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[[File:NationWide Logo.jpeg|right|link=https://www.nwlabs.co.uk/|alt=NationWide Logo|240x240px|frameless]]
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== Introduction ==
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Crossmatching assesses the effect of recipient serum antibodies on donor cells (major crossmatch) and the effect of donor serum antibodies on recipient blood cells (minor crossmatch).
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It is important to note that a compatible crossmatch does not completely eliminate the possibility of a transfusion reaction. Low antibody titre may not be detected via a cross match procedure.
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== Protocol ==
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Numerous crossmatching methods have been described and vary in their ease/speed and sensitivity. An example protocol suitable for the clinical setting is as follows:
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* Take 2ml of donor blood and 2ml of recipient blood, each into EDTA +/- serum (not a gel tube) The option exists to submit these to the laboratory for crossmatching
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* Centrifuge for 5-10 minutes (usually at around 3000rpm) and harvest the plasma. Transfer 1 drop of concentrated cells to 3ml of isotonic saline and re-suspend
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* Wash the cells in each sample 3 x in isotonic saline, filling the tubes with saline, mixing, centrifuging, and decanting
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* Finally re-suspend the cells in 3ml isotonic saline giving approximately a 2.5-5% suspension (‘weak’ tomato juice)
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* Into two tubes (or microtitre wells) mix:
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{| class="wikitable"
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|+
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|Tube 1 (major
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crossmatch)
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|Donor cells (in isotonic saline) and recipient plasma in equal
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volumes (2 drops of each)
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|-
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|Tube 2 (minor
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crossmatch)
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|Recipient cells (in isotonic saline) and donor plasma in equal
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volumes (2 drops of each).
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|}
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* Incubate both tubes at 37°C for 1 hour. This incubation period can be reduced in an emergency situation, however, this will reduce the sensitivity of the test
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* Examine the tubes for any visible haemolysis or agglutination. Additionally, place one drop of fluid from each tube onto a microscope slide and examine microscopically for agglutination
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== Interpretation ==
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* The end point for a crossmatching is considered to be visible haemagglutination, if this is observed, an incompatibility exists
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Please visit www.nwlabs.co.uk or see our current price list for more information
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== Authors & References ==
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[[NationWide Laboratories]]

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