Visual inspection of stored canine blood for hemolysis compared with measured plasma-free hemoglobin to assess suitability for transfusion.

Canine blood was visually inspected for hemolysis and compared with the Food and Drug Administration's standard of less than 1% hemolysis as measured by plasma-free hemoglobin. This was the basis for deciding to transfuse or dispose of stored canine blood. Free hemoglobin was measured in stored red blood cell units and compared to a calculated 1% hemolysis. Veterinarians and technicians determined if they would transfuse units based on visual inspection for hemolysis. Their evaluation was compared to the calculated hemolysis cutoff. The evaluations of veterinarians and technicians were significantly different from the mathematically derived cutoff. The technicians' visual assessments of the usability of samples were significantly different from those of the veterinarians: technicians more frequently judged the sample as unusable. Experienced veterinary personnel both over- and under-estimate the degree of hemolysis in stored canine RBCs. We recommend objective analysis of the amount of free hemoglobin in stored blood prior to transfusion.