Patients commonly develops pulmonary thromboembolism due to which of the following?

Pulmonary embolism generally results from dislodged thrombi originating in the leg veins or pelvis. More than 50% of such thrombi arise in the deep veins of the legs. Other less common sources of thrombi are the pelvic veins, renal veins, hepatic vein, right side of the hea, and upper extremities. Causes of dislodged thrombi in legs or pelvis include long-term immobility, chronic pulmonary disease, hea failure or atrial fibrillation, thrombophlebitis, autoimmune hemolytic anemia, recent surgery, hormonal contraceptives. Ref: Kochar's Clinical Medicine for Students By Dario M. Torre, Geoffrey C. Lamb, Jerome J. Van Ruiswyk, M.D., 2008, Page 55 ; Harrison 17th ed chapter 265