The most common cause of Pulmonary thromboembolism is

A late effect of DVT is a postphlebitic syndrome, which eventually occurs in more than one-half of DVT patients. Postphlebitic syndrome (also known as a post-thrombotic syndrome or chronic venous insufficiency) is a delayed complication of DVT that causes the venous valves of the leg to become incompetent and exude interstitial fluid. Patients complain of a chronic ankle or calf swelling and leg aching, especially after prolonged standing.Ref: Harrison's 18/e p2170, 17/e p1651