Clinical History:
An 85-year-old woman fell and broke her hip. She was not a good candidate for surgery, so she was confined to bed in a nursing home. Several weeks later, she was being moved to another room and soon afterwards became short of breath. She died soon after. At autopsy, a large pulmonary embolus was found.
The vein on image 10 is from the pelvis. This vein (which is distinguished from artery by the thin muscular wall and lack of elastic lamina) is completely occluded by thrombus. Part of the thrombus is old and shows evidence of organization (note the granulation tissue). Part of the thrombus is recent, with layering of blood and fibrin.
Image 14 shows a large branch of the main pulmonary artery that is partially occluded by an embolus. The surrounding lung does not show infarction, but there is pulmonary edema (pink homogenous material in the
alveolar spaces).
- What are risk factors for venous thrombosis?
Such factors include: stasis (from lack of movement in immobilized patients), hypercoagulability from increased age, smoking, oral contraceptives,
congenital anticoagulant deficiencies (which generally appear at a younger age), and some neoplasms, and abnormalities of the vessel wall (endothelial injury) from trauma and inflammation.
- Where do most pulmonary emboli originate?
Most originate in the deep veins of the pelvis and the legs. Thrombi rarely form in the veins the the upper extremities.
- How do you distinguish a premortem thrombus from postmortem blood clot?
A premortem thrombus shows layering of the blood and fibrin (lines of Zahn) and will attach to the vessel wall and organize over time.
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