Correlation of the echogenicity and structure of clotted blood.

The echogenicity of clotting human blood in sterile plastic bags was studied for up to 21 days and correlated with the histology of the clots. As observed with a 6-MHz A-scanner and a 5-MHz real-time gray-scale scanner, fresh blood and fresh clots were rich in internal echoes. The blood clot gradually became anechoic as a result of erythrocyte packing, hemolysis, and formation of fibrin thrombus, except for the irregular upper border, which also remained histologically inhomogeneous. This study shows that the echogenicity of a hematoma or clot is dependent on its histology; namely, on the distribution and integrity of cells within the clot.