ABO discrepancies

What are the most common causes of missing or weak antigens on RBCs in the forward grouping?

A or B subgroups, or disease (leukemia)

What are some common causes of weakly reacting extra antigens in the forward grouping?

Acquired B (from intestinal disease), Rouleaux, cold auto-antibodies, or Wharton's Jelly

Anti-A 4+ Anti-B 2+ A1 Cell 0+ B Cell 4+

Group A with acquired B antigen

What are mixed fields in the forward grouping usually caused by?

Group O transfusions, Stem cell transplants, or A3 or B3 phenotype

Anti-A 0 Anti-B 0 A1 Cell 0 B Cell 0

Missing Isoagglutinins in Group O; could be Group O newborn or elderly patient; may have hypogammaglobulinemia; agammaglobulinemia or taking immunosuppressive drugs Repeat reverse grouping using 4 drops of serum; incubate at room temp. for 30 minutes or at 4C (run autocontrol and screening cells)

What is usually the cause of missing or weak antibodies in the reverse grouping?

Patient is elderly, newborn, immunocomprimised, or all three ;-)

Anti-A 3+ Anti-B 4+ A1 Cell 1+ B Cell 0

Possible cause A2B with anti-A1. Type cells with Anti-A1 lectin, test serum with additional A1, A2, and O cells

Anti-A 4+ Anti-B 0 A1 Cell 1+ B Cell 4+

Probable A2 with anti-A1. Use anti-A1 lectin, test serum against additional A1, A2 and O cells, run auto-control

There are reactions on all cells

Rouleaux (Multiple Myeloma patient): Wash RBCs, use saline replacement. Could also be a cold autoantibody: Perform cold panel and autoabsorb

Anti-A 1+ Anti-B 1+ A1 Cell 1+ B Cell 2+

Weak Reaction in both Forward and Reverse grouping Probable Group O with the following possibilities: 1. Cold Autoantibody 2. Cold Autoantibody and Cold Alloantibody 3. Out of Group Bone Marrow/Stem Cell Transplantation 4. Passively Acquired Antibody

Anti-A 2+mf Anti-B 0 A1 Cell 0 B Cell 4+

Weak Reactions in the Forward grouping (RBC problem) This example is a probable Group A with the following possibilities: 1. Out of Group Transfusion (i.e. Group O units transfused to an A patient.) 2. Out of Group Bone Marrow/Stem Cell Transplantation 3. Leukemia/Lymphoma 4. Fetal-Maternal Bleed 5. A3 Subgroup

Anti-A 4+ Anti-B 4+ A1 Cell 2+ B Cell 2+

Weak Reactions in the Reverse grouping (Patient serum problem). This example is probable Group AB with the following possibilities: 1. Cold Reacting Alloantibody (i.e. Anti-M, Anti-P1 most common) 2. Cold Reacting Autoantibody (i.e. Anti-I, Anti-H, Anti-IH) 3. Passively Acquired Antibody (i.e. plasma exchange, mismatched platelets) 4. Rouleaux