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A blood clot occurring on the wall of a blood vessel where the endothelium is damaged.



a clot of blood formed during the lumen of a blood vessel or in the heart. In a broader sense, extravascular clots of blood that form during bleeding, as well as clots of lymph in the lymphatics are also called thrombi.

The formation of a thrombus consists of the following stages: agglutination of platelets, coagulation of fibrinogen, agglutination of red blood cells, and precipitation of plasma proteins. Thrombi may be white, red, laminated, or hyaline. A white thrombus consists of platelets, fibrin, and white blood cells and is formed slowly during rapid blood flow, generally in arteries. A red thrombus, in which red blood cells predominate, forms rapidly during slow blood flow, generally in veins. The most common type of thrombus is the laminated thrombus, which has a layered structure and crimped surface and contains fragments of white and red thrombi. It is attached to the endothelium of a blood vessel, generally that of a vein; this differentiates it from a postmortem thrombus. A hyaline thrombus forms in blood vessels of the capillary bed and consists of a homogenized mass of protein.

A thrombus may be parietal or obstructive. A parietal thrombus forms within the heart in endocarditis and heart disease, in large arteries in atherosclerosis, and in veins in thrombophlebitis. As a parietal thrombus grows, it becomes obstructive, generally in small arteries and veins. A thrombus that grows rapidly into the lumen of a vessel is called progressive, and one that originates in cardiac insufficiency is called congestive. A thrombus that forms in aneurysms is called dilatational; one that is unattached within an atrium is called spherical. A thrombus can dissolve or can grow connective tissue, a process called organization. Thin-walled blood vessels may appear in this tissue (canalization), or calcium salts may be deposited (calcification). A thrombus may cause an embolism or may become purulent, a condition accompanied by a thrombobacterial embolism and leading to sepsis.


References in periodicals archive ?
Q My husband is going to have a knee replacement, and a friend mentioned that this procedure can put you at risk for a blood clot.
It is important to keep in mind that the highest risk of blood clots among reproductive-aged women occurs during pregnancy and in the postpartum period, when estrogen levels increase.
She added: "We need urgent action to provide dedicated pathways for risk assessment and management of cancer-associated blood clots.
Blood clots are more likely to form when we are inactive, meaning that one of the best ways to protect yourself is to get on your feet as soon as you can after the surgery--within 12 hours, if possible.
Kate, 32, was unaware she could be at risk of a blood clot when she was taking the contraceptive pill aged 16.
The good news is that blood clots - also known as a deep vein thrombosis - are preventable.
Patients on medical evacuation travel sometimes have conditions that are major risks for intravenous blood clots.
Parts of blood clots can break off and travel to other parts of the body, causing a serious problem in the lungs (pulmonary embolism) or a heart attack or stroke.
In the case of this patient, we initially tried to use cystoscopy to evacuate blood clots, in the hopes that the catheter would not be occluded, and the conservative treatment would be successful if the blood clots were cleared cystoscopically.
ISLAMABAD -- Young professionals are doubling their risk of suffering a potentially life threatening blood clot because they sit working for three hours at a time, eat lunch at their desks and then go home and sit on the sofa, a survey has found.
According to Dr Hosni, up to 14 per cent of patients who recover following orthopaedic surgery have to return to hospital because they develop blood clots, which often break away and travel through the bloodstream, blocking the blood flow to vital organs.
A complication can occur in some cases where part of the blood clot breaks off and travels to the lung.