How long should anticoagulation be continued in a patient with bilateral lower‑extremity deep‑vein thrombosis and a recent negative pulmonary embolism workup?

Anticoagulation Duration for Bilateral Lower Extremity DVT

For bilateral lower extremity DVT, the patient requires a minimum of 3 months of therapeutic anticoagulation, with the decision to extend beyond 3 months determined by whether the DVT was provoked or unprovoked and the patient's bleeding risk. 1

Initial Treatment Phase (All Patients)

• All patients with acute DVT require at least 3 months of therapeutic anticoagulation to prevent thrombus extension and early recurrence, regardless of provoked or unprovoked status 1
• This 3-month minimum applies to both proximal and distal DVT 1
• The absence of pulmonary embolism does not change the anticoagulation duration recommendations for DVT 1

Decision Algorithm After 3 Months

If DVT Was Provoked by a Transient Risk Factor

• Stop anticoagulation at 3 months if the provoking factor was surgery or major trauma 1, 2
• Annual recurrence risk after stopping is <1% in this population 1
• For hormone-associated DVT in women, stop anticoagulation at 3 months if hormonal therapy is discontinued 3

If DVT Was Unprovoked (No Identifiable Risk Factor)

The decision depends on bleeding risk assessment:

Low or Moderate Bleeding Risk

• Extend anticoagulation indefinitely (no scheduled stop date) rather than stopping at 3 months 1
• Annual recurrence risk exceeds 5% after stopping anticoagulation, which substantially outweighs bleeding risk 3
• Low bleeding risk criteria include: age <70 years, no previous major bleeding episodes, no concomitant antiplatelet therapy, no severe renal or hepatic impairment, and good medication adherence 3

High Bleeding Risk

• Stop anticoagulation at 3 months 1
• High bleeding risk criteria include: age ≥80 years, previous major bleeding, recurrent falls, need for dual antiplatelet therapy, or severe renal or hepatic impairment 3

Special Populations

• Active cancer: Extend anticoagulation indefinitely regardless of bleeding risk (at least until resolution of malignancy), preferably with low molecular weight heparin 1
• Second unprovoked VTE: Strong recommendation for extended anticoagulation even with moderate bleeding risk 1

Ongoing Management for Extended Therapy

• Reassess bleeding risk, medication adherence, and patient preference at least annually 1, 3
• Consider reduced-dose DOACs (apixaban 2.5 mg twice daily or rivaroxaban 10 mg once daily) after completing 6 months of full-dose therapy to reduce bleeding risk while maintaining efficacy 3
• Target INR of 2.0-3.0 (target 2.5) if using warfarin for all treatment durations 1, 2

Critical Pitfalls to Avoid

• Do not use fixed time-limited periods beyond 3 months (such as 6 or 12 months) for unprovoked proximal DVT—guidelines recommend against this approach 1
• Do not assume bilateral DVT automatically requires longer treatment—the decision is based on provoked vs. unprovoked status, not the extent of thrombosis 1
• Do not stop anticoagulation prematurely before 3 months, as this increases early recurrence risk 3
• Do not fail to distinguish between proximal and distal DVT—isolated distal DVT has approximately half the recurrence risk and may not require extended therapy even when unprovoked 3