Red Flags
- Active bleeding or recent intracranial haemorrhage — pharmacological prophylaxis contraindicated; use mechanical (intermittent pneumatic compression, GCS) until bleeding controlled[1]
- Heparin-induced thrombocytopenia (HIT) — stop heparin; alternative anticoagulation (argatroban, fondaparinux); haematology consult; do not start LMWH[1]
- Severe renal impairment (eGFR <30) — adjust LMWH dose, consider unfractionated heparin or graduated compression stockings; DOACs limited or avoided[1]
- Pregnancy with VTE risk factors — antenatal LMWH 6 weeks postpartum; assess at booking, after admission, and at 28 weeks[1]
First-line treatment
Interventions
- Universal risk and bleeding assessment[1]All hospitalised adults assessed within 24 h of admission and after major change in clinical status; document risk and prophylaxis prescribed; integrate into electronic admission bundle
- Pharmacological prophylaxis for moderate-high VTE risk[1]LMWH preferred over UFH; fondaparinux alternative; do NOT use DOAC for in-hospital prophylaxis (ASH 2018); duration: until ambulant or per pathway (orthopaedic 14–35 days, cancer surgery up to 4 weeks, medical typically until discharge)
- Mechanical prophylaxis when pharmacological contraindicated[1]Intermittent pneumatic compression preferred over graduated compression stockings; combine with pharmacological in highest-risk surgical (orthopaedic, cancer); discontinue when ambulant
- Outpatient VTE prevention[1]Long-distance travel >6–8 h: ambulation, hydration; GCS or LMWH only for high-risk individuals (prior VTE, active cancer, recent surgery, advanced pregnancy). Routine prophylaxis NOT recommended for long-term care, outpatients, or minor risk factors
- Intermittent pneumatic compression (IPC)[1]Preferred mechanical option over graduated compression stockings; sequential calf or thigh-length devices; compliance is critical — re-apply after toilet, mobilisation; combine with pharmacological in highest-risk
First-line drug therapy
| Drug | Class | Adult | Paediatric | Notes |
|---|---|---|---|---|
| Enoxaparin (LMWH)[1] | Low-molecular-weight heparin | 40 mg SC daily; 30 mg BD in some surgical regimens; 20 mg daily if eGFR <30 (or use UFH) | 0.5 mg/kg/dose BD | First-line pharmacological prophylaxis; weight-adjusted for BMI ≥40 (enoxaparin 0.5 mg/kg BD); HIT incidence ~1%; renal dose adjustment |
| Dalteparin (LMWH alternative)[1] | Low-molecular-weight heparin | 5000 units SC daily for prophylaxis | — | Alternative to enoxaparin; preferred for cancer-associated VTE (CLOT trial) |
| Unfractionated heparin (UFH)[1] | Unfractionated heparin | 5000 units SC every 8 or 12 h | — | Preferred when eGFR <30, dialysis, or rapid reversal needed; higher HIT risk than LMWH; no monitoring needed for prophylactic dose |
| Fondaparinux[1] | Synthetic factor Xa inhibitor | 2.5 mg SC daily | — | Alternative when LMWH contraindicated (HIT, religious dietary preferences avoiding porcine); no antidote available; renal dose adjustment |
| Apixaban or rivaroxaban (post-arthroplasty extended)[1] | DOAC (factor Xa inhibitor) | Apixaban 2.5 mg PO BD × 12 days (knee) or 35 days (hip); rivaroxaban 10 mg PO daily × 14 days (knee) or 35 days (hip) | — | Approved for post-orthopaedic prophylaxis; not for acute medical inpatient prophylaxis (ASH 2018); MAGELLAN suggested signal for medical prophylaxis but ASH does not endorse |
Enoxaparin (LMWH)[1]
Low-molecular-weight heparin
- Adult
- 40 mg SC daily; 30 mg BD in some surgical regimens; 20 mg daily if eGFR <30 (or use UFH)
- Paediatric
- 0.5 mg/kg/dose BD
First-line pharmacological prophylaxis; weight-adjusted for BMI ≥40 (enoxaparin 0.5 mg/kg BD); HIT incidence ~1%; renal dose adjustment
Dalteparin (LMWH alternative)[1]
Low-molecular-weight heparin
- Adult
- 5000 units SC daily for prophylaxis
- Paediatric
- —
Alternative to enoxaparin; preferred for cancer-associated VTE (CLOT trial)
Unfractionated heparin (UFH)[1]
Unfractionated heparin
- Adult
- 5000 units SC every 8 or 12 h
- Paediatric
- —
Preferred when eGFR <30, dialysis, or rapid reversal needed; higher HIT risk than LMWH; no monitoring needed for prophylactic dose
Fondaparinux[1]
Synthetic factor Xa inhibitor
- Adult
- 2.5 mg SC daily
- Paediatric
- —
Alternative when LMWH contraindicated (HIT, religious dietary preferences avoiding porcine); no antidote available; renal dose adjustment
Apixaban or rivaroxaban (post-arthroplasty extended)[1]
DOAC (factor Xa inhibitor)
- Adult
- Apixaban 2.5 mg PO BD × 12 days (knee) or 35 days (hip); rivaroxaban 10 mg PO daily × 14 days (knee) or 35 days (hip)
- Paediatric
- —
Approved for post-orthopaedic prophylaxis; not for acute medical inpatient prophylaxis (ASH 2018); MAGELLAN suggested signal for medical prophylaxis but ASH does not endorse
Safety-net
- Take prescribed prophylactic injections daily — most VTE happens after discharge in some surgical groups; complete the prescribed duration[1]
- Calf swelling, pain, sudden breathlessness, chest pain, or haemoptysis after recent admission or surgery — emergency department for VTE assessment[1]
- Resume normal activity and walking as early as possible after admission or surgery — early mobilisation reduces VTE risk most effectively[1]
Referral criteria
- Suspected DVT (calf swelling, pain) or PE (sudden breathlessness, chest pain, haemoptysis)Emergency department / acute medical assessment with D-dimer and imaging[1]
- HIT suspicion (platelet drop ≥50% or new thrombosis on heparin)Haematology and switch to alternative anticoagulant[1]
- Pregnancy with personal or family VTE history requiring antenatal prophylaxisJoint obstetric and haematology[1]
- Recurrent unprovoked VTE or significant anticoagulation contraindicationsHaematology / thrombosis specialist[1]
Clinical summary
VTE risk-based pharmacological and mechanical prophylaxis for hospitalised medical, surgical, and obstetric patients, and high-risk outpatients.