Because there is still uncertainty about how to use D-dimer testing and a patient s sex to make decisions about extended therapy in patients with a rst unprovoked VTE, we have not made recommendations based on these factors. Revised Recommendations: These are unchanged from AT9 with one minor exception. A qualifying remark has been added to the recommendation that suggests extended therapy over stopping treatment at 3 months in patients with a rst unprovoked proximal DVT or PE and a low or moderate risk of bleeding; this remark notes that patient sex and D-dimer level measured a month after stopping anticoagulant therapy may in uence this treatment decision. If it becomes clear that, during the extended phase of treatment, there are important differences in the risk of recurrence or bleeding with the different anticoagulant agents, agent-speci c recommendations for extended therapy may become justi ed. 5. In patients with a proximal DVT of the leg or PE provoked by surgery, we recommend treatment with anticoagulation for 3 months over (i) treatment of a shorter period (Grade 1B), (ii) treatment of a longer, time-limited period (eg, 6, 12, or 24 months) (Grade 1B), or (iii) extended therapy (no scheduled stop date) (Grade 1B). 6. In patients with a proximal DVT of the leg or PE provoked by a nonsurgical transient risk factor, we recommend treatment with anticoagulation for 3 months over (i) treatment of a shorter period (Grade 1B) and (ii) treatment of a longer time-limited period (eg, 6, 12, or 24 months) (Grade 1B). We suggest treatment with anticoagulation for 3 months over extended therapy if there is a low or moderate bleeding risk (Grade 2B), and recommend treatment for 3 months over extended therapy if there is a high risk of bleeding (Grade 1B). 