This observational study aims at establishing the proportion of patients suffering from endometriosis and for whom an Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS) diagnosis is established.

The study participation will be offered to endometriosis patients displaying symptoms that may suggest an underlying OSAHS.

OSAHS diagnosis will be made according to standard of care practice and patients will be followed up to 12 months after initiating the OSAHS treatment to fill in questionnaires assessing the impact of OSAHS treatment on various endometriosis-related symptoms

The overall prevalence of endometriosis varies between 1% and 8% depending on the studies, and endometriosis would affect approximately one in 10 women in France. In 2022, A report was submitted to the President of the French Republic for the development of a national strategy to fight against endometriosis, proposing in particular the development of a national epidemiological database and an "easily identifiable and accessible diagnosis pathway throughout the territory".

The experience at the investigational site has led to note a significant prevalence of obstructive sleep apnea hypopnea syndrome (OSAHS) in the population of patients with endometriosis. There are no published studies on the relationships between OSAHS and endometriosis. However, intermittent hypoxemia and endothelial dysfunction are two important consequences of OSAHS that may be related to endometriosis. Moreover, it is now accepted that OSAHS is correlated with painful bladder syndrome (interstitial cystitis) and the relationship between endometriosis and a decrease in sleep quality as well as chronic fatigue syndrome has also been demonstrated.

Finally, the benefit of Continuous Positive Airway Pressure (CPAP) treatment on endothelial dysfunction has been demonstrated and, empirically, in cooperation with the investigational site's pain unit, a symptomatic improvement in women with endometriosis and OSAHS after initiation of CPAP treatment was observed.

The study aims at exploring the occurrence of OSAHS in patients with endometriosis followed in the site's dedicated pain unit and the impact of OSAHS treatment when it exists, on the symptoms of endometriosis and quality of life.

OSAHS diagnosis will be made according to standard of care practice in the investigation site. Patients with confirmed diagnosis of OSAHS will be treated according to national recommendations for this disease (CPAP or alternative treatments) and will complete questionnaires at 3, 6 and 12 months after start of OSAHS treatment to assess the impact of OSAHS treatment on various endometriosis-related symptoms.

Inclusion Criteria:

• Female patients aged between 18 and 50 years of age
• Confirmed diagnostic of endometriosis (either through imaging procedure (ultrasound or RMI) or diagnostic coelioscopy)
• Patient suffering from symptoms evocating Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS) and justifying a diagnosis process performed within Standard of Care practice
• Patient who has been informed about the study and has signed the informed consent form prior to any study-specific procedures
• Patient willing and able to perform all scheduled procedures in accordance with the study protocol

Exclusion Criteria:

• Post menopausal patient
• Ongoing treatment for OSAHS
• Patient with Chronic Obstructive Pulmonary Disease (COPD) or unstabilized cardiac disorders
• Concomitant participation in another clinical trial
• Pregnant or breastfeeding woman
• Patient under legal protection measure

Patients with confirmed endometriosis, that are followed for pain at the site's dedicated pain unit, and who display OSAHS symptoms.