What is venous thromboembolism? Venous thromboembolism, or VTE, refers to a clot that starts in a vein. Find our full video library only on Osmosis: http://osms.it/more. Join millions of current and future clinicians who learn by Osmosis, along with hundreds of universities around the world who partner with Osmosis from Elsevier to make medical and health education more engaging and efficient.