In a patient recovering from colon cancer, ABO grouping shows a discrepancy. What is the most likely cause?

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Multiple Choice

In a patient recovering from colon cancer, ABO grouping shows a discrepancy. What is the most likely cause?

The main idea is that cancer can change how ABO antigens are displayed on red blood cells. In colon cancer, there can be downregulation or alteration of the enzymes that build A and B antigens, so the density of these antigens on the red cell surface becomes weaker. When anti-A and anti-B reagents are used for typing, the reactions may be faint or even negative, producing a discrepancy between forward typing (cell) and reverse typing (serum). This reduced antigen expression from the cancer is the most likely explanation for the ABO discrepancy. Other options don’t address this cancer-related change in antigen expression. Temperature-based adjustments or saliva secretor testing don’t explain weakened A and B antigen density, and absorption-elution is a testing technique to identify antibodies bound to cells rather than a cause of antigen weakening.

The main idea is that cancer can change how ABO antigens are displayed on red blood cells. In colon cancer, there can be downregulation or alteration of the enzymes that build A and B antigens, so the density of these antigens on the red cell surface becomes weaker. When anti-A and anti-B reagents are used for typing, the reactions may be faint or even negative, producing a discrepancy between forward typing (cell) and reverse typing (serum). This reduced antigen expression from the cancer is the most likely explanation for the ABO discrepancy.

Other options don’t address this cancer-related change in antigen expression. Temperature-based adjustments or saliva secretor testing don’t explain weakened A and B antigen density, and absorption-elution is a testing technique to identify antibodies bound to cells rather than a cause of antigen weakening.

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