What is thromboprophylaxis (preventive measures against thromboembolic events) in patients at high risk, such as those undergoing major surgery, with a history of deep vein thrombosis (DVT) or pulmonary embolism (PE), cancer, or impaired mobility?

What is Thromboprophylaxis?

Thromboprophylaxis is the use of pharmacological agents (anticoagulants) and/or mechanical devices to prevent venous thromboembolism (VTE)—specifically deep vein thrombosis (DVT) and pulmonary embolism (PE)—in patients at increased risk, including those undergoing major surgery, with cancer, impaired mobility, or prior VTE history. 1

Core Concept

Thromboprophylaxis aims to prevent fatal pulmonary embolism as the primary objective and reduce morbidity from DVT and post-phlebitic syndrome as the secondary objective 2. VTE remains the most common preventable cause of death in hospitalized patients, with pharmacological prophylaxis reducing PE risk by 75% in surgical patients and 57% in medical patients 3.

Pharmacological Methods

The primary pharmacological agents include 1:

• Low-molecular-weight heparin (LMWH): Preferred agent with once-daily dosing (e.g., enoxaparin 40 mg subcutaneously daily) 1, 4
• Low-dose unfractionated heparin (LDUH): Given as 5,000 units twice or three times daily subcutaneously 1
• Fondaparinux: Factor Xa inhibitor alternative 1
• Warfarin: Vitamin K antagonist, less commonly used for prophylaxis 1

LMWH is generally preferred over unfractionated heparin due to higher efficacy, lower bleeding risk, and convenient once-daily administration 5, 2.

Mechanical Methods

Mechanical prophylaxis counteracts venous stasis and includes 1:

• Graduated compression stockings (GCS): Reduce DVT but have not been proven to prevent fatal PE 2
• Intermittent pneumatic compression (IPC): Reduces DVT rates by 39% as monotherapy 6
• Venous foot pumps: Alternative mechanical option 7

Mechanical methods should never be used as sole prophylaxis when pharmacological methods are safe to use, but serve as alternatives when bleeding risk is high or as adjuncts in very high-risk patients 1, 6.

Risk Stratification Determines Approach

High-Risk Patients Requiring Pharmacological Prophylaxis 1:

• Patients over 40 years undergoing major surgery (>30 minutes under general anesthesia) 2
• Cancer patients undergoing surgery 1
• Hip or knee replacement surgery 4
• Acutely ill hospitalized medical patients with restricted mobility 1
• History of prior VTE 2
• Multiple trauma with prolonged immobilization 7

Low-Risk Patients—No Prophylaxis Needed 1:

• Acutely ill hospitalized medical patients at low thrombosis risk should receive neither pharmacological nor mechanical prophylaxis (Grade 1B recommendation) 1

High Bleeding Risk—Mechanical Prophylaxis Only 1, 6:

• Active bleeding or very recent bleeding episodes 6
• Patients should receive GCS or IPC until bleeding risk decreases 1
• Pharmacological prophylaxis is absolutely contraindicated with active bleeding 6

Timing and Duration

Optimal initiation: 2 hours preoperatively for surgical patients, continuing until full mobility is restored 2, 1. For surgical patients, prophylaxis should continue for at least 7-10 days, with extended prophylaxis up to 4 weeks for high-risk abdominal/pelvic cancer surgery 1.

Medical patients: Prophylaxis should not extend beyond the period of immobilization or acute hospital stay 1. Continuation beyond discharge is generally not recommended except for ambulatory cancer patients on systemic therapy at high VTE risk 1.

Special Populations

Cancer Patients 1:

• Surgical: Pharmacological prophylaxis preferred unless high bleeding risk; combination mechanical plus pharmacological for highest-risk patients 1
• Medical inpatients: Standard prophylaxis during hospitalization, discontinue at discharge unless ambulatory on chemotherapy 1
• Outpatients: Routine prophylaxis not recommended except for multiple myeloma patients on thalidomide/lenalidomide regimens (use aspirin or LMWH) 1

Renal Impairment 4:

• Creatinine clearance <30 mL/min: Reduce enoxaparin dose or use unfractionated heparin with monitoring 4
• Severe renal impairment increases LMWH exposure by 65% 4

Post-Thrombolysis Stroke 5:

• Resume pharmacological prophylaxis within 24 hours after bleeding control is confirmed 5
• Use mechanical prophylaxis as bridge until safe to start pharmacological agents 5

Critical Contraindications

Absolute contraindications to pharmacological prophylaxis 6:

• Active bleeding
• Severe thrombocytopenia (platelets <50×10⁹/L) 5
• Unstable or expanding intracranial hemorrhage 5
• Uncontrolled severe hypertension (>230/120 mmHg) 5

Common Pitfalls

Do not use enoxaparin interchangeably with other heparins unit-for-unit—they differ in molecular weight, activity, and dosing 4. Monitor platelet counts; discontinue if platelets fall below 100,000/mm³ due to heparin-induced thrombocytopenia risk 4. Never use enoxaparin for thromboprophylaxis in pregnant women with mechanical heart valves—valve thrombosis has resulted in maternal and fetal deaths 4.