51 Immediate-spin Crossmatch

Principle

The immediate-spin (IS) crossmatch provides serologic testing to detect ABO incompatibility only. The serologic (AHG) crossmatch is used to test blood group antibodies in the serum/plasma of a recipient to antigens on donor RCs. The RCs are combined with patient serum/plasma to allow antigen-antibody interaction..

Related Policies

This procedure can be used in compatibility testing of all transfusion recipients who lack clinically significant blood group antibodies and have no history of clinically significant antibodies.

Specimen

Serum or plasma may be used. Specimen age must comply with policies and procedures of the institution. CAN/CSA Z902 Blood and Blood Components standards indicate “the sample shall be collected within 96 hr prior to the scheduled transfusion if:

• The recipient has been transfused with a blood component containing RCs within the previous 3 months
• The recipient has been pregnant within the previous 3 months; or
• The recipient’s history is questionable or unavailable

For repeat recipients, the original sample may be used to crossmatch additional units within the 96 hr period following transfusion of the first unit of blood.”

Reagents

1. Isotonic saline
2. Donor RC’s; from segments attached to the units to be transfused.

Procedure

1. Label tubes with patient name and MRN, donor unit number and test identification (XM).
   1. If performing more than one unit label XM1,XM2…..
   2. Prepare a 2-5% red cell suspension of the donor unit segment(s) in isotonic saline.
   3. Add 2 drops of recipient/patient plasma to a clean, labeled tube.
2. Add one drop of donor cell suspension to their respective tubes.
3. Mix well and centrifuge the tubes for 20 seconds. Examine for hemolysis.
4. Re-suspend and read for agglutination.
5. Grade and record test results immediately while holding tubes in hand.

Interpretation

1. Hemolysis or agglutination may indicate the presence of a serologically incompatible crossmatch. This result is interpreted as “incompatible”. Hemolysis is a positive reaction when using a serum sample.
2. Absence of agglutination and hemolysis is a negative test result and indicates a serologically compatible crossmatch. This result is interpreted as “compatible”.

Notes

1. If the immediate spin (IS) crossmatch is performed before the antibody screen has been completed and no agglutination occurs in the crossmatch tubes, they should be kept at room temperature with the patient’s specimen until the antibody screen is read.
2. When the antibody screen is completed, if the results are negative then the crossmatch tubes are discarded. If the antibody screen is positive, the crossmatch tubes should be incubated at 37oC and continued through to the antihuman globulin phase.
3. There are several reasons to continue the crossmatch beyond the immediate spin (IS) phase to the AHG phase:

• • Grouping problems (forward and reverse discrepancy)
  • Rouleaux formation noted in immediate spin crossmatch
  • Identification of or previous identification of antibody (not demonstrable: ie anti-Kell, anti-E, anti-Fya, etc.)
  • unable to identify the antibody
  • grouping problems
  • positive DAT
  • Rh immune globulin is demonstrable