- Thrombosis is a pathological process in which a blood clot, or thrombus, forms within a blood vessel and obstructs the normal flow of blood. While clot formation is a natural and vital defense mechanism to stop bleeding after vascular injury, thrombosis refers to inappropriate or excessive clotting that occurs inside intact blood vessels.
- Depending on the site of occurrence, thrombosis can be classified into arterial thrombosis, which typically affects arteries and is associated with conditions like myocardial infarction and ischemic stroke, and venous thrombosis, which develops in veins and includes deep vein thrombosis (DVT) and pulmonary embolism (PE). Both forms are major causes of morbidity and mortality worldwide.
- The underlying mechanisms of thrombosis are classically described by Virchow’s triad, which includes three interrelated factors: endothelial injury, abnormal blood flow, and hypercoagulability. Endothelial injury, such as that caused by atherosclerosis, hypertension, or trauma, can trigger platelet adhesion and clot formation. Abnormal blood flow, including turbulence in arteries or stasis in veins, further promotes thrombus development. Hypercoagulability refers to an increased tendency of the blood to clot, which may result from inherited disorders (e.g., Factor V Leiden mutation, prothrombin gene mutation) or acquired states such as cancer, pregnancy, obesity, prolonged immobility, or use of certain medications like oral contraceptives.
- The clinical consequences of thrombosis vary according to location and extent. Arterial thrombosis often leads to sudden obstruction of blood supply, causing acute ischemia of tissues or organs. This is the mechanism behind heart attacks, strokes, and limb ischemia. Venous thrombosis, on the other hand, typically manifests with swelling, pain, redness, and warmth of the affected limb, but its most feared complication is pulmonary embolism, in which a fragment of the thrombus breaks off and travels to the lungs, potentially causing sudden death. Chronic complications may also arise, including post-thrombotic syndrome or chronic thromboembolic pulmonary hypertension.
- Diagnosis of thrombosis relies on clinical suspicion supported by laboratory and imaging tests. For venous thrombosis, D-dimer assays and duplex ultrasonography are widely used, while arterial thrombosis is often confirmed through angiography or imaging such as CT or MRI scans. Risk assessment tools and scoring systems help determine the likelihood of thrombosis in suspected cases, guiding decisions on further investigation and treatment.
- Management typically involves anticoagulation therapy, which prevents clot extension and reduces the risk of recurrence. Direct oral anticoagulants (DOACs), heparins, and warfarin are the main pharmacological agents used. In some arterial cases, antiplatelet agents like aspirin or clopidogrel are prescribed, as platelets play a key role in arterial clotting. Severe cases may require thrombolytic therapy (clot-dissolving drugs) or surgical procedures such as thrombectomy or stent placement to restore blood flow. Long-term prevention strategies target underlying risk factors through lifestyle modifications, control of hypertension, diabetes, and hyperlipidemia, and prophylactic anticoagulation in high-risk settings such as surgery or hospitalization.
- Overall, thrombosis is a complex and multifactorial condition with potentially life-threatening consequences. Advances in early detection, risk assessment, and treatment have significantly improved outcomes, but prevention remains the most effective strategy. Public health measures that encourage regular physical activity, smoking cessation, balanced diet, and appropriate medical screening are essential in reducing the global burden of thrombotic diseases.
