major crossmatching

Question 1

what is the principle?

Answer 1

make use of patient’s serum mixed with donor’s RBC to detect antibodies in the patient’s serum that may possibly damage or destroy the donor’s RBC

Question 2

a clotted or anticoagulated blood drawn within — of testing may be used

Answer 2

72 hours

Question 3

why fresh serum must be used?

Answer 3

to assure presence of adequate complement and calcium

Question 4

why if plasma is used?

Answer 4

complement-dependent antibodies may not be detected

Question 5

enumerate the phases

Answer 5

• immediate spin | saline phase
• incubation at 37C | saline phase
• antiglobulin phase

Question 6

enumerate the reagents used during protein phase

Answer 6

• 22% bovine albumin
• LISS
• PEG

Question 7

cell suspension required

Answer 7

2-5% RBC suspension

Question 8

enumerate the immediate/saline phase

Answer 8

1. add 2 drops of patient serum in a 5 ml test tube
2. add 1 drop of 2-5% donor’s red cells
3. mix and spin for 15 secs at 3400 rpm
4. read for agglutination or hemolysis

Question 9

enumerate the procedure in protein phase

Answer 9

1. add 2 drops 22% bovine albumin | LISS PEG
2. mix and incubate @37C for 15-30 mins
3. centrifuge for 15 seconds then observe for hemolysis or agglutination

Question 10

enumerate tha antiglobulin phase

Answer 10

1. wash 3-4 times with NSS
2. add 2 drops of AHG reagent
3. centri for 15 secs @3400 rpm
4. read and observe for agglutination or hemolysis
5. test all negative test results with check cells

Question 11

hemolysis or agglutination indicates?

this is interpreted as?

Answer 11

presence of an antibody directed against the corresponding antigen which is present on the donor cells.

INCOMPATIBLE

Question 12

no agglutination or hemolysis indicates

this is interpreted as?

Answer 12

absence of an antigen/antibody present in the donor’s RBC and patient’s serum

COMPATIBLE

Question 13

3 procedures of crossmatching

Answer 13

1. pre-serologic
2. serological
3. post-serological