A comparative study of direct matching techniques in blood transfusion.

The discovery of several new blood-group systems within recent years and the development of new techniques for the detection of antibodies have shown that the time-honoured methods for the direct matching of blood preparatory to transfusion are inadequate and may be dangerously fallacious. Tests in an albumin medium and the use of the indirect Coombs test are the most reliable methods so far developed for detecting incompatibility, and where direct matching which is not urgent is performed in hospital laboratories these procedures should, ideally, always be carried out. (It is, however, realized that this is not yet the case.) Ultimately, perhaps, all direct matching of blood will be carried out by pathologists, blood transfusion officers, and trained technicians working in laboratories equipped for the purpose. At present, however, a great deal of urgent direct tnatching, especially at night, falls to the lot of harassed and relatively inexperienced junior doctors who have neither the time nor the inclination to pursue the niceties of serological technique. Tube tests in albumin cannot satisfactorily be carried out in less than one and a half hours; the indirect Coombs test requires practice and careful controlling to give valid results, and is, essentially, a laboratory test. Neither of these tests, however reliable their results, is therefore wholly satisfactory as a method for use in emergencies or for those who are not experienced in their use. The purpose of this paper is to attempt (1) to show the fallacy of compatibility tests in a saline medium; (2) to demonstrate the reliability of the tube technique of direct matching using an albumin medium; and (3) to explore certain other methods of direct matching, in an endeavour to find a method which will combine speed and simplicity with the greatest possible degree of reliability.