultrasound or MRI for suspected deep endometriosis. 2 3
MRI does not involve radiation.
You lie inside the scanner while detailed images of the pelvis are taken. It can be noisy and may feel enclosed, but there is no internal probe.
For some women, MRI is also useful for planning treatment or surgery.
What If the Ultrasound or MRI Is Normal?
This is probably the most important part of the article.
Normal imaging does not completely rule out endometriosis.
Ultrasound and MRI are particularly useful for detecting certain forms of endometriosis, including ovarian and deep disease. But superficial peritoneal endometriosis may not be visible. 1 2 3
So if your symptoms strongly suggest endometriosis but your scan says “normal,” that does not mean:
“Your pain isn’t real.”
Your doctor may consider your symptoms, alternative diagnoses, response to treatment and whether further specialist assessment is appropriate.
ESHRE specifically recommends considering further diagnostic steps when imaging is negative but suspicion remains. 1
Is There a Blood Test for Endometriosis?
At present, no blood test is recommended as a definitive diagnostic test for endometriosis. 1 2 3
You may hear about CA-125 or newer blood, urine, saliva or other biomarker tests advertised online.
CA-125 can sometimes be elevated in endometriosis, but it is not reliable enough to diagnose or rule it out. NICE specifically advises against using serum CA-125 to diagnose endometriosis, while ESHRE recommends against using biomarkers in blood or other biological samples for diagnosis. 1 2 3
So if someone tells you: “Just get a CA-125 and you’ll know.” —be cautious.
Where Does Laparoscopy Fit In?
Laparoscopy is a minimally invasive surgical procedure performed under anaesthesia. A surgeon makes small abdominal incisions and uses a camera to look directly at the pelvis.
It can allow the surgeon to see endometriotic lesions that imaging may not detect and, when appropriate and consented for, treatment can sometimes be performed during the same procedure. 1 2
But laparoscopy is not automatically required for every woman with suspected endometriosis.
Current guidelines have moved away from the idea that every diagnosis must begin with surgery. Imaging and clinical assessment can sometimes provide enough information to move forward with treatment. Laparoscopy may be considered when imaging is negative or inconclusive, symptoms persist, or empirical treatment is unsuccessful or inappropriate. 1 2
If laparoscopy is performed, suspected lesions may be biopsied for histological confirmation. Importantly, negative histology does not completely exclude endometriosis. 1 2
So, What Does a Typical Diagnostic Journey Look Like?
It may look something like this:
Symptoms → detailed history → examination where appropriate → ultrasound → specialist ultrasound/MRI if indicated → treatment or further investigation → laparoscopy in selected cases
It isn’t necessarily a straight line. Two women with the same symptoms may need completely different investigations. And sometimes treatment begins before absolute surgical confirmation, depending on the symptoms, priorities and clinical situation. 1 4
The Goal Isn’t Just to Get a Label
The purpose of diagnosis is not simply to put “endometriosis” on your medical record.
It is to understand:
- Where might the disease be?
- How much is it affecting you?
- Is fertility a priority?
- What symptoms need treatment?
- And what approach makes sense for you?
If you have persistent, disabling or cyclical pelvic pain, painful periods, painful sex, bowel or bladder symptoms around menstruation, or unexplained difficulty conceiving, you deserve to be taken seriously. 2 4
You don’t need to prove that your pain is severe enough. Your symptoms are the starting point of the investigation.
Key Takeaways
- Endometriosis is diagnosed using a combination of symptoms, clinical assessment, imaging and, in selected cases, laparoscopy. 1 2
- A transvaginal ultrasound is an important first-line investigation for suspected endometriosis. 2
- Specialist ultrasound or MRI can be particularly useful when deep endometriosis is suspected. 2
- A normal ultrasound or MRI does not completely rule out endometriosis, especially superficial disease. 1 2
- CA-125 and other blood biomarkers are not recommended as definitive diagnostic tests. 1 2
- Laparoscopy may be considered when symptoms persist despite negative or inconclusive imaging or when empirical treatment is unsuccessful or inappropriate. 1
- You do not need to have surgery simply to prove that your pain is real.
References
[1] Becker CM, et al. ESHRE guideline: endometriosis. Human Reproduction Open. 2022;2022(2):hoac009.ESHRE — Endometriosis Guideline
[2] National Institute for Health and Care Excellence. Endometriosis: diagnosis and management (NG73). Updated 2024.NICE — Endometriosis: Diagnosis and Management
[3] National Institute for Health and Care Excellence. Evidence review: Diagnosing endometriosis. Updated 2024.NICE — Evidence Review: Diagnosing Endometriosis
[4] European Society of Human Reproduction and Embryology. Endometriosis: Patient Information.ESHRE — Patient Information
[5] National Institute for Health and Care Excellence. Our updated guideline to improve the diagnosis of endometriosis.2024.NICE — Updated Endometriosis Diagnosis Guidance