The hemostatic and inflammatory systems may activate each other. Endometriosis is a chronic inflammatory disease affecting 10% of women. The objective of this study is to compare the hemostatic effects of two treatments widely prescribed to women with endometriosis: the levonorgestrel intrauterine system (LNG-IUS) and the gonadotropin-releasing hormone analog (GnRHa) leuprolide acetate.

Hypothesis:

H0: There is no alteration in hemostatic system with the use of GnRHa or LNG-IUS H1: There is alteration in hemostatic system with the use of GnRHa or LNG-IUS

Materials and Methods: In this randomized open-label controlled trial, 44 women with endometriosis will be randomly allocated to one of two groups: 22 women will be assigned to use LNG-IUS and 22 to use GnRHa. The assessed variables will be D-dimers, fibrinogen, prothrombin time, activated partial thromboplastin time, coagulation factors (F) II, V, VII, VIII, IX, X, and XI, antithrombin (AT), protein C, free protein S, tissue plasminogen activator (t-PA), α2-antiplasmin, thrombin-antithrombin complex, and prothrombin fragment 1+2. All variables will be assessed before treatment and six months after treatment onset.

Inclusion Criteria:

• to have endometriosis
• aged 18 to 40 years
• Being without contraceptives for at least 3 months or with depot medroxyprogesterone acetate or GnRHa for at least 6 months at the time of randomization.

Exclusion Criteria:

• obese patients with a body mass index (BMI) ≥30 kg/m2
• smokers
• diabetics
• alcohol or drug users
• patients currently wishing to conceive
• patients with chronic diseases (except endometriosis)
• patients with infectious processes
• patients with a personal and/or family history of thromboembolic events
• patients taking medications known to interfere with inflammation markers (such as hormonal and nonhormonal anti-inflammatory agents) within the 15 days before the study.