Which laboratory test is considered the best for early detection of acute posttransfusion hemolysis?

The best laboratory test for early detection of acute posttransfusion hemolysis is the visual inspection for free plasma hemoglobin. This test allows for immediate assessment of hemolysis by observing the color changes in the plasma. In cases of acute hemolysis, free hemoglobin is released into the plasma, which can cause a pink to red discoloration. This visual change can alert the laboratory personnel to a potential hemolytic reaction much quicker than other tests.

While other tests like plasma haptoglobin concentration, examination for hematuria, and serum bilirubin concentration can provide useful information, they typically reflect the hemolytic process after some time has elapsed. For example, haptoglobin levels may drop in the presence of elevated free hemoglobin, but this change takes longer to manifest. Similarly, bilirubin levels may rise as a result of the breakdown of hemoglobin, but this occurs after the hemolysis has already started. Hematuria indicates the presence of blood in urine and is not a specific marker for posttransfusion hemolysis. Therefore, visual inspection for free plasma hemoglobin stands out as the most immediate and reliable method for detecting acute hemolytic reactions.