Venous Thromboembolism

Venous thromboembolism (VTE) is the disease spectrum comprising deep vein thrombosis (DVT) and pulmonary embolism (PE) — a thrombus forming in the deep veins, usually of the legs, that may dislodge and travel to the pulmonary arteries. It is a leading cause of preventable death in hospitalised and surgical patients and a major concern in the perioperative period.

Definition

Venous thromboembolism is thrombus formation within the venous system — deep vein thrombosis when the clot lodges in a deep vein and pulmonary embolism when thrombus reaches the pulmonary arteries — treated as a single disease entity because the two manifestations share mechanisms, risk factors, and management.

Scope

The entry covers the conceptual unity of DVT and PE as one disease continuum, the predisposing factors summarised by Virchow's triad, the surgical and hospital settings that raise risk, and the broad principles of prevention and anticoagulant treatment. It is a reference overview rather than individualised clinical guidance, and the perioperative angle is its place within surgery.

Key concepts

• Deep vein thrombosis (DVT)
• Pulmonary embolism (PE)
• Virchow's triad (stasis, hypercoagulability, endothelial injury)
• Provoked versus unprovoked VTE
• Perioperative and hospital-acquired risk
• Thromboprophylaxis
• Anticoagulation

Mechanisms

Venous thrombosis is classically explained by Virchow's triad: blood stasis, a hypercoagulable state, and endothelial injury. Surgery and immobilisation contribute stasis and a transient procoagulant response, while inherited or acquired thrombophilia and cancer add hypercoagulability. A thrombus that forms in a deep vein may propagate and embolise: fragments carried through the right heart lodge in the pulmonary arteries, obstructing flow and, if large, impairing right-ventricular function. Prevention and treatment act on coagulation through mechanical measures and anticoagulant drugs.

Clinical relevance

VTE is a major cause of preventable morbidity and death around surgery and hospitalisation, which is why risk assessment and prophylaxis are embedded in perioperative care, and why understanding its mechanisms supports critical reading of prevention evidence. This entry is educational and does not specify dosing, individual risk thresholds, or treatment decisions.

Epidemiology

VTE incidence rises sharply with age and is increased by surgery, trauma, immobilisation, cancer, pregnancy and the postpartum period, hormonal therapy, and inherited thrombophilias. It is among the most common preventable causes of hospital-associated death, and a proportion of cases are unprovoked, occurring without an identifiable transient trigger.

History

Rudolf Virchow's nineteenth-century work on the components of thrombosis gave the field the conceptual triad that still organises its understanding of risk. The twentieth century introduced heparin and vitamin-K-antagonist anticoagulation, and more recently direct oral anticoagulants, reshaping both prophylaxis and treatment and the guideline frameworks that govern them.

Debates

Duration of anticoagulation after unprovoked VTE

Whether to stop anticoagulation after an initial treatment period or continue it indefinitely after unprovoked VTE balances the recurrence risk against bleeding risk, and remains an area where guideline recommendations are individualised rather than uniform.

Key figures

• Rudolf Virchow

Seminal works

• heit-2015-epi
• goldhaber-2012-pe-dvt
• konstantinides-2020-esc

Frequently asked questions

Why are DVT and PE considered one disease?

Because pulmonary embolism usually arises from a deep vein thrombosis that has dislodged and travelled to the lungs, the two share the same underlying clotting mechanisms, risk factors, and treatment, so they are grouped together as venous thromboembolism.

Why is VTE such a concern after surgery?

Surgery and the immobility that follows it combine the elements of Virchow's triad — venous stasis, a procoagulant state, and vascular injury — which raises clotting risk, making VTE a leading preventable complication of the perioperative period.