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Published on: 12/22/2025

How to diagnose endometriosis?

Endometriosis is diagnosed through a detailed history and pelvic exam, then imaging with transvaginal ultrasound to look for ovarian endometriomas and MRI when deep involvement is suspected or ultrasound is unclear. Blood tests like CA-125 may support the picture but cannot confirm it. Definitive confirmation requires diagnostic laparoscopy with biopsy, which can also allow treatment; there are several factors to consider about which test to use when, when surgery is appropriate, and when to see a specialist. See below for important details that could affect your next steps.

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Explanation

How to Diagnose Endometriosis

Endometriosis is a condition where tissue similar to the lining of the uterus grows outside the uterus, commonly on the ovaries, fallopian tubes, pelvic lining and sometimes other organs. It affects up to 10% of women of reproductive age and can cause pain, heavy periods, infertility and other symptoms. Early and accurate diagnosis is key to managing symptoms, preserving fertility and improving quality of life. Below is an overview of how endometriosis is diagnosed, based on current guidelines and imaging studies.

Clinical Evaluation
A thorough medical history and physical exam are the first steps in diagnosing endometriosis. Your doctor will ask about symptoms, menstrual patterns and reproductive goals. Key points include:

  • Symptoms to report

    • Pelvic pain (during menstruation, intercourse, bowel movements or urination)
    • Heavy or irregular menstrual bleeding
    • Infertility or difficulty conceiving
    • Fatigue, bloating or gastrointestinal upset
  • Physical (pelvic) exam

    • The doctor may gently press on areas of your pelvis to check for tenderness, nodules or masses.
    • Sometimes, deep endometriotic lesions can be felt as firm nodules behind the uterus or in the vaginal wall.

Keep in mind that a normal pelvic exam does not rule out endometriosis, especially for deep or small implants.

Imaging Techniques
Imaging can help locate endometriotic lesions, guide treatment and rule out other conditions. Two main tools are transvaginal ultrasound (TVUS) and magnetic resonance imaging (MRI).

  1. Transvaginal Ultrasound (TVUS)
    • First-line imaging test: easily available, non-invasive, no radiation.
    • Best for detecting ovarian endometriomas (blood-filled “chocolate cysts”) and some deep lesions.
    • According to Guerriero et al. (2014), TVUS has high specificity (nearly 100%) for endometriomas and good sensitivity (79–85%).
    • Limitations: may miss small peritoneal implants or lesions outside the pelvis.

  2. Magnetic Resonance Imaging (MRI)
    • Second-line test when TVUS is inconclusive or deep endometriosis is suspected.
    • Provides detailed images of soft tissues, showing the size and location of implants.
    • According to Guerriero et al., MRI sensitivity and specificity for deep pelvic endometriosis are both around 90%.
    • Useful for surgical planning—helps map lesions on bowel, bladder, ureters and ligaments.

  3. When to Use Each Modality

    • TVUS is ideal if you have pelvic pain and suspected ovarian cysts.
    • MRI is recommended if deep infiltrating endometriosis (e.g., rectovaginal, bladder involvement) is suspected, or if TVUS results are unclear.
    • Combining both tests can increase diagnostic accuracy.

Blood Tests
There is no single blood test that definitively diagnoses endometriosis. However, some markers can support the clinical picture:

  • CA-125: often elevated in moderate to severe cases, but not specific (it can rise in fibroids, pelvic infection, pregnancy).
  • Other biomarkers (e.g., interleukins, growth factors) are under study but not yet widely used.

The Gold Standard: Diagnostic Laparoscopy
While clinical evaluation and imaging can strongly suggest endometriosis, laparoscopy remains the gold standard. This minimally invasive surgery allows direct visualization and biopsy of lesions.

• Procedure
• Performed under general anesthesia through small incisions in the abdomen.
• A thin scope (laparoscope) with a camera examines pelvic organs.
• Surgeon can identify implants, adhesions and cysts, then remove or biopsy them.

• Histological confirmation
• Tissue samples are examined under a microscope to confirm endometrial-type glands and stroma.
• Confirms the diagnosis and rules out other pathologies (e.g., ovarian tumors).

• Benefits

  • Direct treatment: removal or ablation of lesions during the same procedure can relieve pain and improve fertility.
  • Precise staging: helps plan further medical or surgical therapy in line with ESHRE guidelines.

When to Consider Laparoscopy
Medical guidelines (ESHRE 2014) recommend laparoscopy when:

  • Symptoms are severe or debilitating despite medical therapy.
  • Infertility evaluation is underway.
  • Imaging suggests deep or extensive disease requiring surgical planning.

Non-Invasive Symptom Assessment
If you suspect endometriosis but aren’t ready for clinical tests, you might try a free, online symptom check for endometriosis. While not a substitute for professional evaluation, it can help you track symptoms and decide when to seek medical care.

Differential Diagnosis
Other conditions can mimic endometriosis symptoms. Your doctor will consider and rule out:

  • Pelvic inflammatory disease (PID)
  • Ovarian cysts or tumors
  • Uterine fibroids
  • Interstitial cystitis or bladder pain syndrome
  • Irritable bowel syndrome (IBS)

Management decisions often depend on accurate diagnosis and ruling out these alternatives.

Putting It All Together: A Step-By-Step Approach

  1. Report symptoms to your doctor. Keep a pain diary detailing timing, severity and triggers.
  2. Undergo a pelvic exam to check for tenderness, nodules or masses.
  3. Have transvaginal ultrasound to look for ovarian cysts and some deep lesions.
  4. If needed, get an MRI to map deep implants and guide treatment.
  5. Consider CA-125 or other blood tests to support the diagnosis (not definitive).
  6. If non-invasive tests suggest endometriosis or if symptoms persist, discuss diagnostic laparoscopy.
  7. During laparoscopy, have suspicious lesions biopsied for histological confirmation.
  8. With a confirmed diagnosis, follow individualized treatment based on lesion type, severity of symptoms and fertility goals (medical therapy, surgery or both).

When to See a Specialist
Endometriosis can be complex, especially if you have:

  • Severe or worsening pelvic pain
  • Bowel or bladder involvement
  • Infertility after a year of trying to conceive
  • Large ovarian cysts (>4 cm) or complex masses
    Seek a gynecologist with expertise in endometriosis or a specialized pelvic pain center.

Key Takeaways

  • Early recognition and diagnosis improve outcomes and fertility preservation.
  • Clinical evaluation, imaging (TVUS, MRI) and laparoscopy work together for accurate diagnosis.
  • Laparoscopy with histology remains the gold standard.
  • Don’t ignore persistent pelvic pain, heavy periods or fertility issues—talk to your doctor.
  • Try a free, online symptom check for endometriosis to track your symptoms.

Always consult a healthcare professional for anything that could be life-threatening or serious. If you experience sudden, severe abdominal pain, heavy vaginal bleeding, fever or signs of infection, seek immediate medical attention.

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