Determine the proportion of patients with endometriosis unresponsive to medical therapy and to compare the clinical and ultrasonographic characteristics of this group of patients (study group) with the clinical and ultrasonographic characteristics of patients responsive to medical therapy (control group).

Inclusion Criteria:

• age between 18 and 50 years;
• patients with endometriosis-related pain symptoms (dyspareunia, dyschezia, dysmenorrhea, chronic pelvic pain, dysuria, periovulatory pain, with at least one of these symptoms presenting Numerical Pain Rating Scale intensity > 5);
• indication for administration of oral hormonal medical treatment for endometriosis;
• acquisition of informed consent.

Exclusion Criteria:

• patients with contraindications to oral hormone treatment
• current or previous pelvic infections
• history of malignancy or current suspicion of gynecologic malignant lesions
• previous pelvic surgery (hysterectomy, salpingectomy, ovarian cyst removal, myomectomy, surgery for endometriosis, bowel resections)
• positive history of other causes of chronic pelvic pain
• post-menopausal status

Patients with clinical and ultrasound diagnosis of endometriosis with indication for administration of hormone therapy