Comparison of Three Feline Crossmatch Methods—Tube, Gel Column, and Immunochromatographic Strip

Background

A pre-transfusion blood crossmatch is recommended to ensure RBC compatibility for previously transfused and transfusion-naïve cats.

Objectives

To compare 3 crossmatch methods and anti-feline globulin (AFG) enhancement for determining RBC compatibility.

Methods

Prospective study. Major crossmatches were performed using serum from 68 “recipient” cats and RBCs from 44 “donor” cats. Crossmatch methods evaluated include laboratory tube and gel column without and with AFG enhancement and an in-clinic AFG-enhanced immunochromatographic strip.

Results

Tube and gel crossmatches were performed for 211 and strip crossmatches for 133 recipient-donor pairs. RBC incompatibilities were noted in at least 1 crossmatch method for 123 recipient-donor pairs. For determination of the degree of incompatibility, there was a correlation between standard and AFG-enhanced crossmatches for both tube and gel (p < 0.001), standard tube and gel (p = 0.002), and AFG-enhanced tube and gel (p < 0.001). Twelve of 46 and 22 of 113 recipient-donor pairs deemed incompatible with tube and gel, respectively, had RBC agglutination noted only with the addition of AFG. RBC incompatibilities were noted on 15 strips, 4 of which were type A-B mismatched. Odds of detecting RBC incompatibility using strip were 2.9 (p = 0.001) and 6.1 (p < 0.001) times greater with each unit increase in the degree of incompatibility detected by standard and AFG-enhanced tube, respectively.

Conclusions

The clinical relevance of any observed RBC incompatibilities, other than known A-B mismatches, is unknown. While the strip crossmatch is simple to perform and interpret, it might not be sufficiently sensitive to detect weaker RBC incompatibilities.