Fat embolism is the blockage of blood vessels by fat globules. The emphasis is on blockage which separates fat embolism from lipaemia in which the plasma fat is a fine emulsion readily passing the smallest capillaries. Embolism by fat has features different from other forms of embolism: it is predominantly a microembolism affecting the minute vessels, especially capillaries and arterioles; the emboli are fluid and deformable. Hence, the vascular occlusion is likely to be temporary."