Medical Inpatient Thromboprophylaxis

Acutely ill medical inpatients with reduced mobility and a high clot risk benefit from drug prophylaxis, and the benefit is largest in the first 14 days. Prophylaxis is given when the risk of clotting is higher than the risk of bleeding, using a risk score and a bleeding checklist.

Who needs it. Reduced mobility of 3 days or more, and one or more of: active cancer, previous venous thromboembolism, age over 70 years, heart or respiratory failure, acute infection or inflammatory disease, obesity with body mass index over 30, hormonal therapy, known thrombophilia, or a recent stroke with leg weakness.

Who is not offered it. Patients who are fully mobile, those on therapeutic anticoagulation, and those with a bleeding contraindication.

• First choice: enoxaparin 40 mg subcutaneously once daily. Use 20 mg daily for creatinine clearance 15 to 30 mL/min or weight under 50 kg.
• Alternative: unfractionated heparin 5000 units subcutaneously every 8 to 12 hours, especially if creatinine clearance is under 30 mL/min.
• Fondaparinux 2.5 mg subcutaneously once daily if there is a history of heparin-induced thrombocytopenia.
• Oral prophylaxis: rivaroxaban 10 mg once daily or apixaban 2.5 mg twice daily have been used for extended prophylaxis after discharge in selected high-risk patients, but routine use is not advised because of bleeding.

Contraindications. Active major bleeding, platelets under 50 x 10^9/L, recent intracranial or spinal haemorrhage, severe uncontrolled hypertension, and untreated inherited bleeding disorder.

Mechanical. Intermittent pneumatic compression devices when drugs are contraindicated, until the contraindication ends.

Obesity. Body mass index 40 or over: enoxaparin 40 mg twice daily. Weight over 150 kg: consider anti-Xa monitoring.

Kidney impairment. Reduce enoxaparin to 20 mg once daily at creatinine clearance 15 to 30 mL/min, and change to unfractionated heparin under 15 mL/min.

Stroke. Ischaemic stroke with immobility: start prophylaxis after the first 24 to 48 hours once bleeding is excluded and thrombolysis effects have passed. Intracerebral haemorrhage: mechanical prophylaxis first, then low molecular weight heparin after 48 hours if the haematoma is stable.

Cancer and sepsis. The risk is high. Prophylaxis is given unless platelets are under 50 x 10^9/L.

Special groups. COVID-19 and other severe infections increase risk. In East Africa, malnourished patients and those with advanced HIV disease have higher clot rates, and bed rest in tuberculosis wards is a common trigger.

Monitoring. Reassess risk every 24 to 48 hours. Check full blood count at baseline and every 2 to 3 days for the first 14 days, and creatinine weekly.

Referral and escalation. Escalate for bleeding, a platelet fall over 50%, new leg swelling or chest symptoms, which need objective testing.

Stopping. Stop when the patient is mobile or at discharge, or after 14 days for most; extended prophylaxis is not routine.