2.2 Troubleshooting Flashcards
Result does not match clinical findings- approach
Generic template of answers
Caveat
- depends on the assay in question
- critical vs routine result/clinical impact/urgency
- Investigate
- post analytical; transcription, data entry error , correct patient
- analytical; QC on the day, calibration, machine issues, other samples in the run
- pre-analytical; correct patient, primary tube - If a mistake
- short term harm vs long term
- short term; redact report, amend, phone requester to explain
- - open disclosure
- CAR/incident form
- root cause analysis
- report at lab/management meeting - Solution
- education
- training
- algorithms
- action limits - Monitor situation
External QAP result falls outside of the allowable limits- approach
- Investigate
- post analytical: transcription error/data entry
- analytical run: QC, calibration,
- previous cycles; ongoing bias or random error
- pre analytical; correct specimen, transport/handling, reconstitution - If random
- repeat - If ongoing/systemic, drift
- equipment
- lot numbers of reagents
- method group - Clinical implication
External QAP result falls outside of the allowable limits- approach
- Investigate
- post analytical: transcription error/data entry
- analytical run: QC, calibration,
- previous cycles; ongoing bias or random error
- pre analytical; correct specimen, transport/handling, reconstitution - If random
- repeat - If ongoing/systemic, drift
- equipment
- lot numbers of reagents
- method group - Clinical implication
- QAP corrective action form/monitor
What are some of the pre-analytical errors?
patient factors- preparation, medications
collection factors- poor technique, contamination, incorrect tube, hemolysis, insuff volume, inadequate labelling, incorrect test
transit factors- failure to store, separation of sample, aliquot sufficient volume, freezing/thawing, temp
General approach to troubleshoorting
- post ana, ana, pre ana
- sourcing errors general principles
- specific method/platform considerations
- random vs systematic error
- then incident form/CAR/ raise in meeting and monitor**
What are some of the pre-analytical errors?
patient factors- preparation, medications
collection factors- poor technique, contamination, incorrect tube, hemolysis, insuff volume, inadequate labelling, incorrect test
transit factors- failure to store, separation of sample, aliquot sufficient volume, freezing/thawing, temp
automated aliquots- alignment, slash, contam
** liaise with specimen collection/clinical team
What are analytical errors?
Internal QC non conformity- outside allowable limits
Calibration
Platform- automated vs manual, failure to add, bubbles/blocked tubing,maintenance, calibration, mechanical fault (systematic),
Reagent-storage, expiry, faulty batch, contam (syst(
Operator-non compliance to SOP, bias, pipetting tech if manual
What are post analytical errors?
Transcription of results- comments, data entry verified/ second reader
Release of results
Interpretation- incorrect reading (training)
General format of dealing with a non-conformity
- identify
- investigate (what, who, when, clinical significance)
- immediate corrective action
- root cause analysis
- preventative strategy
- document
- discussion/management meeting
- monitor
- NATA will review
QC random error- what are the potential causes and approach?
Random error- sudden shift in QC
- QC material itself; wrong one, degraded/expired, evaporated
- reagent lot new
- calibration issue
- instrument issue
- operator issue on the day; pipette, incubation, temperature, variation reader
First step- check QC material, can re-run
If still out, can examine reagent/instrument/operator/other QCs (first party)
If other QCs affected on the instrument likely instrument issue and may require servicing
Or may need recalibration if QC despite re-run still out
Internal QC has failed with R4s- what is your approach?
Explain R4s
Reject run, need to ix before pursuing further tests
- need info is it kit/3rd party
- what about other levels of QC?
- other QCs on the platform ok?
Random error (reagent/instrument/operator); imprecision
Re-run
New lot
Previous known patient samples could be re-run
Results from different labs do not agree- what are the potential sources of variation for this result once lab error has been excluded?
Pre-analytical;
- different labs environmental- water, temp, centrifuge
- Biological variation of the sample to the detection kit
Method
- reagent variation; calibration/ curve
- batch to batch variation
- ag source ag/substrate, capture antibody
- avidity of ab, isotype detected
- nature of method and sensitivity/specificity
post analytical
- reference range
- cut offs
- reporting units
mention gold standard methods ie CIEP for ENA
Reagent recall question, results have already gone out, what would you do? apparoch
- immediate corrective action
- ID results affected/retraction/amendment
- stop testing current samples
- freeze samples coming in
- contingency plan
- communication to users - Clarify with company/manufacturer
- issue
- other results affected
- when new lot can be sent - Contingency
- get new lot and re run all/amend results
- may have to consider sendaway to another unaffected lab
4 . CAR form
- discuss at meeting
-close when able
Kit recall, company no longer making it in 3 months- what do you do? Apprach
New method • Investigate i. New method 1. Literature 2. EQAP 3. Colleagues 4. What platform is already available ii. 3 month worth of supply- how many tests is that, plan timeframe • Deciding on a new method i. Pre analytical- sample handling/storage ii. Analytical- ease of sourcing kit/ controls, method platform , analytical performance characteristics, safety, staff expertise/experience iii. Post analytical- LIS, interpretation iv. Costs/financial implications • Validation i. Cross validation 1. Of known pos/neg samples, EQAP samples, and also of samples from patients without disease 2. Depending on platform etc a. Precision b. Correlation c. Agreement
• If new method
i. Notify NATA/QAP
ii. New SOP
iii. Scope of practice
iv. Training
v. Communication
vi. Parallel testing for some time
What are some interferences in immunoassays?
Antibody related or non antibody related
Positive/neg interference
Antibody
- anti analyte ab
- anti animal ab (esp HAMA)
- mAbs
- autoantibody
- paraprotein
- cryoglobulin
- heterophile antibody
- cross reactivity
- RF
- hook/prozone effect
Non antibody
- medications/drugs
- contrast agent
- fibrinogen/CRP in EPG
- lipemia
- hyper bilirubinemia
- hemolysis
- other sample matrix
