This study will test the hypothesis that the molecular changes present in ectopic endometriosis lesions correlate with progesterone-resistant disease (using the criteria defined in this study) and are present in matched eutopic endometrium.

Tissues from 100 patients with endometriosis will be analyzed with droplet digital PCR (ddPCR) targeted sequencing and responders (n=50) will be compared to non-responders (n=50) after controlling confounding factors.

From a subset of the 100 cases, whole exome sequencing (WES) and Methylation-Specific PCR (MSP)-based methylation profiling on microdissected epithelium and stroma will be performed in matched eutopic and ectopic tissues from 20 patients with known cancer-associated mutations or 20 controls.

Inclusion Criteria:

• Signed informed consent.
• Gender: female.
• Age: 18-45 years at the time of signing consent.
• Clinical or surgical diagnosis of endometriosis undergoing laparoscopy.
• Controls may not have clinical or surgical diagnosis of endometriosis.
• Regular menstrual cycles.
• BMI between 18-40 kg/m2.
• Sexually active or have had a previous vaginal exam that used a speculum.
• English speaking

Exclusion Criteria:

• Use of any kind of steroidal therapy including oral contraceptives, Norplant, estrogen replacement/supplemental therapy, androgens (Danazol, Cyclomen, Danocrine, testosterone) or progesterone. She may not be taking or be on Celebrex.
• Pregnant.
• Presence of pelvic infection.
• Mullerian anomalies with absence of a cervix.
• History of cancer of the reproductive tract.
• Presence of undiagnosed uterine bleeding.
• Treatment with intrauterine device (IUD) or progestin-containing intrauterine device.

Women between the ages of 18-45 undergoing surgical management for endometriosis as cases and women between ages of 18-45 years undergoing elective tubal ligation and no diagnosis of endometriosis.