What are the recommendations for preventing and treating thrombosis?

Thromboprophylaxis and Treatment of Venous Thromboembolism

Primary Prevention in Hospitalized Patients

For hospitalized medical patients without existing VTE, pharmacological thromboprophylaxis with low-molecular-weight heparin (LMWH) is recommended over mechanical prophylaxis or no prophylaxis. 1

• LMWH is preferred over unfractionated heparin (UFH) for thromboprophylaxis in hospitalized medical patients 1
• Pharmacological prophylaxis should be discontinued at hospital discharge rather than extended beyond discharge in most medical patients 1
• Mechanical prophylaxis alone should be reserved for patients at high bleeding risk 1

Special Populations Requiring Prophylaxis

Cancer patients at high risk for thrombosis receiving systemic therapy should receive parenteral thromboprophylaxis (LMWH), while those at intermediate risk do not require routine prophylaxis 1

• For cancer patients undergoing surgery at lower bleeding risk, use pharmacological over mechanical prophylaxis 1
• For cancer patients undergoing major abdominal/pelvic surgery, continue pharmacological thromboprophylaxis post-discharge 1
• Patients at high bleeding risk undergoing surgery should receive mechanical rather than pharmacological prophylaxis 1

Acute VTE Treatment

Initial Anticoagulation Choice

For patients with acute VTE and cancer, direct oral anticoagulants (DOACs) such as apixaban or rivaroxaban, or LMWH, are recommended for initial treatment. 1

• LMWH is strongly recommended over UFH for initial treatment of VTE in cancer patients 1
• In hemodynamically unstable patients or those with chronic kidney disease, unfractionated heparin is preferred due to its rapid reversibility and renal safety 2, 3
• For suspected high-risk pulmonary embolism, initiate IV unfractionated heparin immediately without waiting for diagnostic confirmation 2

Critical Contraindications

Never use DOACs in patients with antiphospholipid syndrome—this is an absolute contraindication. These patients require warfarin or heparin-based therapy 3

Duration of Anticoagulation

Provoked VTE (Surgery or Transient Risk Factor)

Treat for 3 months with anticoagulation, then discontinue. 1, 4

• For VTE provoked by surgery: 3 months of anticoagulation is recommended over shorter, longer, or extended therapy 1
• For VTE provoked by nonsurgical transient risk factors: 3 months is recommended, with extended therapy only if bleeding risk is low 1

Unprovoked VTE

For first unprovoked proximal DVT or PE with low-to-moderate bleeding risk, extended anticoagulation beyond 3 months is suggested. 1

• First unprovoked proximal DVT with low/moderate bleeding risk: extended anticoagulation is suggested over stopping at 3 months 1
• First unprovoked proximal DVT with high bleeding risk: stop at 3 months 1
• Second unprovoked VTE with low bleeding risk: indefinite anticoagulation is strongly recommended 1, 4
• Target INR for warfarin therapy is 2.0-3.0 for all VTE treatment 1, 4

Cancer-Associated VTE

For VTE in active cancer patients with low-to-moderate bleeding risk, extended anticoagulation is strongly recommended over stopping at 3 months. 1, 5

• DOACs (apixaban, edoxaban, or rivaroxaban) are suggested over LMWH for short-term treatment (3-6 months) in cancer patients 1
• Even with high bleeding risk, extended anticoagulation should be considered with close monitoring 5

Special Clinical Scenarios

Active or Recent GI Bleeding with Acute VTE

Place a temporary IVC filter while holding anticoagulation, then resume anticoagulation once hemostasis is achieved (typically 7-14 days). 5

• IVC filters are strongly recommended for acute PE with contraindication to anticoagulation 1, 5
• Once bleeding risk resolves, initiate conventional anticoagulant therapy 1, 5
• Remove retrievable IVC filters once anticoagulation can be safely resumed—failure to remove is a common pitfall 5

Antiphospholipid Syndrome with Recurrent Thrombosis

Initiate therapeutic UFH immediately, then transition to warfarin (target INR 2.0-3.0) for indefinite anticoagulation. 3

• UFH is preferred over LMWH in septic patients due to concerns about subcutaneous absorption 3
• Continue heparin bridging for minimum 5 days and until INR ≥2.0 for at least 24 hours 3
• Antiplatelet agents like clopidogrel have no role in VTE treatment and should be discontinued unless there is a separate indication 3

Common Pitfalls to Avoid

• Never delay anticoagulation while awaiting diagnostic confirmation in patients with high clinical suspicion and hemodynamic compromise 2
• Avoid LMWH or fondaparinux in chronic kidney disease with hemodynamic instability due to accumulation in renal dysfunction 2
• Do not use IVC filters routinely in addition to anticoagulants for acute DVT—they are only for contraindications to anticoagulation 1, 5
• Prolonged interruption of anticoagulation without temporary protective measures (IVC filter) in high-risk patients should be avoided 5
• Early ambulation is suggested over bed rest for acute DVT, though severe edema and pain may require temporary deferral 1