Thrombus in pulmonary artery: Contrast computerized tomographic (CT) scan of thorax shows a filling defect in the right branch pulmonary artery. The density is like that of a thrombus. It could have originated from the deep veins of the lower limb as a pulmonary embolus or it could be an in situ thrombus formed in the pulmonary artery which is rarer. Pulmonary embolism is a potentially life threatening condition which needs prompt recognition and treatment. Such eminent eminent demonstration of pulmonary thrombus has made CT pulmonary angiography the gold standard in the diagnosis of pulmonary thromboembolism. If CT pulmonary angiogram is negative one can safely conclude that currently there is no pulmonary embolism, though rarely a recent embolus may have got fragmented and resolved.