Risk of venous thrombosis/thromboembolism
Ever since the market launch of the so-called "Pill" nearly 50 years ago, it has been known that all combined hormonal contraceptives increase the risk of thrombosis. Thrombosis is the medical term for the formation of a blood clot. It is a vascular disease (i.e. a disease of the blood vessels) in which a blood clot (thrombus) forms in a vein or artery and blocks it. A clotted structure made of blood forms inside the vessel. If left untreated, venous thromboses can, in rare cases, lead to thromboembolism. This is a potentially life-threatening situation in which blood vessels in the lungs become clogged.
A distinction is made between venous and arterial thrombosis, depending on the kind of blood vessel in which the blood clot forms. Arterial thrombosis is even rarer than venous thrombosis, however, and can cause strokes or an occlusion of the coronary vessels (heart attack).
