The advantages in speed and accuracy of the combined Vincent-Coca technic for the grouping and direct matching of blood prior to transfusion have been emphasized in a recent report from the Cincinnati General Hospital.1 Since the adoption of this method as a routine we have relied successfully on one minute macroscopic grouping in more than 3,000 consecutive blood transfusions. However, the serums used during this time have excelled the requirements of Coca's grade I2 (table 1).
The safety of rapid open macroscopic grouping depends entirely on the use of test serums of extremely high hemagglutinin titer. Donors whose serum meets these standards are rare, and finding them is accomplished only after considerable search.
Consequently a method for concentrating the hemagglutinins in serum is highly desirable. Artificial concentration by alternate freezing and thawing has been proposed by Terry.3 The lyophile method of drying serum as reported by Flosdorf
Paul Hoxworth, Earle Mahoney. ARTIFICIAL CONCENTRATION OF TEST SERUMS IN BLOOD GROUPING. JAMA. 1938;111(17):1554. doi:10.1001/jama.1938.72790430001009