Photography Today I bring to you Direct Antiglobulin Testing (DAT). This is a pretty simple immunohematology test performed in certain circumstances. Some Blood Banks still include them with all crossmatches, but that's really an outdated practice. So, players in this test are of course the red blood cell (RBC) and IgG Antibodies. The DAT detects RBC's that are bound with IgG Antibodies. One drop of the patients RBC's are placed into a glass test tube. They are then washed 3 to 4 times with normal saline. (Yes, quite literally washed, okay more like rinsed since there's no soap involved) One drop of Anti-human globulin is added. The tube is then centrifuged for 15 seconds and then "read". (Using a mirror we re-suspend the cell button and visually observe the presence or absence of agglutination [clumping]). If agglutination is observed the test is positive....