Venous Thromboembolism: Introduction

Overview and Implications

Venous Thromboembolism (VTE) is the third most common cause of vascular mortality worldwide and comprises deep-vein thrombosis (DVT) and pulmonary embolism (PE) (Nicholson, et al., 2020). DVT occurs when an abnormal blood clot forms inside a vein deep in the leg. DVT may cause leg pain and/or swelling but is often clinically silent. PE occurs when all or part of a DVT breaks away from its site in a vein and travels through the venous system to lodge in the lungs. PE may cause chest pain, shortness of breath, tachycardia, hemoptysis, or pre-syncope but is often clinically silent. In clinical practice, about two-thirds of VTE episodes manifest as DVT and one-third as PE with or without DVT (Nicholson, et al., 2020).  

About 50 per cent of all VTE events occur because of a current or recent hospital admission for surgery or acute medical illness. Hospital-acquired VTE is preventable, with interventions including anticoagulants and mechanical measures, including compression stockings and intermittent pneumatic compression (Schünemann et al., 2018). In addition, VTE remains an important cause of maternal morbidity and mortality in Canada with an overall incidence of DVT and PE of 12.1 per 10,000 and 5.4 per 10,000 pregnancies, respectively. VTE occurs at a rate of 4.3 per 10,000 pregnancies postpartum (Chan et al., 2014).

Risk Factors

Risk factors for VTE can be subdivided into factors that promote venous stasis, factors that promote blood hypercoagulability, and factors causing endothelial injury or inflammation. A clear understanding of the risk factors for VTE is vital to identify patients at risk of VTE who would benefit from thromboprophylaxis. An individual patient's risk of VTE depends on intrinsic, patient-specific factors (such as genetic risk factors, age, or body mass index) and acquired risk due to the unique context or situation (such as hospitalization, surgery, cancer, or pregnancy). Risk factors are also frequently categorized by "transient vs. persistent" and "major vs. minor" (Nicholson et al., 2020; Chan et al., 2014).

Goal

To prevent VTE in hospitalized adult and obstetrical patients by implementing strategies which increase the use of evidence-based thromboprophylaxis.

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