What is the recommended prophylaxis for patients at risk of developing deep vein thrombosis (DVT)?

DVT Prophylaxis

For acutely ill hospitalized medical patients at increased risk of thrombosis, initiate pharmacologic prophylaxis immediately upon admission with LMWH (enoxaparin 40 mg subcutaneously once daily), low-dose unfractionated heparin (5000 units subcutaneously twice or three times daily), or fondaparinux (2.5 mg subcutaneously once daily) throughout hospitalization. 1, 2, 3

Risk Stratification Framework

Use validated risk assessment tools to identify patients requiring prophylaxis:

• Calculate the Padua Prediction Score for all hospitalized medical patients—a score ≥4 indicates high risk (11% VTE incidence without prophylaxis, reduced to 2.2% with prophylaxis) and mandates pharmacologic prophylaxis. 4
• Alternatively, use the IMPROVE VTE Risk Assessment Model where a score ≥2 indicates need for prophylaxis, and ≥4 indicates high risk (5.7% VTE rate). 4
• High-risk features requiring prophylaxis include: active cancer, previous VTE, reduced mobility >3 days, age >60-65 years, critical illness, known thrombophilia, recent surgery/trauma, severe obesity, or mechanical ventilation. 1, 2

Assess bleeding risk concurrently using the IMPROVE Bleeding Risk Assessment Model:

• Score <7 indicates low bleeding risk (0.4% major bleeding)—proceed with pharmacologic prophylaxis. 4
• Score ≥7 indicates high bleeding risk (4.1% major bleeding)—use mechanical prophylaxis only. 4

Pharmacologic Prophylaxis Options

First-line agents (equivalent efficacy—choose based on dosing convenience, renal function, and cost):

• Enoxaparin 40 mg subcutaneously once daily 2, 3
• Dalteparin 5000 IU subcutaneously once daily 2
• Unfractionated heparin 5000 units subcutaneously twice or three times daily 1, 2, 3
• Fondaparinux 2.5 mg subcutaneously once daily 1, 2, 3

LMWH is preferable over unfractionated heparin due to higher effectiveness in preventing DVT and once-daily dosing convenience. 2

Critical Dose Adjustments

Renal impairment:

• Fondaparinux: reduce to 1.5 mg once daily if creatinine clearance 30-50 mL/min 2, 3
• Enoxaparin: reduce to 30 mg once daily if creatinine clearance <30 mL/min 2, 3
• Unfractionated heparin requires no dose adjustment and is preferred in severe renal failure 2

Obesity:

• For patients >150 kg, increase enoxaparin to 40 mg subcutaneously every 12 hours 2, 3

Duration of Prophylaxis

Medical patients:

• Continue prophylaxis throughout hospitalization and the period of immobilization—do NOT extend beyond hospital discharge unless the patient remains immobile. 1, 2

Surgical patients:

• Standard duration: 7-10 days postoperatively for most surgical patients 2, 3
• Extended prophylaxis (up to 4 weeks total): mandatory for major abdominal/pelvic cancer surgery, hip fracture surgery, and patients with restricted mobility, obesity, or history of VTE 2, 3

Acutely ill medical patients at risk for thromboembolic complications:

• Rivaroxaban 10 mg once daily (with or without food) in hospital and after discharge for a total duration of 31-39 days is FDA-approved for this indication. 5

High Bleeding Risk Patients

Absolute contraindications to pharmacologic prophylaxis:

• Active bleeding or recent major bleeding within 3 months 2
• Severe thrombocytopenia (platelet count <50,000/μL) 3
• Active coagulopathy with INR >1.5 2
• Recent neurosurgery or active intracranial bleeding 3

For patients with high bleeding risk who still require VTE prophylaxis:

• Use mechanical prophylaxis with intermittent pneumatic compression devices (IPC) or graduated compression stockings (15-30 mm Hg at ankle) instead of pharmacologic agents. 1, 2
• When bleeding risk decreases, immediately substitute pharmacologic prophylaxis for mechanical methods. 1, 2

Special Populations

Cancer patients:

• All hospitalized cancer patients with major medical illness or reduced mobility should receive prophylactic anticoagulation unless contraindicated by bleeding risk—LMWH is the preferred agent. 2
• For ambulatory cancer patients: provide prophylaxis for those with locally advanced/metastatic pancreatic cancer receiving chemotherapy, Khorana score ≥2 receiving systemic therapy, or myeloma patients on immunomodulatory drugs with steroids. 3
• Do NOT use routine prophylaxis for cancer patients with indwelling central venous catheters. 1, 3

Trauma patients:

• LMWH is more effective than unfractionated heparin and should be initiated once bleeding risk is controlled. 2
• High-risk trauma patients (age >60-65, traumatic brain injury, chest injury with AIS >3, mechanical ventilation, major surgery, prior VTE) should combine mechanical and pharmacological prophylaxis. 2

Stroke patients:

• For ischemic stroke patients at high risk (unable to move lower limbs, unable to mobilize independently, previous VTE, dehydration, comorbidities like cancer): start LMWH or IPC devices immediately within 24 hours of admission if no contraindication exists. 2
• For intracerebral hemorrhage patients: delay pharmacologic prophylaxis for at least 48 hours after stroke onset and only after repeat brain imaging demonstrates hematoma stability. 2

Critically ill ICU patients:

• Use LMWH or low-dose unfractionated heparin thromboprophylaxis over no prophylaxis—10-30% of ICU patients develop DVT within the first week without prophylaxis. 1, 6

Critical Pitfalls to Avoid

• Do NOT provide prophylaxis to low-risk medical patients (Padua score 0-3)—this unnecessarily increases bleeding risk without benefit. 1, 4
• Do NOT use graduated compression stockings as primary prophylaxis in medical patients—they are ineffective and not recommended. 4
• Do NOT administer fondaparinux earlier than 6 hours post-surgery—this significantly increases major bleeding risk. 2
• Do NOT overlook renal function when dosing LMWH or fondaparinux—failure to adjust leads to over-anticoagulation and bleeding. 2, 3
• Do NOT forget extended prophylaxis (up to 4 weeks) after major cancer surgery or hip fracture surgery—this misses a critical window of elevated VTE risk. 2, 3
• NEVER use rivaroxaban or other direct oral anticoagulants in patients receiving neuraxial anesthesia or undergoing spinal puncture—epidural or spinal hematomas may occur, potentially causing permanent paralysis. 5
• Despite high-quality evidence, only 58.5% of at-risk surgical patients and 39.5% of at-risk medical patients receive appropriate VTE prophylaxis—actively implement risk assessment protocols to avoid this gap. 2