The Impact of a Novel GnRH Antagonist With Add-back Therapy for Treatment of Uterine Fibroids and Endometriosis on Hemostasis Parameters

Uterine fibroids and endometriosis are two frequent diseases among women of reproductive age. They can be responsible for chronic and/or menstrual pelvic pain and abnormal uterine bleeding. The first-line management of these conditions relies on medical treatment. Hormonal treatment with contraceptive pill can be effective, although up to 30% of patients do not respond to this line of treatment. In this context, GnRH antagonists have been introduced. By suppressing ovulation, they inhibit the action of the gonadal axis and thus can reduce bleeding and pain associated with uterine fibroids and endometriosis. More recently, the GnRH antagonist known as Relugolix has been associated with a low-dose oestradiol and progesteron-line molecule, a medication known as Ryeqo. The goal of this type of treatment is to suppress ovulation while also minimizing symptôms which may derive from lack of oestrogen and progesterone in reproductive age women. While Ryeqo's efficacy has been proven by multiple large randomized controlled trials, its impact on blood coagulation has yet to be determined. Venous thromboembolism (VTE) is the main, potentially fatal, dleterious effect of oestrogen-containing hormonal treatmen, such as combined oral contraceptives (COC). Several epidemiological studies have found a 3-6 increase in the risk of VTE among women on COC. The thrombogenic risk can be assessed by measuring specific blood biomarkers, which are known to be correlated to the thrombogenic phenotype and allow an overview of the VTE risk prior to conducting large population-scale studies directly measuring the adverse event's prevalence. The aim of this study is to document the effects of Ryeqo® on hemostasis parameters in order to estimate the risk of VTE associated with its employ. An improved understanding of the VTE risk associated with Ryeqo® will allow to adapt hormonal treatment based on each woman's personal risk profile. The study will be explained to all women whose medical condition allows the prescription of Ryeqo. All women who give their consent to participate in the study will have a urinary pregnancy test and a blood sample drawn before beginning treatment with Ryeqo. A second visit will be scheduled at 3 months, throughout which a second blood sample will be drawn. A questionnaire including socio-demographic data and clinical symptoms will be completed both on the first and the second visit.