Management of Deep Vein Thrombosis (DVT)
For a patient with acute DVT, initiate anticoagulation immediately with low-molecular-weight heparin (LMWH) or fondaparinux, as LMWH is superior to unfractionated heparin for reducing mortality and major bleeding. 1
Initial Anticoagulation
First-Line Therapy
- Start LMWH or fondaparinux immediately upon diagnosis 1
- LMWH is preferred over unfractionated heparin (UFH) due to superior efficacy in reducing mortality and bleeding risk 1
- Specific LMWH dosing options: 1, 2
- Enoxaparin 1 mg/kg subcutaneously every 12 hours, OR
- Enoxaparin 1.5 mg/kg subcutaneously once daily, OR
- Dalteparin 200 IU/kg subcutaneously once daily (maximum 18,000 IU), OR
- Tinzaparin 175 anti-Xa IU/kg subcutaneously once daily
- Fondaparinux dosing (weight-based): 1, 3
- 5 mg for patients <50 kg
- 7.5 mg for patients 50-100 kg
- 10 mg for patients >100 kg
Transition to Oral Anticoagulation
- Start warfarin on the same day as parenteral therapy 1
- Continue LMWH/fondaparinux for minimum 5 days AND until INR ≥2.0 for at least 24 hours 1, 4, 5
- Target INR: 2.0-3.0 1, 4, 5
Inpatient vs. Outpatient Management
Outpatient treatment with LMWH is safe and cost-effective for carefully selected patients 1
Criteria for Outpatient Treatment 1, 6
- Hemodynamically stable
- No active bleeding or high bleeding risk
- No severe renal impairment (LMWH contraindication)
- Adequate home support services available
- No concomitant symptomatic pulmonary embolism (relative contraindication)
- Reliable patient who can adhere to therapy
Exclude from Outpatient Treatment 1
- Significant comorbid illnesses requiring hospitalization
- Previous heparin-induced thrombocytopenia
- Pregnancy (requires specialized management)
- Geographic inaccessibility for follow-up
Duration of Anticoagulation
Duration depends on the underlying cause and risk factors for recurrence: 1, 5
Provoked DVT (Transient Risk Factor)
Unprovoked (Idiopathic) DVT
- Minimum 6-12 months of anticoagulation 1, 5
- Consider indefinite anticoagulation with periodic risk-benefit reassessment 1, 5
- Extended therapy reduces recurrence risk by 64-95% 1
Recurrent DVT
- Minimum 12 months, strongly consider indefinite anticoagulation 1
Cancer-Associated DVT
- LMWH monotherapy (not warfarin) for at least 3-6 months or as long as cancer is active 1
- Specific regimens: 1
- Dalteparin 200 IU/kg daily for 1 month, then 150 IU/kg daily, OR
- Tinzaparin 175 anti-Xa IU/kg daily, OR
- Enoxaparin 1.5 mg/kg daily
Prevention of Post-Thrombotic Syndrome
- Begin graduated compression stockings (30-40 mmHg) within 1 month of diagnosis 1, 4
- Continue for minimum 1-2 years 1, 4
- This intervention markedly reduces incidence and severity of post-thrombotic syndrome 1
Special Populations
Pregnancy
- Avoid warfarin due to embryopathy risk (6-12 weeks gestation) and fetal bleeding 1
- Use LMWH or UFH throughout pregnancy (neither crosses placenta) 1
- Specific evidence for optimal regimens is insufficient 1
Heparin-Induced Thrombocytopenia
- Use direct thrombin inhibitors (argatroban or lepirudin) instead of heparin 1
Renal Impairment
- Prefer UFH over LMWH/fondaparinux, as LMWH is retained in renal failure 1
Common Pitfalls to Avoid
- Never delay anticoagulation while awaiting confirmatory testing if clinical suspicion is high 1
- Do not stop LMWH before INR is therapeutic (≥2.0 for 24 hours) 4
- Avoid discontinuing anticoagulation prematurely in unprovoked DVT 4
- Do not use warfarin as first-line therapy in cancer patients—use LMWH monotherapy 1
- Ensure minimum 5-day overlap of parenteral and oral anticoagulation regardless of INR 1, 4