Potentially disabling and difficult to diagnose, endometriosis has recently been the subject of highly intriguing research. French researchers sought to determine whether menstrual blood could serve as a potential source of biomarkers for endometriosis for diagnostic purposes.
What is endometriosis?
Affecting about 10% of women, endometriosis is a gynecological inflammatory and chronic disease. It is defined by the presence of tissue similar to the endometrium—the lining of the uterus—outside the uterine cavity.
During each menstrual cycle, the normal endometrium swells under the influence of hormones and then breaks down if there is no pregnancy. In women with endometriosis, the cells located outside the uterus react in exactly the same way. They grow and bleed each month, but this blood has no way to be expelled from the body. However, these small internal hemorrhages trigger inflammatory reactions, irritations, and eventually form lesions, cysts or adhesions of tissue that bind the organs together.
It should be noted that endometriosis is difficult to diagnose due to the varied nature of its symptoms, the normalization of menstrual pain and the complexity of medical imaging. On average, it takes between 7 and 10 years to obtain an official diagnosis.
Five “biomarker candidates” identified
On September 10, 2026, Inserm published a statement describing a study that appeared in June in the journal BMC Medicine. A research team from Inserm, the Pasteur Institute, Lyon 1 University and the Léon-Bérard Center carried out work on the potential of menstrual blood in the screening of endometriosis. This represents a major scientific development, as a source of hope for millions of women.
In practice, the researchers analyzed the cells and molecules present in the menstrual blood of about ten women. Five specific genes – TIMP2, AKR1C2, DMBT1, FERMT1 and KCNK5 – were defined as “biomarker candidates”, whose expression is altered in patients with endometriosis compared with healthy individuals. Thus for the researchers, menstrual blood emerges as a unique biological sample, much richer in information about uterine health than ordinary blood.
“Menstrual blood as a whole is heterogeneous; from one sample to another, varying quantities of endometrial cells can be found. We therefore knew we could not identify all markers in the global RNA, especially since this pilot study used only a small number of samples. However, the identification of these five markers allowed us to verify that some signals are robust enough to emerge despite these variations and invite confirmation of these results with larger cohorts.”, reads the press release.
More extensive work ahead
Current methods sometimes require complex imaging tests or exploratory surgeries such as laparoscopy. Here, the technique is non-invasive because the sampling is entirely painless and simple, taken directly from the menstrual fluid. According to the study authors, a test based on menstrual blood could enable very early screening, especially during adolescence, before the lesions cause too much damage.
Despite encouraging results, the French study remains small in scale, having targeted deep forms of endometriosis. Thus, no diagnostic test based on these results is yet commercialized. For scientists, the next logical step will be to conduct clinical trials on much larger cohorts of patients to validate the effectiveness of the five markers across all forms of the disease.
