How Is Endometriosis Diagnosed? Tests and Evaluation

Diagnosing endometriosis is not always straightforward. Symptoms such as painful periods, chronic pelvic pain, pain during sex, bowel discomfort, urinary symptoms, or difficulty becoming pregnant can occur with several different conditions. At the same time, some people with endometriosis may have few or no obvious symptoms.

Evaluation usually begins with a detailed discussion of symptoms and medical history, followed by a physical examination and imaging when appropriate. 

Depending on the findings and how strongly endometriosis is suspected, further specialist assessment or laparoscopy may be considered. If you are looking for a broader understanding of the condition and its management, you can explore the Endometriosis Treatment guide.

Why Can Endometriosis Be Difficult to Diagnose?

Endometriosis does not have one simple test that can identify every form of the disease. Its symptoms can overlap with conditions such as adenomyosis, uterine fibroids, pelvic inflammatory disease, irritable bowel syndrome, urinary conditions, and other causes of pelvic pain.

The location of endometriosis also matters. Larger ovarian endometriomas and some forms of deep endometriosis can often be identified on imaging, while small or superficial lesions may not be visible.

This means that a normal examination or scan does not necessarily rule out endometriosis, particularly when symptoms remain strongly suggestive of the condition.

Step 1: Medical History and Symptoms

The diagnostic process usually starts with a detailed discussion about your symptoms. Rather than looking at one symptom in isolation, a healthcare professional may consider how your symptoms relate to your menstrual cycle and how they affect your everyday life.

Questions may include:

• How painful are your periods?
• When did the pain begin?
• Does the pain occur only during menstruation or at other times as well?
• Do you experience pain during or after sexual intercourse?
• Do you have pain when passing stool or urinating, particularly around your period?
• Have you experienced persistent pelvic or lower back pain?
• Do you have heavy or irregular menstrual bleeding?
• Have you had difficulty becoming pregnant?
• Has anyone in your immediate family been diagnosed with endometriosis?
• Have previous treatments improved or failed to improve your symptoms?

Keeping a record of pain, bleeding, bowel or bladder symptoms, and their relationship to your menstrual cycle can make these discussions more useful.

Step 2: Physical and Pelvic Examination

A physical examination may be performed when endometriosis is suspected. Depending on the situation, this can include an abdominal examination and a pelvic examination.

A pelvic examination may help identify findings such as pelvic tenderness, reduced movement of pelvic organs, an enlarged or tender area, or other abnormalities that may suggest endometriosis.

However, a normal examination does not exclude endometriosis. Some forms of the disease may not produce detectable physical findings, particularly when the lesions are small or located in areas that cannot be assessed easily during an examination.

If an internal pelvic examination is not appropriate or is declined, other forms of assessment can still be considered.

Step 3: Transvaginal Ultrasound

Transvaginal ultrasound is an important part of the evaluation of suspected endometriosis. It uses an ultrasound probe placed in the vagina to produce images of the pelvic organs. It may help identify:

• Ovarian endometriomas
• Some forms of deep endometriosis
• Changes involving the bowel, bladder, or ureters
• Other pelvic abnormalities that could explain symptoms

What if the ultrasound is normal?

A normal ultrasound does not automatically mean that you do not have endometriosis. Ultrasound is better at detecting some forms of endometriosis than others. Superficial endometriosis, in particular, may remain invisible on imaging. If symptoms continue and clinical suspicion remains high, further evaluation may still be appropriate.

Step 4: Pelvic MRI

MRI may be recommended when deeper or more extensive endometriosis is suspected. It provides detailed images of the pelvic structures and can help assess the location and extent of deep endometriosis. MRI may be particularly useful when there is concern that endometriosis involves structures such as:

• The bowel
• The bladder
• The ureters
• The tissues behind or around the uterus
• Other areas of the pelvis

MRI is not necessarily required for everyone with suspected endometriosis. The decision depends on symptoms, previous examination and ultrasound findings, and whether deep disease needs to be mapped before further management.

Step 5: Diagnostic Laparoscopy

Laparoscopy is a minimally invasive surgical procedure that allows a surgeon to directly examine the pelvic organs through a camera inserted through a small abdominal incision.

It may be considered when:

• Symptoms strongly suggest endometriosis but imaging has not provided an explanation.
• Ultrasound or MRI results are normal but significant symptoms continue.
• Previous medical treatment has not adequately controlled symptoms.
• There is a need to directly assess suspected endometriosis and potentially treat it during the same procedure.

During laparoscopy, the surgeon systematically examines the pelvic structures for signs of endometriosis. If suspicious tissue is found, a biopsy may be taken for laboratory examination.

Does a Biopsy Confirm Endometriosis?

A biopsy involves removing a small sample of tissue and examining it under a microscope. When tissue suspected to be endometriosis is identified during laparoscopy, histological examination can help confirm the diagnosis.

However, a negative biopsy does not always completely exclude endometriosis. The result needs to be interpreted alongside the surgical findings, symptoms, imaging, and overall clinical picture.

Can You Have Endometriosis Even If All Tests Are Normal?

Yes. This is one of the most important points to understand about endometriosis diagnosis. Ultrasound and MRI can be very useful, particularly for identifying endometriomas and deep endometriosis, but they cannot reliably detect every type of endometriosis. Small or superficial lesions may not appear on imaging.

Therefore, persistent symptoms should not automatically be dismissed because a scan is normal. Further assessment may be appropriate when the overall clinical picture continues to suggest endometriosis.

What Happens After Endometriosis Is Diagnosed?

Diagnosis is not simply about assigning a stage or label to the condition. The findings need to be considered alongside your symptoms, fertility plans, and personal priorities.

Once endometriosis is identified or strongly suspected, your healthcare professional may discuss options such as medical treatment, monitoring, surgery, or fertility-focused care, depending on your individual circumstances.

The extent of disease seen on imaging or during surgery does not always correspond directly to the severity of pain. For this reason, treatment decisions should not be based on imaging findings alone.

Endometriosis Diagnosis: What Each Test Can and Cannot Tell You

The Bottom Line

Endometriosis is diagnosed through a combination of symptoms, medical history, examination, imaging, and, in selected cases, laparoscopy and tissue examination. No single test can reliably identify every form of the disease.

A normal examination or scan does not necessarily end the evaluation when symptoms remain strongly suggestive of endometriosis. The goal of diagnosis is to understand what is causing your symptoms, identify the location and extent of disease when possible, rule out other conditions, and provide enough information to guide appropriate treatment.