Open Access
Table 2
FMECA matrix of critical risks for SARS-CoV-2 detection by real-time RT-PCR.
| Stage of analytical process | Function | Failure mode | 5M | Causes | Local effect | End effect | Initial frequency | Initial severity | Initial non-detection | Initial criti-cality | Thresh-old | Measure(s) recommended | Follow-up | Person responsible for corrective measures | Residual frequency | Residual severity | Residual non-detection | Residual criticality | Thresh-old |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Extraction | Extract RNA of virion to make it detectable by RT-PCR | Extraction stage poorly executed | Manpower | Loss of sample traceability during testing process | Position of samples in testing process not known | Complete retest of several series, loss of ime and resources, high risk of deadline failure | 2 | 5 | 2 | 20 | 75 | Create “plate plans” with essential information: series number, all patients in the series, with their names, file numbers, barcodes and exact position in the corresponding extraction plate that is identified by the series number | Mention of these measures in the Method Operating Procedure | Supervisory Technician | 1 | 5 | 1 | 5 | 75 |
| Error depositing samples in extraction plate (patients switched) | Results of two patients switched | High risk of reporting an erroneous result | 4 | 5 | 5 | 100 | 75 | Follow plate plan meticulously (see above), printed out to show correct position for each patient | File the day's plate plans in a suitable filing tray | Laboratory technician | 3 | 5 | 5 | 75 | 75 | ||||
| Materials | Pre-analytical deadlines exceeded | Viral RNA is very unstable, may not be detected despite having been initially present in the sample | Risk of false negatives | 4 | 5 | 2 | 40 | 75 | Verification of pre-analytical deadlines for samples. If the pre-analytical deadline has been exceeded, it may be decided to process the sample, but it should be monitored up to validation in case the result is invalid: no retest, instead request for a new sample | Mention of these measures in the Test Operating Procedure | Laboratory technician | 4 | 3 | 1 | 12 | 75 | |||
| Poor quality sample | The virus was not isolated from the sample, whereas the patient is infected | Risk of false negatives | 4 | 4 | 5 | 80 | 75 | Training of sample-takers by biologists; provision of a clear and comprehensive sample collection manual that sample-takers can consult | Validation of an extra qualification to cover nasal-pharyngeal swabbing for the detection of SRAS-Cov2 | Biologists responsible for the Method | 3 | 4 | 5 | 60 | 75 | ||||
| Extraction stage not carried out | Machinery | Technical failure, machine blocked | Shutdown of overall process, inability to provide results for indetermi-nate period | Considerable loss of time and resources for the laboratory, unavoidable deadline failures | 1 | 5 | 1 | 5 | 75 | Implementation of back-up solution if available and validated. If not, urgent purchase of manual extraction kits with microcolumns | Use of back-up method indicated on patient files if this is the case | Biologists responsible for the Method | 1 | 4 | 1 | 4 | 75 | ||
| Mix prepa-ration | Prepare the reaction mixture containing all the reagents necessary for the reverse transcription and amplification stage | PCR mix preparation stage poorly executed | Manpower | Loss of sample traceability during testing process | Position of samples in testing process not known | Complete retest of several series, loss of time and resources, high risk of deadline failure | 2 | 5 | 2 | 20 | 75 | Create “plate plans” with essential information: all patients in the series, with their names, file numbers, barcodes and exact position in the corresponding extraction plate that is identified by the series number | Mention of these measures in the test Operating Procedure | Supervisory technician | 1 | 5 | 1 | 5 | 75 |
| Poor homogenization of mix | Risk of non-functional mix (that does not permit amplification of the target RNA fragment) | Series needs to be retested, loss of time and resources and high risk of deadline failure | 4 | 4 | 5 | 80 | 75 | Ensure traceability so as to know who prepared the mix for each series. If the series is no good because of a mix problem, find the source of the problem and harmonize practices | Creation of a shared “problems encountered” document that everyone can fill in, with a solutions column | Supervisory technician | 3 | 4 | 4 | 48 | 75 | ||||
| Strips with mix left open to the air for too long | Risk of contamina-tion of PCR wells by RNA of SRAS-Cov2 | Risk of false positives | 4 | 4 | 5 | 80 | 75 | Revise Operating Procedure for this stage to ensure mix is distributed at the last moment and strips are closed with proper caps as quickly as possible without compromising flow | UpdateTest Operating Procedure with these organizational concepts | Supervisory technician | 3 | 4 | 5 | 60 | 75 | ||||
| Poor homogenization of patient samples in the mix | Amplification reaction not possible, patient sample needs to be retested | Loss of time and resources, risk of deadline failures | 5 | 3 | 5 | 75 | 75 | Ensure traceability so as to know who prepared the mix for each series. If the series is no good because of a mix problem, find the source of the problem and harmonize practices | Creation of a shared “problems encountered” document that everyone can fill in, with a solutions column | Supervisory technician | 4 | 3 | 5 | 60 | 75 | ||||
| Error depositing samples in PCR strips: patients switched | Results of two patients switched | High risk of reporting an erroneous result | 4 | 5 | 5 | 100 | 75 | Use of 8-channel multichannel pipette to avoid pipetting patient samples one by one, thus dividing error risk by 8 | Update Test Operating Procedure with these organizational concepts | Laboratory technician | 3 | 5 | 5 | 75 | 75 | ||||
| Amplification | Amplify RNA of SRAS-Cov2 to make it detectable via the different fluoro-chromes | Amplification stage poorly executed | Method / organization | Procedure allowing manual data entry (risk of error) | Risk of error related to file number entries for exporting results to LIMS | High risk of reporting results to wrong patients | 4 | 5 | 1 | 20 | 75 | Install scanning system to avoid manual entry: barcodes for each patient scanned into device instead of file numbers being copied | Update Test Operating Procedure with these organizational concepts | Laboratory technician | 3 | 5 | 1 | 15 | 75 |
| Machinery | Technical failure, machine blocked | Shutdown of overall process, inability to provide results for indetermi-nate period | Considerable loss of time and resources for the laboratory, unavoidable deadline failures | 1 | 5 | 1 | 5 | 75 | Implementation of back-up solution if available and validated. If not, urgent purchase or hire of new thermal cyclers | Use of back-up method indicated on patient files if this is the case | Biologists responsible for the Method | 1 | 4 | 1 | 4 | 75 | |||
| Series validated whereas controls were non-compliant | Patient results may be distorted by contami-nation (false positives) or reaction failure (false negatives) | High risk of reporting an erroneous result | 2 | 5 | 3 | 30 | 75 | Create list of criteria to be verified when validating a test series | Update Test Operating Procedure with these organizational concepts and create a traceability sheet with the verification criteria to be checked off by the technician for each series | Supervisory technician | 1 | 5 | 3 | 15 | 75 | ||||
| Validation of results | Technically validate results so diagnostic reports can be sent out | Validation of results stage poorly executed | Manpower | Misinterpre-tation of curves and Ct | Risk of misinterpre-tation of results (false positives/false negatives/retests necessary) | High risk of reporting an erroneous result | 4 | 5 | 3 | 60 | 75 | Creation of a table with all results that may be encountered, with the action to take for each possibility: positive to validate, negative to validate, retest necessary or biologist's opinion needed | Update Test Operating Procedure and Workplace Information Sheets with these organizational concepts | Supervisory technician | 2 | 5 | 3 | 30 | 75 |
| Procedure allowing manual entry of results and/or file numbers (risk of human error) | Manual entry of an erroneous result on a patient file or an erroneous file number | Risk of reporting an erroneous result or sending result to wrong patient | 3 | 5 | 3 | 45 | 75 | Creation of rules of expertise for interpretation of results directly in the LIMS with raw values from thermal cyclers | IT (Information Technology) project to be validated for new configuration | Supervisory IT technician | 2 | 5 | 3 | 30 | 75 | ||||
| Method / organization | Poor management of human error risk (lack of traceability of actions carried out, too little automation, etc.) | Human errors become difficult to detect and a test result may be sent out before a potential error is found | Risk of reporting an erroneous result or sending result to wrong patient | 3 | 5 | 3 | 45 | 75 | Keep a record of entry errors in order to highlight critical flaws that need to be overcome with a view to conformity of results, and implement specific measures to reduce this risk of human error | Update Method Operating Procedure and Workplace Information Sheets with these organizational concepts | Supervisory technicians | 1 | 5 | 3 | 15 | 75 | |||
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