Pre-analytical errors: how to detect and interpret HIL interference

Errors can occur at any stage in the pre-analytical, analytical, or post-analytical stage of a diagnostic test. It is general practice for errors in the analytical stage to be identified through quality control procedures. However, pre-analytical errors are often treated with less importance than those in later stages of testing. Interference caused by haemolysis, icterus and lipaemia (HIL) are common forms of pre-analytical error which affect assay methods, yielding erroneous results. HIL interference is not novel and has been historically identified through a series of visual assessments.

While haemolytic, icteric and lipaemic interference causes a visual change in the sample, these methods are not quantitative and are subject to interpretation by laboratory professionals. Modern analysers have built-in capabilities for the automated detection of HIL interference which can quantitatively or semi-quantitatively measure haemolysis, icterus and lipaemia, and provide and an index for each. This data can then be used to determine if a sample should be accepted for testing or rejected due to intrinsic interference. 

Haemolysis