trombus

Trombus, also spelled thrombus, is a solid mass formed by blood constituents within a vessel or heart chamber, resulting from coagulation and platelet aggregation. It is typically attached to the vessel wall and may partially or completely occlude blood flow. An embolus is a fragment that breaks away and may travel to lodge in a distant site.

Thrombi form in arteries or veins. Arterial thrombi are often platelet- and fibrin-rich and occur in areas of disrupted endothelium, such as from atherosclerosis or vasculitis. Venous thrombi are richer in red blood cells and develop with slow flow or stasis, dehydration, or hypercoagulable states.

Pathophysiology is commonly described by Virchow's triad: endothelial injury, abnormal blood flow (stasis or turbulence), and hypercoagulability. Risk factors include recent surgery, immobilization, cancer, pregnancy, oral estrogen therapy, obesity, smoking, and inherited clotting disorders.

Clinical significance is substantial. Thrombi can cause myocardial infarction or ischemic stroke when located in coronary or cerebral arteries, while venous thrombi can lead to deep vein thrombosis and, if dislodged, pulmonary embolism. Calcified or organized long-standing thrombi can lead to chronic limb ischemia or post-thrombotic syndrome.

Diagnosis relies on imaging and laboratory tests. Doppler ultrasound is standard for suspected deep vein thrombosis; CT or MR angiography can visualize arterial occlusions; D-dimer testing aids screening in appropriate contexts.

Treatment includes anticoagulation with heparin or a direct oral anticoagulant, and longer-term therapy with warfarin or DOACs. In selected cases, thrombolysis or mechanical thrombectomy or surgical thrombectomy may be used. Prevention focuses on risk factor modification and early mobilization.