The presence of flank pain and hypotension after a blood transfusion is indicative of which reaction?

• A. Febrile non-hemolytic reaction
• B. Acute hemolytic reaction
• C. Hyperacute reaction
• D. Delayed hemolytic reaction

Answer: (B)

Flank pain and hypotension occurring after a blood transfusion are hallmark signs of an acute hemolytic reaction. This type of reaction often results from ABO blood group incompatibility, where the recipient's immune system responds to the transfused red blood cells as foreign. The rapid destruction of these cells leads to the release of hemoglobin and other intracellular components into the circulation. This can cause significant cardiovascular instability, resulting in hypotension. Flank pain often arises from kidney damage due to the hemolysis and the subsequent release of free hemoglobin, which can lead to renal tubular obstruction and acute kidney injury.

In contrast, febrile non-hemolytic reactions are usually characterized by fever and chills without the severe systemic manifestations seen in acute hemolytic reactions. Hyperacute reactions, while also serious, are rare and typically occur almost immediately after transfusion due to pre-existing antibodies—usually in cases of organ transplantation rather than blood transfusion. Delayed hemolytic reactions can occur days to weeks after a transfusion and are less likely to present with acute flank pain and hypotension.

Overall, the combination of flank pain and hypotension specifically points towards an acute hemolytic reaction as the cause, emphasizing the need for careful monitoring during and