Blood Type and Crossmatch is essential for the management of all surgical cases as well as critically ill patients. Although red cell membrane contains more than 300 antigens and 20 blood group antigens are known but still the most important Is ABO grouping because most serious mismatch transfusions reactions are usually caused by ABO incompatible blood and invariably.
The individual who lacks particular antigen will have antibodies against that antigen in his/her serum. For example in a person with antigen A on RBC (group A) will have antibodies against B antigen and similarly group B individual will have antibodies against A antigen. The Blood Type and Crossmatch is always done before any surgery, so that the correct type be known in case of any transfusion is required.
The blood type and crossmatch is very important to be determined before any transfusion to avoid any kind of mismatch.
1. ABO-Rh typing (determining blood group): First step is to determine patient’s blood group in which patient’s red cells are tested with serum known to contain antibodies against A or B and red cells are also tested with anti D antibodies to determine Rh +ve or -ve.
2. Cross matching: Patient’s (recipient) serum is mixed with donor cells. It involves three phases. In first phase ABO incompatibility is determined. It takes 1-5 minutes. Second phase determines antibodies of Rh system. It takes 30 minutes. Third phase (indirect antiglobulin test) determines incomplete antibodies of other system like Kell, Duflt etc.
3. Antibody screening: It is done in both donor and recipient plasma to detect antibodies known to cause non-ABO hemolytic reactions.
Type and Crossmatch
Type and Crossmatch is the technique in which ABO Rh typing (blood grouping) and antibody screening is done along with cross match. This is based on the fact that incidence of haemolytic reactions with only type and screen (without cross match) is less than 1% (0.0 1%). So it is advocated that for surgeries in which chances of transfusion are less than 10% only type and screen is done and if transfusion is required then only cross match should be done.
Emergency transfusion: If there is no time to type and crossmatch blood and to determine ABO group (or there is some problem in determining recipient blood group) then O -ve (universal donor) red cells should be used. O -ve red cells are preferred over O -ve whole blood because it is seen that some O -ve donors may have anti A and anti B antibodies in their plasma.