Preanalytical Haemolysis in Emergency Department Samples: Rejection Rates and the Repeat Draw Nobody Counts

Abstract

Haemolysed samples are the commonest reason for specimen rejection in the emergency department, yet the repeat venepuncture
this forces is rarely tracked as an outcome in its own right. We measured haemolysis-related rejection across a twelve-month
period at three emergency departments, linked each rejection to whether a second draw was obtained and how long it took, and
examined which collection routes concentrated the problem. Haemolysis accounted for 61.4% of all preanalytical rejections
(2,014/3,281). Samples drawn through an existing intravenous cannula were rejected for haemolysis nearly three times as often as
samples drawn by direct venepuncture (9.8% vs 3.4% of draws, p<0.001), and the median time to a usable repeat sample was 47
minutes, rising to 74 minutes for patients triaged as time-critical. A targeted change in cannula-draw technique at one site cut its
haemolysis rejection rate by more than half within two quarters. Preanalytical haemolysis is not simply a laboratory quality
metric; it is a measurable source of diagnostic delay that responds to specific, identifiable changes in how samples are drawn.