AUTOAGGLUTINATION
In severe cases of immune mediated hemolytic anemia, the immune destruction of red cells is so blatant that the red cells clump together (because their antibody coatings stick together) when a drop of blood is placed on a microscope slide. Imagine a drop of blood forming not a red spot but a yellow spot with a small red clump inside it. This finding is especially for boding.

LEUKEMOID REACTION
Classically, in IMHA the stimulation of the bone marrow is so strong that even the white blood cells lines (which have very little to do with this disease but which also are born and incubate in the bone marrow along side the red blood cells) are stimulated. This leads to white blood cell counts that are spectacularly high.


COOMB'S TEST (ALSO CALLED A "DIRECT ANTIBODY TEST")
This is a test designed to identify antibodies coating red blood cell surfaces. This test is the current state of the art for the diagnosis of IMHA but, unfortunately, it is not as helpful as it might seem. It can be erroneously positive in the presence of inflammation or infectious disease (which might lead to harmless attachment of antibody to red cell surfaces) or in the event of prior blood transfusion (ultimately transfused red cells are removed from the immune system). The Coomb's test can be erroneously negative for a number of reasons as well. If the clinical picture fits with IMHA, often the Coomb's test is skipped.