Ulipristal for Endometriosis-related Pelvic Pain

Inclusion Criteria: * Diagnosis of endometriosis with surgical confirmation via laparoscopy performed within 3 years prior to study enrollment * English-speaking reproductive-age women (18-50yo) with regular, cyclical menses * Treatment-refractory endometriosis, as defined by persistent or recurrent pelvic pain following one or more treatments involving surgery and/or hormonal treatment * Dysmenorrhea and chronic pelvic pain for a least one week out of the month during past 5 months or longer * Endometrial biopsy before and after intervention * Adequate organ and marrow function as defined below: * leukocytes ≥ 3,000/microliter * absolute neutrophil count ≥ 1,500/microliter * platelets ≥ 100,000/microliter * total bilirubin within normal institutional limits * Liver function tests ≤ 2.5 X institutional upper limit of normal * creatinine within normal institutional limits * Women of child-bearing potential must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry, for the duration of study participation, and for 90 days following completion of therapy. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately. * A female of child-bearing potential is any woman (regardless of sexual orientation, having undergone a tubal ligation, or remaining celibate by choice) who meets the following criteria: * Has not undergone a hysterectomy or bilateral oophorectomy; or * Has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months). * Ability to understand and the willingness to sign a written informed consent. Exclusion Criteria: * Undiagnosed vaginal bleeding * Abnormal results from endometrial biopsy * Presence of ovarian cysts ≥ 3 cm * Pregnancy * Refusal to adhere the birth control strategy of the study (use of a combination of a condom and a vaginal sponge during each intercourse while on ulipristal, plus one month before the onset and one month after the completion of ulipristal therapy) * Women taking digoxin, dabigatran or etexilate due to interference of ulipristal acetate with the concentration of these substances bound by plasma proteins. * Women taking moderate to potent inducers of hepatic metabolism (e.g. erythromycin, ketoconazole, ritonavir, nefazodone). * History of allergic reactions attributed to compounds of similar …