Testing for hypercoagulability generally begins after the development of a thrombotic event. Most of the time, thrombi are caused by the presence of more than one acquired risk factor. In these cases, performing blood tests to look for hereditary thrombophilias is not needed.  Clinical practice guidelines recommend screening for hypercoagulable states only in individuals with a high suspicion of an inherited clotting disorder. Factors that suggest this include a family history of thromboembolism, a personal history of thrombosis at a young age or in usual blood vessels, and a history of frequent miscarriages. Common lab tests for screening include looking at the levels of anticoagulant proteins in the blood, as well as genetic tests to identify the inherited mutation, such as factor V Leiden and G20210A mutation in the prothrombin gene.  In those who have experienced miscarriages along with thrombotic events, antiphospholipid syndrome should be suspected. In these cases, tests to look for an antiphospholipid antibody such as lupus anticoagulant should be performed.