The UK National External Quality Assessment Scheme in Blood Group Serology. ABO and D grouping and antibody screening 1982-1983.

In seven surveys of blood grouping the overall rates of major error were 0.12% and 0.37% for uncomplicated ABO and D grouping respectively. Of 17 errors of ABO grouping, 13 were errors of transposition or interpretation and four were apparently technical. Of 52 errors of D grouping, 20 appeared to be errors of transposition or interpretation and 32 were apparently technical. Of the 32 technical errors of D grouping, 31 were D-negative grouped as Du (29) or D-positive (2) and most of these errors were due to misgrouping in the antiglobulin test. Causes of error in D grouping by antiglobulin test include anti-Bg and other contaminating immune antibodies, residual unabsorbed anti-A and the inherently high rate of false positive results obtained in the antiglobulin test. In view of the lack of benefit of Du testing to blood recipients or to pregnant women and of the possible adverse consequences of misgrouping D-negative patients as Du or D-positive, it is recommended that Du testing be abandoned in these groups of patients. The surveys of antibody screening demonstrated lack of standardisation and error rates similar to those previously reported in the UK for compatibility testing.