After receiving a unit of Red Blood Cells, a patient develops flushing, fever, shaking, and back pain. What is likely shown in laboratory investigations?

The symptoms described—flushing, fever, shaking, and back pain—are indicative of a hemolytic transfusion reaction, which most commonly occurs due to an error in ABO blood group matching. This type of reaction happens when a patient receives red blood cells that are incompatible with their own blood type, leading to the immune system attacking the transfused cells. In laboratory investigations, an error in ABO grouping would show discrepancies between the patient's blood type and the type of red blood cells received, such as the presence of ABO antibodies that react with the transfused cells.

While other options could potentially be relevant in different contexts, they do not align closely with the acute symptoms exhibited. An error in Rh typing usually leads to milder reactions and does not typically cause such immediate and severe symptoms. The presence of anti-Fy^a antibodies could lead to delayed hemolytic reactions in some cases, but would not be expected to present acutely in this scenario. Lastly, the detection of gram-negative bacteria in the blood bag might suggest bacterial contamination, which would present differently and usually with signs of sepsis rather than the classical hemolytic reaction symptoms. Thus, the laboratory investigations showcasing an error in ABO grouping effectively point to the cause of the patients' acute