Venous thromboembolism: the condition

Venous thromboembolic disease: a thrombus obstructing blood flow

Venous thromboembolism (VTE) encompasses venous thrombosis (VT) and its immediate complication, pulmonary embolism (PE). Venous thrombosis results from localized activation of the coagulation system, leading to the formation of a thrombus within the venous system. The thrombus can cause partial or total occlusion, thereby obstructing blood flow. Venous thrombosis can affect any part of the venous system, but the most common manifestations occur at sites of low blood flow in the deep venous network of the lower extremities.
Once formed, the thrombus can detach or fragment, migrate through the bloodstream—particularly into the pulmonary arteries—and cause a pulmonary embolism (PE), an acute and potentially fatal complication of thrombosis. Secondary venous insufficiency, or post-thrombotic syndrome, is a secondary and later complication of DVT.

Venous thromboembolic disease is a multifactorial condition, and various acquired, genetic, or environmental risk factors may be involved in its development. Among the main ones are age, cancer, surgery, immobilization, coagulation disorders, obesity, and pregnancy.
It is established that treatment with estrogen-progestin hormones (birth control pills) exposes women to an increased risk of venous thrombosis, especially during the first year of use.