The goal of this observational study is to identify diagnostic and prognostic biomarkers for endometriosis using menstrual blood, an easily accessible yet overlooked biological fluid in women of reproductive age, affected or not by endometriosis

The main questions it aims to answer are:

• are there relevant differences in the menstrual blood of women affected by endometriosis compared to women without endometriosis?
• do some of these differences disappear or lessen when the disease is treated by surgery? Participants will answer questions relevant to endometriosis and provide menstrual blood 1 to 3 times (self-collected with a menstrual cup). A subgroup of participants affected by endometriosis that will undergo surgery for their regular care will provide menstrual blood before and after their surgery.

Researchers will compare the menstrual blood of women with and without endometriosis, and before and after surgery to see if they can identify significant differences.

Inclusion Criteria:

For all participants:

Women 18-45 of age who

• Have their period
• Have given their written consent
• Have already used a menstrual cup as a method of hygienic protection
• Residing or working in Ile de France (Paris Metropolitan area, France)

For participants with endometriosis:

• diagnosis of endometriosis established by surgery or imaging (ultrasound and/or MRI)
• presence of one or more painful symptoms > 3 on a visual scale (dysmenorrhea and/or dyspareunia and/or chronic pelvic pain) and/or infertility
• for the surgery subgroup: planned surgery in the next 3 months

For participants without endometriosis:

• painful symptoms < or equal to 3 on a visual scale (for dysmenorrhea and dyspareunia and chronic pelvic pain),
• absence of intense period pain in adolescence (leading to taking pills to control this pain and/or peri-menstrual school absenteeism)

Exclusion Criteria:

For all participants:

• Autoimmune diseases
• Chronic diseases other than endometriosis (diabetes, hypertension)
• A person who is the subject of a judicial safeguard measure (by declaration)
• Infectious diseases (HIV, HBV, if known)
• History of menstrual toxic shock syndrome

For patients with endometriosis:

• endometriosis surgery within the last 3 months.

Women 18-45 of age with periods