Cerebral Venous Sinus Thrombosis Occurring During Estetrol/Drospirenone Combined Oral Contraceptive Use in a Woman With Multiple Thrombotic Risk Factors: A Case Report.

Estetrol/drospirenone (E4/DRSP) is a combined oral contraceptive noted for its minimal hemostatic impact compared to ethinyl estradiol-based preparations. However, real-world thrombotic risk data in patients with significant comorbidities remain limited. A woman in her early 40s with adenomyosis and menorrhagia was prescribed E4/DRSP. Six weeks later, she developed acute left upper extremity weakness; imaging confirmed superior sagittal sinus thrombosis. She had severe iron deficiency anemia (hemoglobin 6.4 g/dL). Multiple overlapping risk factors-including severe iron deficiency anemia with reactive thrombocytosis, adenomyosis, obesity, hypertension, and age over 40-likely contributed synergistically, and the independent contribution of E4/DRSP cannot be determined. She was treated with anticoagulation and transitioned to relugolix for adenomyosis management. Although E4/DRSP has a favorable coagulation profile, thrombotic risk persists in women with adenomyosis and severe anemia. Pre-prescription assessment including correction of anemia and consideration of estrogen-free alternatives is warranted.