Venous thromboembolism (VTE) prophylaxis

Last reviewed: 28 Feb 2023
Last updated: 05 Oct 2022



History and exam

Key diagnostic factors

  • previous VTE, thrombophilia, malignancy, postoperative setting, trauma, and indwelling central catheter
  • chronic medical conditions, paresis, increasing age, obesity, estrogen-containing birth control pills and hormone replacement therapy, varicose veins, pregnancy and up to 6 week postpartum, first-degree relative with a history of VTE, extended travel, and admission to intensive care
More key diagnostic factors

Risk factors

  • previous VTE (deep vein thrombosis [DVT] and/or pulmonary embolism [PE])
  • thrombophilia
  • malignancy
  • postoperative setting
  • trauma
  • indwelling central catheter (upper or lower extremity)
  • immobility
  • myeloproliferative diseases
  • congestive heart failure
  • chronic obstructive pulmonary disease
  • inflammatory bowel disease
  • neurologic disease with extremity paresis
  • increasing age
  • obesity
  • estrogen-containing birth control pills, hormone replacement therapy (HRT), and androgen deprivation therapy
  • history of varicose veins
  • pregnancy/postpartum
  • extended travel
  • lower leg immobility
  • first-degree relative with a history of VTE
  • admission to intensive care
More risk factors

Diagnostic investigations

1st investigations to order

  • CBC
  • serum creatinine
  • INR
  • PTT
More 1st investigations to order

Investigations to consider

  • serum antiplatelet factor 4 antibodies
More investigations to consider

Treatment algorithm


all at-risk patients


trauma patients

surgical patients

medical patients



Nathalie Routhier, MD, MSc, FRCPC

Attending Physician

Assistant Professor

University of Montreal




NR declares that she has no competing interests.

Vicky Tagalakis, MD, FRCPC, MSC
Vicky Tagalakis

Associate Professor

General Internal Medicine Program Director

McGill University Division of Internal Medicine

Centre for Clinical Epidemiology of the Lady Davis Institute for Medical Research

Jewish General Hospital




VT declares that she has received an investigator-initiated grant from Sanofi-Aventis. She has also received consultancy fees from and given lectures sponsored by Bristol-Myers Squibb, Pfizer, Sanofi-Aventis, and Servier. VT is an author of references cited in this topic.

Farah Zarka,

Vasculitis Clinic

Department of Medicine

Hôpital du Sacré-Coeur de Montréal

University of Montreal




FZ declares that she has no competing interests.


Dr Nathalie Routhier, Dr Vicky Tagalakis and Dr Farah Zarka would like to gratefully acknowledge Dr Vincent Bouchard-Dechêne and Dr Adi J. Klil-Drori, previous contributors to this topic.


VBD and AJKD declare no competing interests.

Peer reviewers

Andrew Parfitt, MBBS, FFAEM

Clinical Director

Acute Medicine

Associate Medical Director

Consultant Emergency Medicine

Guy's and St Thomas' NHS Foundation Trust

Clinical Lead and Consultant

Accident Emergency Medicine

St Thomas' Hospital




AP declares that he has no competing interests.

Sudeep Shivakumar, MD


Thrombosis Fellow

University of Ottawa

Ottawa Health Research Institute




SS declares that he has no competing interests.

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