Analytical Error & Quality Control Flashcards
What is a reference range?
Expected ‘normal’ concentration range for an analyte in a population
What are alert limits?
Results that fall out of the reference range
What are critical alert limits?
Abnormal results fall in the critical result range - requires notification to the requesting physician
What is an emergency request?
Samples that must be tested urgently - paracetamol/salicylate overdose, lactate (in sepsis), ammonia (unstable), Resus, A&E patients
How to generate a reference range?
•>120 patient samples tested - larger sample sizes help establish stable upper & lower reference limits
•Reference intervals for some analytes determined by consensus of medical experts - glucose, cholesterol
•established via parametric & non-parametric methods
Name some Pre-Analytical Errors
> Incorrect Sample to request form
Poor blood sampling technique can lead to haemolysed samples
Prolonged stasis during venepuncture can lead to samples clotting
Insufficient specimen for test required
Insufficient or excess sample to anticoagulant
Errors in Timing e.g. Cortisol
Incorrect specimen container
Inappropriate sampling site
Incorrect specimen storage
Delay in sample entering the laboratory
Name some Analytical Errors
> During testing there are multiple reasons why an analytical error can occur:
Quality control failure
Improperly trained staff performing the task
Deviations from the Standard operating procedure (SOP)
Poor quality of reagents used
Equipment malfunction
Instrument not calibrated
Name some Post-Analytical Errors?
> Delay in results being sent to the requesting clinician
Critical results not acted on
Results sent to the wrong location/doctor
Results not released from the instrument
Results lost due to an IT issue
Transcription errors
Breakdown of Analytical errors
Pre-Analytical 46-68.2%
Analytical 7-13.3%
Post-Analytical 18.5-47%
Explain controls
> Made up of patient like material e.g. human serum, urine, CSF
Same analytes as being tested
Levy-Jennings Chart used for quality control
Explain controls
> Made up of patient like material e.g. human serum, urine, CSF
Same analytes as being tested
Levy-Jennings Chart used for quality control
Data plotted to give a visualisation if a lab is working well or not
What are Westgard Rules ?
> Define specific performance limits for a particular assay - detect random & systemic errors
Various notations are assigned to QC data to determine if patient results can be released
Highlight certain issues - QC data out of control
What is CORU’s standard of proficiency domain; autonomy & accountability
