Blood contains red blood cells, white blood cells, and platelets that transport oxygen, fight infection, and help with clotting. A complete blood count is a common test that uses automated machines to quickly analyze the different components of blood. It provides information about infection, bone marrow function, anemia, and other health issues by counting red blood cells, white blood cells, and platelets. Fecalysis tests analyze stool samples to check for blood, parasites, bacteria, and other digestive issues.