Diagnosing endometriosis: from imaging pathways to complex cases

From clinical examination to MRI: the diagnostic pathway

The diagnostic pathway begins with a detailed discussion about pain, its timing, intensity, and other associated symptoms. This interview, combined with a gynecological exam, allows for a clinical suspicion to be established even before imaging tests are performed.

Endovaginal pelvic ultrasound is the first-line examination. It can detect ovarian endometriomas and certain deep lesions, provided it is performed by an operator specifically trained in endometriosis. For patients who cannot undergo this exam (notably those who are virgins), a pelvic MRI is prescribed from the outset.

Pelvic MRI is prescribed as a follow-up to assess the precise location of lesions, their depth, and their extension to neighboring organs. It is essential in the preoperative assessment of deep endometriosis. Like ultrasound, its sensitivity depends on the experience of the radiologist interpreting it: two readers may reach different conclusions from the same images, depending on their level of specialization.

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When imaging is inconclusive: additional options

Ultrasound and MRI have their limitations. Superficial lesions (small peritoneal endometriosis) may not be visible, even when performed under optimal conditions. Normal imaging therefore does not rule out endometriosis when symptoms are suggestive; in such cases, one must rely on the clinical examination.

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Expert radiologist image review

Before considering any additional testing, having existing images (MRI or ultrasound) reviewed by a radiologist specializing in pelvic endometriosis imaging can change the initial interpretation and resolve diagnostic uncertainty without the need for a repeat scan. This step is particularly relevant when the initial assessment was performed at a center not specialized in this condition.

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The Endotest® saliva test

Endotest® is a saliva test that analyzes specific biomarkers to detect endometriosis without the need for surgery. It is indicated in specific situations: symptoms clinically suggestive of endometriosis, inconclusive imaging results, and following consultation with a specialized center. As of 2024, this test is covered by the French national health insurance system under the HAS innovation package.

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Laparoscopy: when is it still indicated?

Laparoscopy (a surgical procedure to directly visualize lesions in the pelvic cavity) is no longer the standard diagnostic test. It remains indicated in specific situations: negative or inconclusive imaging, a positive Endotest® result, and debilitating symptoms that significantly impair quality of life. It is often performed during the same operative session as the surgical treatment of the identified lesions.

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Deep endometriosis: specialized preoperative assessment tests

When deep endometriosis involving adjacent organs is suspected, additional tests are prescribed to plan for potential surgery. These are not performed as a first-line measure, but rather as part of a referral to an expert center.

• Water-contrast CT colonography: indicated when digestive involvement is suspected (pain during bowel movements linked to the menstrual cycle, persistent bowel transit issues). It identifies the location and extent of lesions on the rectum or sigmoid colon. ‍
• Uroscan or uro-MRI: prescribed when ureteral or bladder involvement is suspected, particularly if urinary symptoms (hematuria, dysuria) persist during menstruation. ‍
• Rectal endoscopic ultrasound: for deep forms with recto-sigmoid involvement, this examination performed by an experienced gastroenterologist determines the depth of infiltration and guides the surgical strategy.

These examinations are part of a multidisciplinary consultation (gynecologist, specialized radiologist, digestive surgeon) within an endometriosis expert center. Dedicated regional networks, such as EndAura in Auvergne-Rhône-Alpes or EndoSud in PACA, organize this coordinated care.