Thrombus: Understanding Abnormal Blood Clots and Their Impact

A thrombus is an abnormal blood clot that forms inside a blood vessel (artery or vein), obstructing flow. Unlike physiological clots that stop bleeding after injury, a thrombus forms inappropriately and persists.

Why It's Abnormal

1. Location

Forms within intact vasculature where clotting is not needed.

2. Composition

Contains platelets, fibrin, red/white blood cells—organized layers (lines of Zahn) indicating formation under flow.

3. Obstruction of Blood Flow

Partial or complete blockage causes ischemia. Consequences depend on site:

• Coronary artery → myocardial infarction
• Cerebral artery → ischemic stroke
• Deep leg veins → DVT (risk of pulmonary embolism)
• Pulmonary artery → pulmonary embolism

4. Risk Factors (Virchow's Triad)

• Stasis: Immobility, heart failure, obesity
• Hypercoagulability: Genetic (Factor V Leiden), cancer, pregnancy, hormones, smoking
• Endothelial Injury: Trauma, surgery, catheters, atherosclerosis

5. Uncontrolled Growth & Persistence

Does not resolve naturally; can propagate, embolize, or organize into chronic occlusion.

6. Complications

Embolization (stroke, PE), post-thrombotic syndrome (venous), chronic arterial insufficiency.

Medical Attention Required

Anticoagulation, thrombolysis, or mechanical removal may be needed to restore flow and prevent recurrence.