When is the soonest that he can discontinue warfarin?

A 40-year-old male presents to his primary care physician for a routine health maintenance visit. Two months ago, the patient developed left thigh pain that was due to a deep venous thrombosis (DVT) in his left femoral vein following a total knee replacement. The patient has no history of venous thromboembolism (VTE) or malignancy. The patient was discharged on warfarin. The patient is currently asymptomatic, but irritated with the frequent blood draws to check his INR. His INR today is 2.7. Ultrasound imaging 1 week prior showed regression of the thrombus. When is the soonest that he can discontinue warfarin?

1.Immediaterly
2.In one month
3.In four months
4.In three years
5.Do not discontinue

exp:

In a patient with a provoked DVT associated with a transient risk factor (i.e., surgery), the minimum recommended anticoagulation duration is three months. Given that two months have passed, the soonest that anticoagulation can be discontinued is in one month.
The duration of warfarin therapy for DVT depends on the patient’s risk of developing a subsequent DVT. Reversible or transient risk factors include trauma, recent surgery, prolonged immobilization, and certain medication including OCPs. Nontransient factors include hypercoagulability disorders, malignancy, and past history of VTE. For a first DVT and for DVTs associated with transient risk factors, the recommended anticoagulation duration is specifically 3 months. If not, treatment period is considered “extended” (i.e. indefinite).

Illustration A shows a patient with a DVT of the left lower extremity. A unilateral erythematous and swollen leg with >3cm of asymmetry should raise concern for a DVT. Illustration B shows an ultrasound of the femoral vein with thrombus occluding the lumen.