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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 ?
Blood clots are one of the biggest causes of hospital fatalities, causing 25,000 preventable deaths every year nationwide.
Summary: CAIRO - Venous blood clots (vein thromboembolism or VTE) occurs in 40-60 per cent of patients who are undergoing major orthopaedic surgery, say medical experts.
Within 24 hours of surgery, the CT scan revealed a nearly complete removal of the blood clot.
"In particular, the family feel there are a number of questions concerning the fact that Amanda had been prescribed Dianette tablets prior to the surgery for varicose veins, which are classified as a combined hormonal contraceptive and are known to have an increased risk of blood clots."
Cancer itself may be an underlying factor, but the drugs used to treat it also play a role, says Shenhong Wu, MD, PhD, assistant professor of medical oncology at Stony Brook University Cancer Center and senior author of a recent study linking the anticancer drug bevacizumab (Avastin) with a raised risk of blood clots. "Although they're effective in treating cancer, the mechanism used by some anticancer drugs causes vascular damage that can make blood clots more likely," he says.
The quantity of DNA recovered from the samples therefore appears to be affected by the length of time between the collection of the blood sample and extraction of the DNA, making it important to extract DNA from the blood clot as soon as possible after collection.
A blood clot in the retinal vein of the eye is known as a retinal vein thrombosis.
Blood clots underlie numerous forms of cardiovascular disease, which is the number one killer in the US.
"When applied to a wound, the bandage actually becomes part of the blood clot." After about two minutes the bandage actually seals the wound, and clotting begins.
Around ten people a year die from a blood clot in the lungs within minutes of arriving at Heathrow airport.
The study of 100 air passengers showed that one in 10 developed a blood clot as a result of flying.
Many heart attacks or strokes occur when a blood clot gets stuck in a partially clogged artery.