From the Guidelines
Deep Vein Thrombosis (DVT) is caused by a combination of factors, including blood stasis, hypercoagulability, and endothelial injury, which can be triggered by prolonged immobility, injuries to veins, certain medical conditions, hormonal factors, age, obesity, smoking, and family history of blood clots. The most recent and highest quality study, 1, published in 2020, highlights the importance of risk assessment models in identifying patients at high risk of developing VTE. According to this study, the incidence of VTE in hospitalized acutely ill medical patients detected by screening is up to 14.9%.
Risk Factors for DVT
Several factors increase the risk of developing DVT, including:
- Prolonged immobility, such as during long flights, bed rest, or after surgery, as blood flow slows and allows clots to form
- Injuries to veins from surgery or trauma, which can damage vessel walls and trigger clotting
- Certain medical conditions, including cancer, heart failure, inflammatory bowel disease, and inherited clotting disorders
- Hormonal factors, such as pregnancy, hormone replacement therapy, and birth control pills, which can raise risk levels
- Age, with people over 60 facing higher risk
- Obesity, smoking, and family history of blood clots, which are additional risk factors
Underlying Mechanism
The underlying mechanism of DVT involves Virchow's triad: blood stasis (slowed flow), hypercoagulability (increased clotting tendency), and endothelial injury (damage to vein walls). When these factors combine, platelets aggregate and the clotting cascade activates, forming a thrombus that can obstruct blood flow and potentially break loose to cause pulmonary embolism.
Clinical Implications
The clinical implications of DVT are significant, with a high risk of morbidity and mortality. The American College of Chest Physicians recommends that patients with unprovoked DVT be treated with a Vitamin K antagonist for at least 3 months, and that long-term treatment be considered for patients with a first unprovoked episode of proximal DVT, when risk factors for bleeding are absent and good anticoagulant monitoring is achievable, as stated in 1.
Prevention and Management
Prevention and management of DVT involve the use of risk assessment models, pharmacological and nonpharmacological interventions, and optimized management strategies to reduce the risk of hospital-acquired VTE and bleeding, as discussed in 1 and 1.
From the Research
Causes of Deep Vein Thrombosis (DVT)
The causes of DVT are multifactorial and can be triggered by the interaction between acquired and hereditary risk factors 2. Some of the key factors that contribute to the development of DVT include:
- Acquired risk factors such as hip fracture, pregnancy, and immobility
- Hereditary risk factors such as thrombophilias
- Alteration of venous blood flow, which produces endothelial activation and favors the adhesion of platelets and leukocytes
- Interaction between inflammation and hemostasis, which contributes to the activation of coagulation and the formation of a thrombus
Mechanisms Underlying DVT
The mechanisms underlying DVT are complex and involve the concerted interaction of multiple phenomena, including:
- Venous flow and endothelium
- Platelets and leukocytes
- Tissue factor expression and neutrophil extracellular traps formation
- Activation of coagulation and trapping of red blood cells
Risk Factors for DVT
Several studies have identified risk factors for DVT, including:
- Cancer 3, 4
- High platelet count, high leukocyte count, low hemoglobin level, and high-risk gastrointestinal, genitourinary, and lung cancers 4
- Immobility and surgery 2
- Pregnancy and hip fracture 2
Treatment and Prevention of DVT
While the question of what causes DVT is distinct from its treatment and prevention, it's worth noting that various studies have compared the efficacy and safety of different anticoagulants, such as fondaparinux, enoxaparin, and rivaroxaban, in the treatment and prevention of DVT 5, 6, 3, 4. However, these studies do not directly address the causes of DVT.