For most patients the antibody screen is negative and the crossmatch is compatible. When a pretransfusion test is positive then the cause must be found after considering the possible explanations.
Pretransfusion tests:
(1) antibody screen
(2) patient (recipient) autocontrol
(3) crossmatch (immediate spin to antiglobulin phase)
|
Antibody Screen |
Patient Autocontrol |
Crossmatch |
Group |
|
negative |
negative |
incompatible on immediate spin |
1 |
|
negative |
positive |
incompatible on immediate spin |
2 |
|
negative |
negative |
incompatible in antiglobulin phase |
3 |
|
negative |
positive |
incompatible in antiglobulin phase |
4 |
|
positive |
NA |
compatible |
5 |
|
positive |
negative |
incompatible |
6 |
|
positive |
positive |
incompatible |
7 |
Group 1:
(1) donor cells ABO-incompatible due to error (with donor unit or patient specimen)
(2) donor cells ABO-incompatible due to failure to detect weak antigenic expression
(3) anti-A1 in serum of A2 or A2B patients
(4) alloantibodies reactive at room temperature
(5) donor cells polyagglutinable
Group 2:
(1) rouleaux
(2) cold autoantibody
Group 3:
(1) donor cells with positive DAT
(2) weak alloantibody reacting with strong expression of antigens on donor cells (and no or weak expression on screener cells)
(3) antibody to low incidence antigen on donor cells
(4) passively transferred antibody to recipient (anti-A or anti-B from ABO-incompatible platelets – screener cells are O-negative)
Group 4:
(1) warm autoantibody
Group 5:
(1) autoantibody (anti-H or anti-IH)
(2) anti-Le(BH)
(3) reagent-related problem
(4) alloantibody with donor unit negative for antigen or showing weak antigenic expression
Group 6:
(1) alloantibodies
(2) reagent-related problem
Group 7:
(1) transfusion reaction in progress in recipient
(2) passively transferred alloantibody
(3) autoantibody (cold or warm)
(4) rouleaux
(5) reagent-related problem
Specialty: Clinical Laboratory
