French researchers from Inserm, the Institut Pasteur, Université Claude Bernard Lyon 1, and Centre Léon Bérard have identified distinct biomarkers in menstrual blood that could pave the way for a non-invasive diagnostic test for endometriosis. Analyzing cellular components in menstrual fluid revealed specific gene activity differences between patients with the inflammatory disease and those without it, potentially offering a faster alternative to traditional imaging.
The Diagnostic Challenge of Endometriosis
According to the French Ministry of Health, endometriosis affects approximately one in ten women of childbearing age, yet patients in France still face an average diagnostic delay of seven years. Characterized by the presence of tissue similar to the endometrium outside the uterus, the chronic inflammatory condition causes severe pelvic pain, digestive issues, painful intercourse, and fertility struggles. Current clinical evaluations rely on patient histories, physical exams, pelvic ultrasounds, and MRIs conducted under guidelines updated in 2025 and labellisées by the Haute Autorité de Santé (HAS). However, these imaging techniques face limitations in detecting smaller lesions, and access remains constrained by a shortage of specialized practitioners.
Cellular Analysis of Menstrual Blood
To investigate alternative detection methods, researchers analyzed samples from a cohort of ten women aged 18 to 45, equally split between five patients with deep endometriosis and five without endometriosis. Participants collected their menstrual fluid using a menstrual cup, providing researchers direct access to uterine-derived cells without surgical intervention or tissue biopsies. Menstrual fluid contains blood cells alongside epithelial cells from the endometrial lining, stromal cells, and components of the immune system and blood vessels. By examining gene activity within these endometrial cells, the scientific team detected five biological markers that presented distinct characteristics in women with the disease compared to the control group.
Broader Diagnostic Initiatives in France
This identification of menstrual blood biomarkers aligns with broader national efforts to address diagnostic delays under France’s national strategy for endometriosis launched in 2022. The initiative prioritizes expanding research, improving care networks through specialized regional clinics, and enhancing public and professional awareness. Alongside exploratory research into menstrual fluid signatures, other non-invasive approaches are being explored, such as the deployment of saliva-based tests like the Endotest framework in defined cohorts to gather real-world data on biomarker efficacy.
If validated at a larger scale, the menstrual blood test could furnish physicians with a simple, non-invasive screening tool to flag at-risk patients and streamline referrals for specialized imaging. Researchers emphasize that such a test would complement, rather than replace, standard diagnostic tools like ultrasounds and MRIs. Beyond diagnostic applications, Inserm notes that menstrual blood is also being investigated in regenerative medicine due to the presence of endometrial stem cells capable of differentiating into multiple cell types.
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