Quality in Haematology Flashcards
What are some of the preanalytical issues to consider when interpreting antibody based, chromogenic and clotting based assays?
- Antibody: presence of atypical antibodies: paraproteins, rheumatoid factor, heterophile antibodies
- Chromogenic: effects of lipaemia and haemolysis. Exogenous anticoagulant drugs.
- Clotting based assays: imprecision due to due to variation in the baseline clotting time and the levels of other factors. Presence of lupus anticoagulant or exogenous anticoagulant drugs.
List some the the pre-analytic errors that can affect outcomes of clotting based assays
• Patient problems
○ Wrong test ordered
○ Sample collected from wrong patient
• Problems with tube ○ Wrong tube ○ Under-filled tubes ○ Citrate concentration ○ Vacuum leak and citrate evaporation
• Problems with phlebotomy ○ Heparin contamination ○ Slow fill ○ Underfill ○ Vigorous shaking ○ Wrong label
• Biological effects
○ Hct ≥55 or ≤15 (changes the ratio of citrate to plasma)
○ Lipaemia, hyperbilirubinemia, haemolysis
• Laboratory errors ○ Delay in testing ○ Prolonged incubation at 37°C ○ Insufficient incubation at 37°C (cryofibrinogen) ○ Freeze/thaw deterioration
Discuss the effects of hyperlipidaemia, haemolysis and hyperbilirubinaemia
- Depending upon the spectra used, all may interfere with the results when optical based methods of clot detection are used
- Hyperlipidaemia leads to an increase in background absorbance, less reliable results obtains when optical methods used
- The spectra used for clot detection is usually outside of the wavelength of haemolysis or hyperbilirubinemia but both of these factors can lead to sample activation and therefore spurious results
List some analytical errors in coagulation testing
- Equipment malfunction
- Reagent issues (i.e. expired)
- Sample mix-ups
- Undetected failure in quality control
- Interference (endogenous/ exogenous)
List some post analytical errors that can occur in laboratory testing
- Erroneous validation of analytical data
- Failure in reporting/ communicating results
- Improper data entry/ transcription errors
- Excessive turn-around time
- Incorrect interpretation
- Inappropriate/ inadequate follow up of result
What are the commonly used commercial controls in coagulation testing?
- Freeze dried human plasma
- May be assayed (normal results provided) or unassayed (lab to determine normal range)
- Usually three controls
1) Normal
2) Abnormal (mild to moderately abnormal)
3) Abnormal (markedly abnormal) - Controls are run at least once a day
What steps should you take when QC is out of range?
• Established policies/ procedures for troubleshooting should be in place.
1) Stop issuing results/ loading new sample
2) Check all components of the test system (QC material, reagents, instrument)
3) Take corrective action
4) Once potential sources of error have been identified and corrections have been made, the control sample should be rechecked.
4) Determine the effect on already issued results
5) Retest as necessary (until a point of agreement between results is reached). The samples should be rerun along with another QC sample.
6) Correct results/ inform appropriate clinician
7) Document what has occurred
What factors can cause out of range QC results with reagents and QC agents
1) Material has deteriorated/ expired
2) Wrong lot number
3) Incorrectly prepared
4) Incorrectly/ inadequately mixed
5) Loaded incorrectly
6) Empty vial/ short sampling
What is quality?
Lab quality can be defined as accuracy, reliability and timeliness of the reported test results
What is a Quality Management System?
Coordinated activities to direct and control an organisation with regard to quality.
What pre-analytical, analytical and post-analytical factors need to be considered when developing a quality management system?
○ Pre-analytical:
- Test selection
- Patient preparation
- Sample collection
- Sample labelling
- Sample transportation
- Sample receipt and accessioning
○ Analytical
- Laboratory analysis and examination
○ Post-analytical
- Report creation
- Result interpretation
- Record keeping
- Report transportation
What are the “12 Quality System Essentials” as per the WHO?
- Organisation
- Personnel
- Equipment
- Purchasing and inventory
- Process control
- Information management
- Documents and records
- Occurrence management
- Assessment
- Process improvement
- Customer service
- Facilities and safety
What is quality control (QC)?
- Component of process control
- Monitors the processes related to the analytical phase of testing
- Allows for the detection of errors in the testing system
- QC gives the laboratory confidence that the test results are accurate and reliable before the patients results are reported.
- QC programmes help differentiate between normal variation and errors.
What are the steps for implementing a QC programme?
1) Establish policies and procedures
2) Train all staff in how to properly follow procedures and policies
3) Assign responsibility for monitoring and reviewing
4) Select a good QC material
5) Establish control ranges for the selected material
6) Develop graphs to plot control values (Levey-Jennings charts)
7) Establish a system for monitoring control values
8) Take immediate corrective action if needed
9) Maintain records of QC results and any corrective actions taken
What are controls? How and why are they used?
- Controls= substances that contain an established amount of the substance being tested- the analyte
- Tested at the same time and in the same way as patient samples
- Validate the reliability of the test system and evaluate the operators performance and environmental conditions that might impact results
