There is a natural disposition—especially among people in an affluent society—to believe that if one thing is good, two or more things are better. This belief is plainly manifested in the practice of laboratory medicine. It is, for example, a well-recognized and frequently deplored habit of some physicians uncertain of a diagnosis to use a shotgun approach, ordering large batteries of expensive tests in the hope of uncovering an abnormal finding. However, not so well known is a similar kind of redundancy among blood transfusion laboratories. There, the serum not only from blood recipients but also from blood donors is examined relentlessly for unexpected RBC antibodies, regardless of serological characteristics or the capability of causing hemolysis in vivo.
It has been known for many years that, when tested at low temperatures, nearly every person's serum contains antibodies capable of agglutinating his own RBCs, as well as those of most other
Giblett ER. Testing, Testing. Arch Intern Med. 1978;138(3):469. doi:10.1001/archinte.1978.03630270079027