From the Guidelines
The most common origin of pulmonary embolism (PE) is deep vein thrombosis (DVT) in the lower extremities, particularly the deep veins of the thighs and calves, with approximately 70%–90% of thromboemboli arising from this area. This is supported by clinical and autopsy studies, which have consistently shown that the source of thromboemboli is most often found in the inferior vena cava, specifically at the level of the femoral and iliac veins 1. The formation of blood clots in these veins is often due to conditions that promote blood stasis, hypercoagulability, or endothelial injury (Virchow's triad). Some key risk factors for the development of DVT and subsequent PE include:
- Prolonged immobility
- Recent surgery
- Cancer
- Pregnancy
- Hormonal contraceptive use
- Inherited thrombophilias These risk factors can increase the likelihood of blood clot formation in the deep veins of the lower extremities, which can then break free and travel to the lungs, causing a pulmonary embolism. It is worth noting that while other areas, such as the pelvic veins, upper extremities, or right heart chambers, can also be a source of pulmonary emboli, they are less common, with upper extremity venous thrombosis associated with PE in up to 40% of cases 1. Overall, the lower extremities remain the most common origin of pulmonary embolism, highlighting the importance of preventive measures such as early mobilization after surgery and prophylactic anticoagulation in high-risk patients.
From the Research
Origin of Pulmonary Embolism (PE)
- The most common origin of pulmonary embolism (PE) is deep-vein thrombosis (DVT) 2, 3, 4, 5.
- DVT occurs when a thrombus (a blood clot) forms in deep veins of the body, usually in the lower extremities 6.
- Approximately 75% of fatal pulmonary emboli (PE) occur in medical patients, a clinically heterogeneous group of patients 4.
- Pulmonary embolism is the major complication of deep-vein thrombosis (DVT) and has been shown in autopsy studies to account for 5-10% of hospital deaths 4.
Risk Factors for PE
- Risk factors for venous thromboembolism (VTE) include pelvic and lower extremity fractures, and head injury 6.
- Clinical probability assessment helps to identify patients with low clinical probability for whom the diagnosis of venous thromboembolism can be excluded solely with a negative result from a plasma D-dimer test 5.
- Patients with trauma are at increased risk of DVT and subsequent PE because of coagulopathy in patients with multiple trauma 6.
Diagnosis and Treatment of PE
- The diagnosis is usually confirmed with compression ultrasound showing deep vein thrombosis or with chest CT showing pulmonary embolism 5.
- Most patients with venous thromboembolism will respond to anticoagulation, which is the foundation of treatment 5.
- Anticoagulant therapy with intravenous unfractionated heparin or subcutaneous low molecular weight heparin followed by oral anticoagulant treatment for at least 3 months is the treatment of choice for most patients with PE 2, 3.