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What This Guide Helps With
Troubleshoots probe, pipetting, and aspiration errors caused by sample condition, positioning, consumables, obstruction, contamination, or fluid-supply problems.
Step-by-Step Troubleshooting
1. Protect Patient Testing and Stop Repeated Aspiration Attempts
Do not continue patient testing when reliable sample or reagent aspiration cannot be assured.
Identify:
- Sample or reagent involved
- Probe or module identified by the analyzer
- Whether the fault is isolated or repeated
- Whether an unusual sound or collision occurred
If there is evidence of a probe collision, bent component, spill, or fluid leak, stop operation and remove the affected module from service.
Expected outcome: Testing is safely paused and the exact aspiration-related condition is identified.
2. Inspect the Sample or Reagent Container
Check for:
- Insufficient accessible volume
- Incorrect tube or container placement
- Excessive foam
- Visible bubbles
- Clot or particulate material
- Damaged container
- Improper cap removal where applicable to the approved workflow
Expected outcome: The fluid being aspirated is physically suitable for normal analyzer access.
3. Verify Rack and Container Seating
Confirm:
- Tube is fully seated
- Carrier is correctly positioned
- Container height and placement are consistent with the approved workflow
- Nothing is interfering with the normal sampling path
Use a known-good carrier when appropriate.
Expected outcome: The probe has an unobstructed path to a correctly positioned container.
4. Inspect Accessible Probe Areas
With the analyzer safely stopped according to normal procedures, visually inspect accessible probe areas for:
- Visible residue
- Dried material
- Obvious contamination
- Signs of contact with a tube or rack
- Apparent bending or damage
Do not manually straighten, realign, or disassemble a damaged probe unless specifically authorized and trained under approved service procedures.
Expected outcome: No obvious external damage or contamination is present. Visible damage requires removal from service and escalation.
5. Check Wash and System Fluid Conditions
Verify externally accessible:
- Wash solution availability
- System fluid availability
- Waste capacity
- Tubing or containers accessible to normal service inspection
- Any active fluidics alarms
Correct only approved external conditions.
Expected outcome: Required external fluid supplies and waste pathways are available.
6. Determine Whether the Problem Follows One Sample
When appropriate, compare the affected specimen with a verified test sample or laboratory-approved known-good specimen presentation.
If only one specimen repeatedly fails, have laboratory personnel evaluate:
- Clotting
- Viscosity
- Foam
- Volume
- Container suitability
Expected outcome: Sample-specific conditions are separated from analyzer-wide aspiration problems.
7. Verify Operation After Correcting the External Cause
After correcting a legitimate external problem, run the analyzer's normal approved workflow.
Observe for:
- Smooth probe movement
- Successful aspiration
- No repeat collision or aspiration message
- Normal sample progression
Expected outcome: Aspiration completes without repeat errors. If normal operation is restored, proceed to final verification.
8. Perform Final Functional Verification
Confirm:
- No active aspiration alarms
- Sample handling is normal
- No leakage is present
- Required calibration or QC is completed if the event could affect analytical performance
Expected outcome: Reliable pipetting and aspiration are demonstrated and laboratory acceptance requirements are met. Troubleshooting is complete.
9. Escalate Repeated or Mechanical Errors
Stop troubleshooting if:
- A probe appears bent or damaged
- A collision repeats
- Aspiration failures occur with known-good samples
- Fluid leakage is present
- Multiple unrelated specimens fail
- Normal external supplies are verified but the error remains
Expected outcome: Potential internal mechanical or fluidic problems are escalated before further damage or unreliable testing occurs.
If the Problem Persists
Common sample, container, rack, fluid-supply, and accessible contamination causes have been ruled out. The remaining condition may involve internal probe alignment, pumps, valves, pressure sensing, motion systems, tubing, control electronics, or service-level calibration.
The analyzer or affected module should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or qualified service evaluation
- Evaluated using Roche-approved documentation and approved test equipment
- Repaired or calibrated only by qualified personnel
Required functional, calibration, and QC verification must be completed before patient testing resumes.
Knowing when to stop external troubleshooting and escalate is proper troubleshooting.
Clinical Use Tip
A probe collision or repeated aspiration fault can threaten both analyzer hardware and result integrity; do not keep rerunning specimens to see if it clears.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Laboratory staff reported repeated aspiration errors when the cobas pro attempted to process specimens from one rack."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found one sample tube was not fully seated and was positioned abnormally in the rack."
Resolution
What action was taken.
Example:
"Corrected the tube position, inspected the accessible probe area for damage, verified normal aspiration, and confirmed acceptable laboratory QC before return to service."
Helpful Details to Include (If Known)
- Exact aspiration or probe message
- Sample, reagent, or module involved
- Tube or container condition
- Rack seating
- Sample volume
- Bubbles, foam, clot, or debris
- Probe appearance
- Collision or unusual sound
- Wash and waste status
- Whether known-good samples run normally
- Leakage observed
- Verification and QC results
- Final analyzer status
Final Thought
Aspiration faults require protection of both patient results and the analyzer's sampling mechanism. Check samples, positioning, supplies, and visible conditions first, then stop before internal mechanical repair when reliable aspiration cannot be restored.
That is successful troubleshooting.