<prompt> The commonest cause of pulmonary embolism isThrombosis of prostatic veinsThrombosis of leg veinsInferior vena cava thrombosisNone of the above  <response>: Thrombi in a deep vein of the leg accounts for more than 95 of cases of pulmonary embolism. The most common source of emboli is DVT of femoropopliteal and iliac veins. But remember that : Most common site of DVT is calf veins Calf veins thrombosis are itself associated with a low risk for embolism, but when the thrombosis progresses proximally to involve the larger veins above knee, then the risk becomes very high. Ref : Love Bailey 24e p866 