Erythroblastosis fetalis due to factor c(hr'); a practical method for investigating sensitization to Rh subgroup factors.

Erythroblastosis fetalis (hemolytic disease of the newborn) is a disease wherein the clinical laboratory attains special achievement, inasmuch as the diagnosis, prognosis, and prescription for therapy may be provided by means of laboratory procedures. As a matter of fact, a great deal may be accomplished prior to the birth of the patient. Thus, it seems worthwhile to re-emphasize 2 points that are pertinent to this problem in the average clinical laboratory: 1. The staff of the laboratory should be prepared for a practical solution to the problem when the disease is the result of factors other than D(Rh0). Allen 1 estimated that AB, K, c, E, and C factors account for approximately 20 per cent of all instances of erythroblastosis fetalis. Recent papers u indicate that ABOincompatibility may be the cause of erythroblastosis fetalis more frequently than previously recognized, but most of these patients have only a slight degree of disease that might be overlooked. Even the obvious clinical cases pose a vexing diagnostic problem that will not be discussed in this paper. 2. The cross-matching procedure should include technics that enable detection of incompatibilities of minor groups. This is highly important, owing to the fact that the routine procedures for typing usually include the identification of only 3 of at least 16 blood factors that are clinically significant, and cross-matching is relied upon for the detection of incompatibility from the other factors. This paper deals with a case of erythroblastosis fetalis that resulted from sensitization to c(hr') factor; a delay in accurate diagnosis and adequate therapy was attributable to the use of an unreliable cross-matching technic that is used rather commonly. Further studies with methods that may be used in the average clinical laboratory revealed that sensitization to c(hr') factor was the underlying cause of the erythroblastosis.