Miscellaneous problems may cause ABO discrepancies, including:
- Cold reacting autoantibodies that result in spontaneous RBC agglutination or a positive direct antiglobulin test (DAT)
- Mixed red blood cell populations due to massive transfusion
- Unexpected alloantibodies unrelated to ABO antigens
- Unexpected ABO isoagglutinins
Examples of Discrepancies:
- Group AB patient massively transfused with type O donor units
- Mixed field agglutination in the forward type can occur in subsequent patient samples.
- Cold reacting autoanti-I, coating patient red blood cells
- Sensitized patient red blood cells could cause discrepancy in the forward type.
- Cold reacting alloantibody such as anti-M
- The prevalence of the M antigen could result in detection on either the A1 or B cells in the reverse type.
- The stimulation of anti-A1 formation in the plasma of a patient with a subgroup of A or AB.
- This can happen as a result of exposure to donor red cells or through pregnancy.
