Anaes · Patient safety
Venous thromboembolism prophylaxis
Also known as VTE prophylaxis · Thromboprophylaxis · DVT prophylaxis · ASRA timing · Neuraxial anticoagulation · LMWH epidural
Exam-exhaustive perioperative VTE prophylaxis: risk stratification, mechanical and pharmacological options, extended prophylaxis after major ortho/cancer surgery, and ASRA timing principles with neuraxial anaesthesia and catheter removal for ANZCA Final and equivalents.
Checked against its sources on 14 Oct 2026
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Red flags
- Spinal epidural haematoma is the catastrophic interaction between anticoagulants and neuraxial anaesthesia — time puncture and catheter removal to ASRA windows.
- Prophylactic LMWH: typically ≥12 h after last dose before neuraxial; restart ≥4 h after catheter removal (confirm current ASRA table and renal function).
- High-VTE patients (major ortho, major cancer, prior VTE, high Caprini) need pharmacological ± extended prophylaxis — mechanical alone is not enough if bleeding risk allows.
- High-bleeding patients: mechanical bridge first, then anticoagulate when safe.
- Renal impairment: LMWH/DOAC/fondaparinux accumulate — dose-adjust or use UFH.
Meet the patient
An older woman for a total hip replacement is on evening prophylactic enoxaparin for VTE prophylaxis, and the surgeon has requested a spinal for analgesia. The question that decides her night is the ASRA window: is the trough interval long enough, and when does the next dose go in after the catheter comes out?[1]
Two ideas frame every VTE decision: the bleeding risk and the clot risk are weighed against each other, never in isolation, and the neuraxial needle and the epidural catheter are as dangerous as any anticoagulant — both insertion and removal are high-risk moments. Hold those two and the protocol reads itself.[1]
References8ShowHide
- [1]Kopp SL, Vandermeulen E, McBane RD, et al. Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine Evidence-Based Guidelines (fifth edition) Reg Anesth Pain Med, 2025.PMID 39880411
- [2]Pannucci CJ, Swistun L, MacDonald JK, et al. Individualized Venous Thromboembolism Risk Stratification Using the 2005 Caprini Score to Identify the Benefits and Harms of Chemoprophylaxis in Surgical Patients: A Meta-analysis. Annals of surgery, 2017.PMID 28106607
- [3]Choi JDW, et al. The efficacy and safety of extended thromboprophylaxis after colorectal surgery: a systematic review and meta-analysis Int J Colorectal Dis, 2025.PMID 41065855
- [4]Riediger C, et al. Aspirin for Venous Thromboembolism Prevention in Orthopaedic Surgery with Focus on Trauma and Arthroplasty: A Structured Evidence-Based Review of Randomised Trials, Guidelines, and Contemporary Practice Considerations J Clin Med, 2026.PMID 42355718
- [5]Kakkos SK, et al. Combined intermittent pneumatic leg compression and pharmacological prophylaxis for prevention of venous thromboembolism. Cochrane Database Syst Rev, 2016.PMID 27600864
- [6]Hayssen H, Cires-Drouet R, Englum B, et al. Systematic review of venous thromboembolism risk categories derived from Caprini score. Journal of vascular surgery. Venous and lymphatic disorders, 2022.PMID 35926802
- [7]Horlocker TT Regional anaesthesia in the patient receiving antithrombotic and antiplatelet therapy. British journal of anaesthesia, 2011.PMID 22156275
- [8]Bos EME, Haumann J, de Quelerij M, et al. Haematoma and abscess after neuraxial anaesthesia: a review of 647 cases. British journal of anaesthesia, 2018.PMID 29576110