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Venous thromboembolism prophylaxis in the surgical patient
Post-operative VTE prophylaxis is matched to risk (Caprini) against bleeding risk: early mobilisation for all, mechanical measures at low risk, and LMWH at moderate and high risk — and after abdominal or pelvic cancer surgery it is continued for about 4 weeks.
Why it matters in the exam
Questions test matching to risk: a Caprini score of 0 — early mobilisation only; 1–2 — mechanical compression; 3–4 — prophylactic LMWH or heparin (or mechanical when bleeding risk is high); 5 or more — LMWH together with a mechanical measure. The typical dose is enoxaparin 40 mg subcutaneously once daily, and in severe renal impairment (clearance below 30) it is reduced to 30 mg or unfractionated heparin is used. After major abdominal or pelvic cancer surgery LMWH is continued for about 4 weeks, and after joint replacement prophylaxis is also extended.
Two safety points are also asked. The first — regional anaesthesia: after a prophylactic dose of LMWH wait about 12 hours before inserting or removing an epidural catheter, to avoid a spinal haematoma. The second — HIT: a platelet fall of over 50%, 5–10 days after heparin is started, sometimes with thrombosis, requires stopping all heparin (including flushes) and switching to a non-heparin anticoagulant such as argatroban or fondaparinux — and not giving platelets.
Key points
- Caprini: 0 — mobilisation; 1–2 — mechanical; 3–4 — LMWH or heparin; 5 or more — LMWH and mechanical.
- Enoxaparin 40 mg subcutaneously once daily; clearance below 30 — 30 mg or heparin.
- Major abdominal or pelvic cancer surgery — LMWH for about 4 weeks.
- Epidural catheter — about 12 hours after a prophylactic LMWH dose.
- HIT — platelets fall by more than 50% after 5–10 days; stop heparin.
Summary table
| Caprini score | Risk level | Prophylaxis |
|---|---|---|
| 0 | Very low | Early mobilisation |
| 1–2 | Low | Mechanical compression |
| 3–4 | Moderate | Prophylactic LMWH or heparin; mechanical when bleeding risk is high |
| 5 or more | High | LMWH together with a mechanical measure |
| Major abdominal or pelvic cancer surgery | High | LMWH for about 4 weeks after surgery |
| Severe renal impairment (clearance below 30) | — | Enoxaparin 30 mg daily or unfractionated heparin |
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Sources
- American Society of Hematology 2019 guidelines for management of venous thromboembolism: prevention of VTE in surgical hospitalized patients, 2019 — Pharmacological and mechanical prophylaxis
- ACCP Antithrombotic Therapy and Prevention of Thrombosis, 9th edition: Prevention of VTE in Nonorthopedic Surgical Patients, 2012 — Caprini-based risk stratification
- ASRA Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy, 4th edition (2018) — Timing of LMWH and neuraxial procedures
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.