Table 3.

Summary of guidance statements

Question	Guidance statement
Secondary prevention following provoked VTE
Should thrombophilia testing be performed to help determine duration of anticoagulation following provoked VTE?	Do not perform thrombophilia testing following an episode of provoked VTE. Remark A positive thrombophilia evaluation is not a sufficient basis to offer extended anticoagulation following an episode of provoked VTE.
Secondary prevention following unprovoked VTE
Should thrombophilia testing be performed to help determine duration of anticoagulation following unprovoked VTE?	Do not perform thrombophilia testing in patients following an episode of unprovoked VTE. Limits/exceptions If a patient with unprovoked VTE and low bleeding risk is planning to stop anticoagulation, test for thrombophilia (Table 2) if test results would change this decision. Remark A negative thrombophilia evaluation is not a sufficient basis to stop anticoagulants following an episode of unprovoked VTE in a patient with low bleeding risk and willingness to continue therapy. Remark Heterozygosity for FVL or PGM does not increase the predicted risk of recurrence after unprovoked VTE to a clinically significant degree. See Chapter 3, “Guidance for the treatment of DVT and PE” for guidance on determining duration of anticoagulant therapy following unprovoked VTE.
Primary prevention in relatives of VTE patients
Should family members of patients with VTE or hereditary thrombophilia undergo thrombophilia testing?	Do not test for thrombophilia in asymptomatic family members of patients with VTE or hereditary thrombophilia. Remark As a family history of VTE confers an excess risk of thrombosis, relatives should be counseled regarding use of prophylaxis in high risk situations.
Primary prevention in female relatives of VTE patients considering estrogen
Should female relatives of patients with VTE or hereditary thrombophilia who are considering using estrogen-containing medications be tested for thrombophilia?	Do not test for thrombophilia in asymptomatic family members of patients with VTE or hereditary thrombophilia who are contemplating use of estrogen. Limits/exceptions If a woman contemplating estrogen use has a first-degree relative with VTE and a known hereditary thrombophilia (Table 2), test for that thrombophilia if the result would change the decision to use estrogen. Remark Family history of VTE in a first degree relative predicts an excess risk of thrombosis with estrogen use, even when thrombophilia testing is negative.
Primary prevention in female relatives of VTE patients who are contemplating pregnancy
Should female relatives of patients with VTE or hereditary thrombophilia who are contemplating pregnancy be tested for thrombophilia?	Do not test for thrombophilia in asymptomatic family members of patients with VTE or hereditary thrombophilia who are contemplating pregnancy. Limits/exceptions If a woman contemplating pregnancy has a first-degree relative with VTE and a known hereditary thrombophilia (Table 2), test for that thrombophilia if the result would change VTE prophylaxis decisions. Remark Women with a personal history of unprovoked, estrogen-associated or pregnancy associated VTE already carry an indication for prophylaxis, and are unlikely to benefit from thrombophilia testing. Remark Women with multiple family members affected by VTE are more likely to carry a higher risk thrombophilia such as AT deficiency which may impact prophylaxis decisions. See Chapter 6, “Guidance for the treatment of obstetric-associated VTE” for regimens recommended for prophylaxis based on history and thrombophilia status.
Timing of thrombophilia assessment
When thrombophilia testing is performed, at what point in the patient’s care should this be done?	Do not perform thrombophilia testing at the time of VTE diagnosis or during the initial 3-month course of anticoagulant therapy. When testing for thrombophilias following VTE, use either a 2-stage testing approach (see text) or perform testing after a minimum of 3 months of anticoagulant therapy has been completed, and anticoagulants have been held. Remark Pregnancy, sex and estrogen use reduce the levels of Protein S. Use of sex specific reference intervals, and testing prior to pregnancy or while not receiving estrogen preparations is preferred.