Thromboprophylaxis for Trauma and Orthopaedics Admissions

Assessment of VTE and bleeding risk

All patients must have their risk of venous thromboembolism (VTE) assessed at admission using the trauma and orthopaedics VTE prophylaxis risk assessment proforma (link only active if accessing via NHS network) and then every 72 hours.

Different specialty specific algorithms apply for medical, surgical and obstetrics (refer to AthenA).

Further information on assessment:

For every patient, consider mechanical prophylaxis.
Do not offer pharmacological prophylaxis to patients with risk factors for bleeding shown in table 2 below.

Table 1 – Indicators of patients at increased risk of VTE (thrombosis risk factors)

Regard patient as being at increased risk of VTE if they have one or more of the following risk factors:

Age >60 years of age
Dehydration
Obesity (BMI >30kg/m²)
Any significant medical illness (e.g. heart, metabolic, endocrine, or respiratory disease; acute infection; inflammatory condition)
Use of hormone replacement therapy (HRT)
Use of oestrogen-containing contraceptive
Active cancer or cancer treatment
Known thrombophilia
Pregnancy or <6 weeks post-partum
Varicose veins with phlebitis
Personal history or 1st degree relative with a history of VTE
Significantly reduced mobility for 3 days or more
Surgery with significant reduction in mobility
Critical care admission (e.g. HDU, ICU)
Hip or knee replacement
Hip fracture
Total anaesthetic + surgical time >90 minutes
Surgery involving pelvis or lower limb with a total anaesthetic + surgical time >60 minutes
Acute surgical admission with inflammatory or intra-abdominal condition
Achilles tendon rupture
Ankle fracture with splint/cast + non-weight bearing
Lower limb injury with splint/cast + non-weight bearing

N.B. Consider any admissions or illnesses since pre-operative assessment.

Table 2 – Indicators of patients at high risk of bleeding and contraindication to pharmacological VTE prophylaxis

Regard patient at risk of bleeding, and a contraindication to pharmacological VTE prophylaxis, if they have any of the following risk factors:

Active bleeding
Recent stroke (within 3 months)
Acute gastro-duodenal ulcer
Acute bacterial endocarditis - discuss with cardiologist
Known hypersensitivity (including heparin induced thrombocytopenia, HIT)
Thrombocytopenia (platelets <75 x 10⁹/L)
Concurrent use of oral anticoagulant - see below for further guidance
Concurrent use of oral dual anti-platelets - see below for further guidance
Concurrent use of therapeutic heparin
Untreated inherited bleeding disorders (e.g. haemophilia, von Willebrand disease)
Acquired bleeding disorders, e.g. acute liver failure
Uncontrolled hypertension (BP ≥230/120mmHg)
Epidural / spinal anaesthesia or lumbar puncture in previous 4 hours or expected within next 12 hours
Any other procedure with high bleeding risk
Neurosurgery, spinal or eye surgery

N.B. Patients with an Acute Coronary Syndrome or suspected DVT/PE should receive fondaparinux or treatment dose LMWH as appropriate following local clinical guidelines.

General management and treatment options

Emergency Admissions/Trauma	Pelvic Fractures - Enoxaparin SC 40mg^† once daily from admission and for 28 days post-op. Withhold 12 hours prior to surgery, and restarted 12 hours post-op. Hip Fractures - Enoxaparin SC 40mg^† once daily from admission and for 28 days post-op. Withhold 12 hours prior to surgery, and restarted 12 hours post-op. Spinal Injury Patients - Treated as per Local Spinal Injuries Policy. Immobile for ≥48 hours - Enoxaparin SC 40mg once daily during the period of immobilisation (not for more than 42 days). Ankle immobilisation - Enoxaparin SC 40mg once daily during the period of immobilisation (not for more than 42 days).
Elective Total Hip Replacement	First line: Enoxaparin SC 40mg^† 12 hours post-op then once daily for 28 days. Second Line: Enoxaparin SC 40mg^† 12 hours post-op then once daily for 10 days and then Aspirin oral 150mg once daily for a further 28 days.
Elective Total Knee Replacement	First Line: Enoxaparin SC 40mg^† 12 hours post-op then once daily for 14 days. Second line: Aspirin oral 150mg once daily for 14 days post-op.
Other Elective Orthopaedic Surgery	Enoxaparin SC 40mg^† once daily should be considered for all patients over 16 years who will be immobile for ≥48 hours or who will be in lower limb immobilisation post-op. Enoxaparin should be continued until mobile or lower limb immobilisation removed.
Outpatients and Day Surgery patients treated for lower limb injuries that require them to be non-weight bearing	First Line: Rivaroxaban oral 10mg once daily (off-label) for period of immobility (maximum 35 days). N.B. if eGFR 15-29ml/min – use with caution; if eGFR <15ml/min – avoid. Second Line: Enoxaparin SC 40mg once daily for period of immobility (maximum 35 days).
^†Adjust enoxaparin dose for weight (<50kg; >100kg) and renal impairment (creatinine clearance (CrCl) <30ml/min) - see here.

Prophylactic enoxaparin dosing adjustments

Enoxaparin dose is dependent on weight and renal function. Refer to guidance on enoxaparin dose adjustment below in patients with:

weight <50kg or >100kg
creatinine clearance (CrCl) <30ml/minute.

Patients on long term anti-platelets prior to surgery

Patients on any antiplatelet medication, including aspirin, clopidogrel, ticagrelor or prasugrel have an increased risk of bleeding.

However, it is considered that thromboprophylaxis with low molecular weight heparin (LMWH) post orthopaedic surgery in a patient on a single long term antiplatelet agent is acceptable in most cases.

If a patient is on dual antiplatelet therapy (DAPT), the risk of thrombus vs risk of bleeding must be discussed with the specialist who recommended the antiplatelet treatment. This discussion should take place at pre-assessment where possible or as early as possible following surgery. A treatment plan must be recorded in the patient’s notes.

Patients on oral anticoagulants prior to surgery

Patients on oral anticoagulant therapy, including warfarin, phenindione, rivaroxaban, apixaban, edoxaban or dabigatran, should have these stopped prior to any elective procedure and may require bridging. This should be decided at pre-operative assessment and should be documented in the patient’s notes. Oral anticoagulants can usually be restarted as soon as clinically appropriate post procedure.

Patients on warfarin may require LMWH in combination with warfarin until therapeutic INR has been achieved. See Perioperative Anticoagulant Guideline (link only active if accessing via NHS network) for additional information, including the management of non-elective patients.

Precautions with epidural / spinal anaesthesia and lumbar puncture

Do not give LMWH if epidural / spinal anaesthesia or lumbar puncture in previous 4 hours or expected within 12 hours.

Mechanical prophylaxis

Consider mechanical prophylaxis for all patients particularly if they have contraindications to LMWH, or if LMWH not required and early mobilisation is possible.

Apply on admission and continue until there is a return to the pre-morbid level of mobility.

Note, Intermittent Pneumatic Compression (IPC) devices (Flowtron^®) or foot impulse devices should be applied peri-operatively.

Advice on how to apply correctly and duration of wear should be given to the patient.

Contraindications to mechanical prophylaxis
Pulmonary oedema	Pressure sore
Peripheral arterial / vascular disease	Peripheral neuropathy
Cellulitis	Local leg conditions, e.g. dermatitis
Leg oedema	Extreme deformity
Leg / foot ulceration	Acute stroke

General recommendations

Facilitate early mobilisation as soon as possible.
Ensure adequate hydration.
Reassess VTE risk and bleeding risk every 72 hours, or sooner if patient's condition changes. Review treatment plan where appropriate, and document any changes in notes.
Do not offer VTE prophylaxis to patients on full anticoagulant therapy.
Patients on established anti-platelet therapy:
- Assess risks and benefits of stopping
- Do not regard anti-platelet therapy as adequate VTE prophylaxis.

Guideline reviewed	February 2026
Page updated	April 2026