What investigations should be performed following a first pulmonary embolus?

Thromboembolic venous disease is both common and potentially serious, thus the first episode of pulmonary embolus calls for careful assessment. This i nvolves two stages: a search for a venous localization of the pulmonary emb olus and a search for risk factors contributing to thromboembolic venous di sease. The emergence of non-invasive echographic-Doppler techniques and ech ocardiography make possible the localization of any residual venous thrombu s. The risk of post thrombotic disease is raised in symptomatic thrombotic venous disease which requires wearing elastic stockings for a least two yea rs. On the other hand this risk has not been assessed in asymptomatic cases of venous thrombosis. A search for risk factors requires a detailed histor y, a rigorous clinical examination and a routine list of laboratory investi gations. Some complex investigations for detecting the early stages of a ne oplasm would not appear justified unless there is objective evidence to sup port his. At the same time thrombophilia studies are not currently performe d routinely for a first episode but may be suggested in the following cases : family history of thromboembolic venous disease, age less than 45, includ ing those in whom the episode occurs at the same time as pregnancy, or whil st taking hormone therapy, idiopathic thromboembolism, the association of a rterial and venous thrombi and finally venous thromboses occurring in an un usual anatomical site. Prospective studies have shown the value of long ter m anticoagulation in patients suffering from constitutional hemostatic anom alies. Finally, if there is an after thought of occult cancer or constituti onal thrombocytopenia a careful follow up should be performed particularly during the first year.