Table 1

Variance matrix of assembly critical tasks

TaskPerformance shaping factors
(SEIPS classification)
FailureExample of task variabilityProcess varianceOutcome varianceObserved controls
(SEIPS classification)
Inspect instruments for bioburdenSPD staff KSAs (person)
Tray composition (organisation)
SPD production pressure (organisation)
ITS (tools/technology)
Workstation (tools/technology)
Missed checkTray contains 50+ instruments‚ÄČand with limited space on their work surface technician inadvertently mixes inspected and uninspected instruments, failing to inspect one or more instruments.Undetected bioburdenSurgical site infection
Tray defect (bioburden)
New tray required
OR delay
Increased surgical duration
Surgical deviation
  • Remedial/specialty training (person)

  • In-service training (organisation)

  • Point-of-use observations for SPD (organisation)

SPD staff KSAs (person)
Instrument design (external)
Lighting (physical environment)
Failed inspectionTechnician inspects instrument but fails to identify bioburden hidden in instrument crevice.
Test instruments for functionalitySPD staff KSAs (person)
Tray composition (organisation)
Instrument design (external)
SPD production pressure (organisation)
Communication with point of use (organisation)
Missed checkOR did not inform SPD of issue with instrument, technician fails to test instrument as it has never been an issue previously.Broken instrument in trayPatient injury
(burn, tear, retained object, and so on)
Tray defect
(non-functioning instrument)
OR delay
Increased surgical duration
Surgical deviation
New tray
  • Remedial/specialty training (person)

  • ITS prompt (tools/technology)

  • In-service training request (organisation)

  • Point-of-use observations for SPD (organisation)

SPD staff KSAs (person)
Communication with point of use (organisation)
Instructions for use (external)
Workstation (tools/technology)
Inappropriate or ineffective checkTechnician provided with little to no knowledge of how instrument is used so test is conducted in cursory manner.
Ensure all of the correct instruments are in the traySPD staff KSAs (person)
Instrument nomenclature (organisation/external)
Instrument inventory (organisation)
Instrument storage (physical environment/organisation)
ITS design (external)
Workstation (tools/technology)
Point-of-use reprocessing (organisation)
Wrong instrument selectedThe ITS places instrument details at the end of the instrument name (eg, haemostat forceps, 14 cm, curved, satin). Technician misses appended details and chooses incorrect size and finish for the instrument.Wrong instrument added to trayTray defect
(wrong instrument)
OR delay
Increased surgical duration
Surgical deviation
New tray required
  • Remedial/specialty training (person)

  • Assign technician to point-of-use area to assist with reprocessing (organisation)

  • Standardised nomenclature (organisation)

  • Tray auditing (organisation)

  • Tray standardisation (organisation)

  • OR staff training in SPD

ITS database (organisation/external)No image, incorrect image or poor quality image in ITSImage missing in the ITS database so the technician performs an online search and chooses the instrument based on the search results.
ITS database (organisation/external)
Preference cards (organisation)
Incorrect tray specifications in ITSThe ITS database was not promptly updated according to the revised preference cards.Tray missing instrument(s)Tray defect
(wrong instrument)
OR delay
Increased surgical duration
Surgical deviation
New tray required
ITS database (organisation/external)
ITS design (external)
SPD staff KSAs (person)
SPD production pressure (organisation)
Failed to add instrument to trayTechnician counts instruments then adds them all to tray, instead of marking instruments individually in the ITS as they are added to tray, to save time.
SPD staff KSAs (person)
Instrument nomenclature (organisation/external)
Instrument inventory (organisation)
Instrument storage (physical environment/organisation)
Point-of-use reprocessing (organisation)
Layout (physical environment)
Difficulty locating instrument in assembly storage areasInstruments not returned to correct tray during point-of-use reprocessing. Technician has to identify all trays used during the case then find and check each tray for the missing instrument.Prolonged assemblyReduced throughput
ITS database (organisation/external)No image or poor quality image in ITSTechnician asks supervisor or more experienced technician to help identify the correct instrument.
Prepare tray for sterilisationSPD staff KSAs (person)
SPD production pressure (organisation)
Tray container design (external)
Failure to add count sheetTechnician rushing to add high-priority tray to the steam sterilisation load and forgets to add count sheet, indicators, locks, filters or tray labels.No count sheet in trayOR delay
Tray defect
(missing count sheet)
  • Remedial training (person)

  • Sterilisation checklist (tools/technology)

  • Dedicated workstation for sterilisation methods (physical environment)

  • Double-check procedure (organisation)

Failure to add chemical indicators to the traySterilisation not verifiableOR delay
Tray defect
(missing indicator, filter, locks or label)
New tray required
Failure to add locks to container
Failure to add filters to the containerFilters missing from tray containers
Failure to add tray labels to the containerInability to verify tray
SPD staff KSAs (person)
Sterilisation methods (external)
Tray label (organisation)
Instructions for use (external)
Layout (physical environment)
Tray placed on wrong sterilisation cartNew instrument(s) added to tray but sterilisation method not updated in the ITS. Technician prints label from the ITS and adds tray to sterilisation cart listed on the label.Wrong sterilisation methodInstrument damage
Inventory costs
Ineffective sterilisation
Surgical site infection
  • ITS, instrument tracking system; KSAs, knowledge, skills and abilities; OR, operating room; SEIPS, Systems Engineering Initiative for Patient Safety; SPD, sterile processing department.