In WDDTY vol 5 no 4, , we reported that a third of people in Britain are given the wrong blood for transfusion.
When one of our readers called this into question, we returned to the study and found that the actual result is far more complicated.
In the study, an informal questionnaire sent to 400 hospital hematology laboratories in Britain, one-third of the 245 labs that responded reported multiple incidents in which the patients received the wrong blood. In most cases, the patient was simply given the wrong blood on the ward or the operating room. Of the 111 incidents, six people died and 12 got ill (BMJ, 7 May 1994).
However, since the question about handing out the wrong blood wasn't even asked (but was volunteered by the responding labs), the study concluded that this data "can give only a substantial underestimate of the incidence of important failures in the transfusion process".
Since most were only supplying information from memory, said the report, it would be "surprising if the remaining laboratories had experienced no errors in over two years." The study concluded the wrong blood is given in one of every 6000 red cell units issued.
An accompanying editorial found that most errors found in other studies come from inadequately documenting blood samples or information about which blood to be given to which patient; in a recent study in two London teaching hospitals, a quarter of patients had inadequate information about their blood.