Endometriosis is an estrogen-dependent chronic inflammatory disease characterized by the presence of endometrial tissue outside the uterine cavity. This pathology has a prevalence of about 5-10% in reproductive-aged women. Endometriosis therapy uses two options: surgical or medical (hormonal) but none can be considered completely resolving. Related signs and symptoms include dysmenorrhea, dyspareunia, infertility, dysuria and dyschezia. In addition to typical gynecological symptoms, gastrointestinal symptoms (bloating, nausea, constipation, diarrhea and vomiting) affect up to 90% of patients with endometriosis. Despite its high prevalence and associated morbidity, its etiology is still unclear and is thought to be multifactorial, and genetic, hormonal, environmental and immunological factors contribute to it. Several studies have shown a significant association between abnormal immune response and maintenance of disease activity in women with endometriosis.

The microbiome contains all the genetic material of microbes, including bacteria, fungi, viruses and Archaea, which live inside the host and regulate various physiological functions. The set of these bacteria, fungi, viruses and Archaea is called a microbiota. The influence of the microbiome on immunomodulation and the development of various inflammatory diseases is well established. Conversely, little is known about the presence and composition of the microbiome in the female reproductive system and its role in the development of endometriosis or other gynecological conditions. Considering the altered inflammatory state typical of endometriosis, it seems logical to postulate a potential role of the microbiome in the etiopathogenesis of this pathology. Interestingly, the microbiome affects estrogen metabolism and estrogen affects the gut microbiome. Since endometriosis is an estrogen-dependent disease, a picture of intestinal dysbiosis resulting in abnormal circulating estrogen levels could potentially contribute to the development of this disease.

Inclusion Criteria:

• BMI <30 kg / m2
• no hormonal therapy (estrogen-progestin, progestogen, GnRH analogues) in progress for at least 1 month
• the endometriosis group include women who will undergo surgery for endometriosis. The control group include women who will undergo surgery for other gynecological indications (i.e .: abdominal surgical emergencies, tubal infertility, non-endometriotic ovarian cysts) in which the presence of endometriosis will be excluded during the surgery.

Exclusion Criteria:

• hormonal therapy in progress (estrogen-progestins, progestins, GnRH analogues)
• antibiotic and / or probiotic therapy in the 8 weeks before the samples
• pregnancy
• menopausal state
• BMI ≥ 30 kg / m2
• presence of active systemic diseases, neoplasms, positive clinical history for autoimmune diseases, active vaginosis or positive history for pelvic inflammatory disease