Thrombophilias: when should we test and how does it help?

Venous thromboembolism can be a life-threatening event, occurring in ~1 in 1000 adults annually. An underlying cause for thrombosis can now be identified in up to 80% of cases, including both inherited and acquired causes of thrombophilia. In fact, it is often a combination of these risk factors that leads to the development of thrombosis. Knowing what these risk factors are for an individual patient can help with decisions regarding duration of anticoagulation, and how best to prevent a recurrent event. This article reviews both the inherited and the acquired causes of thrombophilia, focusing on the clinical scenarios in which these disorders should be suspected and on how to appropriately test for them when clinically indicated. By the conclusion of this article, the clinician should be equipped with an algorithm of how to approach a patient with a thromboembolic event, from decisions regarding which thrombophilia tests to order to how the results of these tests affect patient management.