20 Cell Washing: Automated Method
Principle
The removal of unbound human serum proteins is necessary before the addition of antihuman globulin (AHG) to both direct and indirect antiglobulin tests. This is accomplished by the dilutional effect of washing the red cells several times with isotonic saline.
Related Policies
This procedure applies to all tests that require the addition of AHG to the test.
Procedure
- Label tubes with patient name and test or reagent identification.
- Complete the procedure for each test as described in the particular SOP up until the point that washing is required.
- Turn on the cell washer (on/off toggle switch).
- Place the tubes in the centrifuge carrier (making sure they are balanced) and program the centrifuge for 4 washes (touch “wash” then “4” on the cell washer)
- Touch the “start” button and wait a minute to hear if the tubes are balanced.
- After the last wash cycle, ensure that there is not a lot of residual saline in the tubes.
- Complete the test procedure as described in the relevant SOP.
Notes
- Loss or hemolysis of the red blood cells from improper washing may result in false results.
- Failure to adequately wash can cause false-negative reactions due to neutralization of the AHG reagent by unbound globulins.
- False-negative results may occur if the washing process is delayed or interrupted.