Table 1 Potential precipitating risk factors assessed regarding the past venous thromboembolic event Minor transient (i.e. now resolved) risk factors within 8 weeks of initial VTE
Minor transient (i.e. now resolved) risk factors within 8 weeks of initial VTE | Major transient (i.e. now resolved) risk factors within 8 weeks of initial VTE | Known hypercoagulable state |
|---|---|---|
Pregnancy | Leg casting | Deficiency of antithrombin, protein C, or protein S |
Postpartum (defined as 6 weeks after delivery) | Major surgery (>30 minutes; general or spinal anesthesia) | Activated protein C resistance/factor V Leiden |
Hormonal contraception (birth control pill, patch or needle) | Acute medical illness with hospital admission for ≥ 3 days | Prothrombin gene mutation |
Airplane travel (longer than 6 hours) | Immobilization ≥ 3 days (in bed except to go to washroom) | Anticardiolipin antibody positivity |
Active cancer | Nonspecific inhibitor |