[[Image:Thromboembolus 3.jpg|left|thumb|400px|This is a gross photograph of portions of muscle from the legs including sections of leg veins. Note that the leg veins contain thrombus (arrows). ]]
[[Image:Thromboembolus 3.jpg|left|thumb|400px|This is a gross photograph of portions of muscle from the legs including sections of leg veins. Note that the leg veins contain thrombus (arrows). ]]
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[[Image:Thromboembolus 4.jpg|left|thumb|400px|This is a low-power photomicrograph of lung. A large thrombus is lodged at this branch point in the pulmonary artery. Note the hemorrhage and congestion in the surrounding lung parenchyma.]]
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[[Image:Thromboembolus 5.jpg|left|thumb|400px|This is a photomicrograph of the wall of the pulmonary artery (1) containing the thromboembolus. In this case the artery wall looks normal. If this was a thrombus instead of a thromboembolus, you would expect to see some damage in the artery wall that would have initiated the thrombus. Note the lines of Zahn in the thromboembolus (arrows).]]
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[[Image:Thromboembolus 6.jpg|left|thumb|400px|This is a low-power photomicrograph of the infarcted lung. The tissue is congested and has a very bland appearance due to coagulation necrosis of the lung parenchyma. You can still see the outlines of the alveoli and the cells that make-up the alveoli but there is almost complete loss of nuclei throughout this section.]]
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[[Image:Thromboembolus 8.jpg|left|thumb|400px|This is a gross photograph of cut section of testis from previous image. The tissue is filled with blood. ]]
===Thromboembolism: Bowel Infarction===
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===Thromboembolism: Bowel infarction===
[[Image:Thromboembolus 9.jpg|left|thumb|400px|This is a gross photograph of an opened abdomen at autopsy demonstrating loops of infarcted bowel (arrow). Vascular occlusion can lead to ischemic necrosis of the bowel. In this case, a section of bowel herniated through a fibrous connective tissue band and was strangulated, leading to ischemic necrosis.]]
[[Image:Thromboembolus 9.jpg|left|thumb|400px|This is a gross photograph of an opened abdomen at autopsy demonstrating loops of infarcted bowel (arrow). Vascular occlusion can lead to ischemic necrosis of the bowel. In this case, a section of bowel herniated through a fibrous connective tissue band and was strangulated, leading to ischemic necrosis.]]
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[[Image:Thromboembolus 10.jpg|left|thumb|400px|This is a gross photograph of the fibrous band between the uterus and adjacent tissues. This fibrous scar tissue is probably left over from a previous surgery or an infection. A loop of bowel herniated through the opening produced by this fibrous band and became incarcerated leading to the ischemic necrosis seen in the previous image.]]
[[Image:Coronary thrombosis 1.jpg|left|thumb|400px|This is a gross photograph of thrombosed coronary artery (arrows).]]
[[Image:Coronary thrombosis 1.jpg|left|thumb|400px|This is a gross photograph of thrombosed coronary artery (arrows).]]
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===Artificial Heart Valve Thrombosis===
[[Image:Coronary thrombosis 2.jpg|left|thumb|400px|This is a low-power photomicrograph of thrombosed coronary artery. The thrombus (1) completely occludes the vessel. Note the layering of the thrombus. The fibrous cap is ruptured (arrow) and there is hemorrhage into the atherosclerotic plaque. Note the cholesterol crystals in the plaque.]]
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[[Image:Coronary thrombosis 3.jpg|left|thumb|400px|This is a higher-power photomicrograph of the ruptured fibrous cap (arrows) with hemorrhage (1) into the atherosclerotic plaque.]]
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[[Image:Coronary thrombosis 4.jpg|left|thumb|400px|This is another high-power photomicrograph of the ruptured fibrous cap (arrows) with hemorrhage (1) into the atherosclerotic plaque. Note the presence of cholesterol crystals.]]
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[[Image:Coronary thrombosis 5.jpg|left|thumb|400px|This is a high-power photomicrograph of thrombus attached to the wall of the vessel. There is early organization of the thrombus (arrow). ]]
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[[Image:Coronary thrombosis 6.jpg|left|thumb|400px|This is a higher-power photomicrograph of thrombus attached to the wall of the vessel. Note the early organization with in-growth of fibroblasts and small blood vessels from the wall of the artery (arrows).]]
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[[Image:Coronary thrombosis 7.jpg|left|thumb|400px|In this low-power photomicrograph of another coronary artery from this patient, a mural thrombus has undergone re-organization. The mural thrombus has been invaded by the in-growth of fibroblasts and small blood vessels from the wall of the artery. The thrombotic material has been phagocytosed and removed by macrophages and is replaced by fibrous connective tissue and blood vessels. This re-organized thrombus still compromises the lumen of this vessel. ]]
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[[Image:Coronary thrombosis 8.jpg|left|thumb|400px|This is a higher-power photomicrograph of the vessel wall. The adventitia (1) and the media (2) contain inflammatory cells. The recanalized portion of the vessel is composed of fibrous connective tissue and contains numerous small blood vessels. There is a small area of hemorrhage (arrow) in the central portion of this image.]]
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[[Image:Coronary thrombosis 9.jpg|left|thumb|400px|This is a higher-power photomicrograph of another region of the vessel wall. The adventitia (1) and the media (2) contain inflammatory cells. The recanalized portion of the vessel (3) is composed of fibrous connective tissue and contains numerous small blood vessels (arrows). ]]
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[[Image:Coronary thrombosis 10.jpg|left|thumb|400px|This is a high-power photomicrograph of the luminal surface of a re-canalized vessel. Note that the vessel lumen is lined by endothelial cells (arrows). ]]
The formation of a thrombus is usually caused by the top three causes, known as (Virchow's triad): (Classically, thrombosis is caused by abnormalities in one or more of the following)
an injury to the vessel's wall (such as by trauma, infection, or turbulent flow at bifurcations);
by the slowing or stagnation of blood flow past the point of injury (which may occur after long periods of sedentary behavior (for example, sitting on a long airplane flight);
A 67-year-old male was hospitalized because of extensive atherosclerotic cardiovascular disease. Following surgery, during which diseased portions of the femoral arteries were bypassed, he developed massive pulmonary embolism and expired. At autopsy, thrombi were found in the femoral and iliac veins, as well as in the larger pulmonary arteries.
↑Kuipers S, Cannegieter SC, Middeldorp S, Robyn L, Büller HR, et al. The Absolute Risk of Venous Thrombosis after Air Travel: A Cohort Study of 8,755 Employees of International Organisations PLoS Medicine Vol. 4, No. 9, e290 doi:10.1371/journal.PMID 0040290