What is the recommended prophylaxis for patients at moderate to high risk of developing deep vein thrombosis (DVT), such as those hospitalized for surgery, trauma, or with acute medical conditions?

DVT Prophylaxis in Hospitalized Patients

For hospitalized medical and surgical patients at moderate to high risk of DVT, use pharmacologic prophylaxis with LMWH, low-dose unfractionated heparin (LDUH), or fondaparinux as first-line agents, combined with mechanical prophylaxis (intermittent pneumatic compression) when feasible. 1, 2

Risk Stratification

• High-risk medical patients requiring prophylaxis include acutely ill hospitalized patients with reduced mobility, active malignancy, history of prior VTE, age >60 years, obesity, or recent surgery/trauma 1, 2, 3
• High-risk surgical patients include those undergoing major abdominal/pelvic surgery, hip fracture surgery, cancer surgery, thoracic surgery, or patients with restricted mobility 1, 3
• Low-risk patients (ambulatory, no risk factors) should NOT receive pharmacologic prophylaxis due to bleeding risk without meaningful benefit 1, 2

Pharmacologic Prophylaxis: First-Line Agents

For acutely ill medical patients at increased thrombotic risk, the American College of Chest Physicians recommends anticoagulant thromboprophylaxis with LMWH, LDUH, or fondaparinux. 1, 2

Specific Dosing Regimens

• Enoxaparin (LMWH): 40 mg subcutaneously once daily 3
• Unfractionated heparin: 5000 units subcutaneously twice daily OR three times daily 1, 3
• Fondaparinux: 2.5 mg subcutaneously once daily 1, 3

Choosing Between Agents

• All three agents have equivalent efficacy, so selection should be based on once-daily versus multiple daily dosing convenience, renal function, and local formulary costs 3
• For renal impairment (CrCl <30 mL/min): Reduce enoxaparin to 30 mg once daily OR switch to unfractionated heparin 5000 units subcutaneously every 8 hours, as LMWH is contraindicated in severe renal impairment 3, 4
• For fondaparinux with CrCl 30-50 mL/min: Reduce dose to 1.5 mg once daily 3
• For obesity (>150 kg): Consider increasing enoxaparin to 40 mg subcutaneously every 12 hours 3

Duration of Prophylaxis

• Medical patients: Continue prophylaxis throughout hospitalization, but do NOT extend beyond the period of patient immobilization or acute hospital stay 1, 2, 3
• Surgical patients: Continue for 7-10 days postoperatively for most procedures 3
• Extended prophylaxis (4 weeks total) is strongly recommended for major abdominal/pelvic surgery, hip fracture surgery (up to 32 days), cancer surgery patients, and patients with restricted mobility, obesity, or history of VTE 3, 4
• Acutely ill medical patients: 31-39 days total duration (in hospital and after discharge) 1, 5

Surgical-Specific Recommendations

Thoracic Surgery

• Moderate-risk patients: LDUH, LMWH, or mechanical prophylaxis with intermittent pneumatic compression 1
• High-risk patients: LDUH or LMWH plus mechanical prophylaxis (elastic stockings or IPC) 1

Cardiac Surgery

• For prolonged hospital course with non-hemorrhagic complications, add pharmacologic prophylaxis (LDUH or LMWH) to mechanical prophylaxis 1

Neurosurgery (Craniotomy)

• Standard approach: Mechanical prophylaxis with IPC is preferred over pharmacologic prophylaxis due to bleeding risk 1
• Very high-risk patients (malignant disease): Add pharmacologic prophylaxis once adequate hemostasis is established and bleeding risk decreases 1

Spinal Surgery

• Standard approach: Mechanical prophylaxis with IPC is preferred over unfractionated heparin or LMWH 1
• High-risk patients (malignancy, combined anterior-posterior approach): Add pharmacologic prophylaxis once hemostasis is established 1

Major Trauma Patients

• Use LDUH, LMWH, or mechanical prophylaxis with IPC 1, 6
• High-risk trauma patients (spinal cord injury, traumatic brain injury, spinal surgery): Add mechanical prophylaxis to pharmacologic prophylaxis when not contraindicated by lower-extremity injury 1
• IVC filters should NOT be used for primary VTE prevention in trauma patients 1
• Routine surveillance ultrasound should NOT be performed 1

Hip or Knee Replacement Surgery

• Rivaroxaban 10 mg once daily with or without food is FDA-approved for this indication 5
• Start 6-10 hours after surgery once hemostasis is established 5
• Duration: 35 days for hip replacement, 12 days for knee replacement 5

Mechanical Prophylaxis

For patients at high risk for major bleeding or actively bleeding, use mechanical thromboprophylaxis with graduated compression stockings OR intermittent pneumatic compression instead of pharmacologic agents. 1, 2, 3

• When bleeding risk decreases, substitute pharmacologic prophylaxis for mechanical prophylaxis 1, 3
• Combined approach: For high-risk surgical patients not at high bleeding risk, combine pharmacologic and mechanical prophylaxis (IPC for 18 hours daily) to further reduce DVT risk 1, 4

Absolute Contraindications to Pharmacologic Prophylaxis

• Active bleeding 1, 3
• Severe thrombocytopenia (platelet count <50,000/μL) 3
• Active intracranial bleeding in CNS malignancy patients 3
• Recent neurosurgery 3
• Coagulopathy or hemodynamic instability 4

Special Populations

Cancer Patients

• Hospitalized cancer patients: Follow standard medical patient recommendations with LMWH, LDUH, or fondaparinux 1, 3
• Ambulatory cancer patients: Primary prophylaxis for locally advanced/metastatic pancreatic cancer receiving chemotherapy, patients with Khorana score ≥2 receiving systemic therapy, and myeloma patients on immunomodulatory drugs with steroids 3
• Do NOT use routine prophylaxis for lung cancer patients (outside clinical trials) or patients with indwelling central venous catheters 1, 3

Critically Ill Patients

• Use LMWH or LDUH thromboprophylaxis 1
• For high bleeding risk, use mechanical prophylaxis (graduated compression stockings or IPC) until bleeding risk decreases 1
• Do NOT perform routine ultrasound screening for DVT 1, 2

Chronically Immobilized Patients (Home/Nursing Home)

• Do NOT use routine thromboprophylaxis in chronically immobilized persons residing at home or nursing homes 1, 2

Long-Distance Travelers

• For travelers at increased risk (previous VTE, recent surgery/trauma, active malignancy, pregnancy, estrogen use, advanced age, limited mobility, severe obesity, known thrombophilic disorder): recommend frequent ambulation, calf muscle exercise, or sitting in an aisle seat 1, 2
• Use properly fitted below-knee graduated compression stockings providing 15-30 mm Hg pressure at the ankle during travel 2

Critical Warnings

Spinal/Epidural Hematoma Risk

• Epidural or spinal hematomas may occur with anticoagulation and neuraxial procedures, potentially causing permanent paralysis 3, 5
• Monitor patients frequently for signs and symptoms of neurological impairment and treat urgently if observed 5
• Consider benefits and risks before neuraxial intervention in anticoagulated patients 5

Premature Discontinuation

• Premature discontinuation of any oral anticoagulant increases the risk of thrombotic events 5
• Consider coverage with another anticoagulant if discontinued for reasons other than pathological bleeding or completion of therapy 5

Common Pitfalls to Avoid

• Do NOT overuse pharmacologic prophylaxis in low-risk patients, as this increases bleeding complications without meaningful benefit 2
• Do NOT use aspirin as sole thromboprophylaxis in surgical patients due to inferior efficacy compared to anticoagulants 4
• Do NOT use IVC filters for primary prevention in trauma patients 1
• Do NOT perform routine surveillance ultrasound in critically ill patients 1, 2
• Do NOT extend prophylaxis beyond hospital stay in medical patients without specific high-risk features 1, 2