Q When a serum separator tube is used for blood banking, what effect will the gel have on the antibody screen and x-match? Is it acceptable to use serum from a gel tube if the sample was centrifuged within 30 minutes of collection and decanted immediately following centrifugation?

A The problem with using gel tubes is that the gel forms a sticky layer between the serum and the red blood cells (RBCs). In order to obtain RBCs for testing, the technologist’s pipette must pass through this layer to sample the red cells. The gel can contaminate the RBCs during this sampling process. RBCs contaminated with the gel are “sticky” and prone to agglutinate, which can produce false-positive test results. This effect is present as soon as the specimen is spun and is not significantly affected by the amount of time the sample has spent in the tube.