Contamination of coagulation tests with heparin from blood gas samples.

Abstract

We investigated the possibility that samples of blood could be contaminated by heparinized blood gas syringes, giving spurious results in coagulation tests. We collected coagulation test samples before (n=5) and after (n=13) blood gas sampling from a venous cannula in a volunteer. The results of activated partial thromboplastin time (APTT) tests were compared between control samples and samples taken before and after blood gas sampling. The median APTT after blood gas sampling was 71 s, significantly higher than before (median 34 s, P<0.05). We conclude that heparin from blood gas sampling syringes can contaminate coagulation tests. Heparinized samples for blood gas analysis should be obtained after coagulation test samples have been obtained.