Rethinking Investigations: Insights from a Unique Case Study

26th Sept 2025 | Matt Peplowski

 

I was once asked by a QA Approver at a client for advice on a deviation. Material handlers had entered an incorrect lot number into SAP from an incoming material shipment, and it was verified as being correct at the time. It was verified several more times through the process of quarantining, sampling, testing, and use. No one caught the issue during verification, only by chance, and right before the product went out the door. It came very close to being a recall.

 

The QA Approver said she didn’t think the root cause was ‘human error,’ but the team was pushing for that to get the deviation closed, and she was out of ideas. I asked her what the material handlers said when asked what they thought might have caused the discrepancy. She replied that she didn’t think anyone had asked them. I suggested she start there. Always involve end users in resolving deviations.

 

I asked what the workstation was like – level of activity, distractions, multi-tasking – and HOW they verify. Do they read the lot # aloud, enter it, read it back? What is everyone in the process verifying, exactly? Do they all know? Is it clear in the procedure? How were they trained?

 

How is the lot # formatted? Turns out, it was a long string of characters, not separated like a phone number, and tiny font size. She said we have no control over material vendors’ labels. She was correct, but we could ask our material handlers to physically draw a line every three digits on the packing slip to separate them into brain-friendly bits. We could also order a $40 magnifying lens from Amazon that clips to the work table so they can easily read the lot #.

 

She also suggested the team wanted to add MORE verifiers. If the first 4 or 5 didn’t catch this, adding more not only clogs up the process for the 99% of times the lot # is correct, but it dilutes the responsibility of each verifier even more.

 

The final result: Root cause was lack of clear instructions and training on how to verify, and inadequate job aids/tools to make the labels more legible; NOT human error. A contributing factor was setup of, and activity level at the computer workstation.

 

The fix: Recognizing that purchasing, implementing, and validating barcode scanners was a longer-term fix, the following were assigned as CAPA in the interim:

• Develop verification training with clear expectations on what and how to verify, including reading lot #’s aloud

• Remove downstream verifications (source documentation was not available to them anyway)

• Train materials handlers to physically break up lot #’s every three digits with lines between them for ALL applicable vendors

• Use the magnifying light

• Physically segregate the computer table where lot #’s are entered from other computers and activities, including signage to minimize distractions/interruptions

• Update all applicable procedures to reflect the changes

 

Albert Einstein said: “We can’t solve our problems using the same thinking we used when we created them.”

Human Error Prevention is not a project, procedure, or activity. It’s a mindset. If you want to be serious about preventing errors, you have to mitigate the risk factors that really cause people to make them. Retraining the handlers and other verifiers on the same information they knew, or counseling them to pay closer attention, would have solved nothing. Same with adding more verifiers.

Investigations are not a check-the-box exercise. A deviation is a free lesson to learn, an opportunity to improve. And PREVENTION is the goal and top priority of any investigation. To achieve it, we need to think differently, and go beyond ‘human error.’