All patients must have their risk of venous thromboembolism (VTE) assessed at admission (+/- at pre-admission clinic) using the appropriate risk assessment tool and then regularly during their stay in hospital. A record of these assessments must be made (e.g. on the specialty-appropriate Risk Assessment sheet) and documented in the thromboprophylaxis section of the kardex.
Assess the patient within 24 hours of admission using the following flowchart and indicators as guidance and reassess risk of bleeding and VTE within 48-72 hours of admission and regularly thereafter.
Different specialty specific algorithms apply for orthopaedics, ENT and obstetrics.
Further information on assessment:
Regard medical patients and surgical patients who have not had a surgical procedure as being at increased risk of VTE if they are expected to have ongoing (≥2 days) reduced mobility relative to their normal state and have one or more of the risk factors below. Regard post-operative patients as being at increased risk of VTE if they have one or more of the following risk factors:
This list is not comprehensive and there will be patients with other specific conditions which are sufficiently pro-thrombotic that merit thromboprophylaxis.
Regard patient at risk of bleeding if they have any of the following risk factors:
If creatinine clearance (CrCl) <30ml/minute, see below, under Renal Impairment, for guidance.
Enoxaparin should only be prescribed after assessing the risks of VTE and balancing against the risks of bleeding. Contraindications should be considered carefully (e.g. Heparin-induced Thrombocytopenia (HIT), acute bacterial endocarditis, renal impairment, recent stroke, etc).
Significant renal impairment (CrCl <30ml/minute) is associated with an increased anticoagulant-related bleeding risk. In some patients the bleeding risk associated with low molecular weight heparin (LMWH) may outweigh the anti-thrombotic benefit, when it would be appropriate to withhold enoxaparin and apply mechanical thromboprophylaxis. If enoxaparin is deemed appropriate then see here for dose reduction.
In low weight patients (<50kg) reduce the dose to enoxaparin SC 20mg daily. Extremely heavy patients (>120kg), with normal renal function, may merit a higher dose; enoxaparin 40mg SC twice daily especially if multiple thrombotic risk factors are present. For more information see the full GGC guideline Heparin Dose Adjustment, Adult Patients with Very High, or Low Body Weight.
For medical in-patients enoxaparin should be prescribed at 6pm. For surgical in-patients with a significant reduction in mobility, enoxaparin should be prescribed at 6pm the night before surgery, otherwise it should be started after surgery at the later of: 4 hours post-operatively or 6pm. Then at 6pm on subsequent days.
Compared to inpatient surgery, day case surgery generally confers a lower (but not zero) VTE risk. Therefore these patients should be similarly risk assessed for VTE and bleeding risk, and if appropriate anti-embolism stockings (AES) and LMWH prescribed. In patients perceived to be at very high VTE risk, consideration can be given to extending LMWH prophylaxis post discharge.
For patients admitted on the day of surgery who require enoxaparin thromboprophylaxis:
Epidural and spinal anaesthetic techniques should not be carried out within 12 hours of a prophylactic dose of enoxaparin. Likewise epidural catheters should not be removed within 12 hours of a prophylactic dose of enoxaparin. Wait >4 hours after any of these procedures before giving next dose of enoxaparin. In most cases, administration of enoxaparin at 6pm will avoid any difficulties here.
All patients prescribed heparin, including LMWH, should have a baseline platelet count assessed. Heparin-induced thrombocytopenia (HIT) is most commonly seen in post-operative patients receiving unfractionated heparin (UFH). Post-operative patients receiving UFH and post cardio-pulmonary bypass (CPB) patients receiving UFH or LMWH should have platelet count monitoring every 2–3 days from days 4 to 14 or until heparin is stopped. If the platelet count falls to <100 x109/L, or if there is a smaller but significant drop (30–50%) from baseline, stop the heparin and seek specialist advice. Medical and obstetric patients receiving UFH or LMWH, and post-operative patients (excluding post-CPB patients) receiving LMWH, have a low risk of HIT and do not require routine platelet count monitoring for this purpose. Further advice on the diagnosis and treatment of HIT can be found here.
Anti-embolism stockings (AES) are the most commonly used form of mechanical thromboprophylaxis. However, for particularly high thrombosis-risk patients (e.g. immobile acute stroke patients) while LMWH is contraindicated, the use of intermittent pneumatic compression (IPC) devices can provide superior efficacy. There is a GGC protocol for the use of IPC post stroke and this is available in all the GGC stroke units. IPC have similar contraindications as for AES (see below).
Incorrect fitting of AES can be detrimental to the patient causing skin damage. Observation and continual assessment is required.
|Do not offer AES to patients who have:|
|Peripheral arterial disease|
|Peripheral neuropathy of legs|
|Leg / foot ulcers|
|Fragile ‘tissue paper’ skin|
|Major limb deformity (or unusual size or shape of leg) or skin allergy to AES|
|Cellulitis or massive oedema|
|Cautions with AES:|
|Ensure the correct size is provided|
|Re-measuring and refitting may be required|
|Ensure good capillary refill after fitting|
|Show patients how to use AES|
|Ensure patients discharged with AES are able to remove and replace them (or have assistance)|
|Do not fold down the tops of AES|
Guideline reviewed: February 2021
Page last updated: September 2023