Last Updated on September 24, 2025 by Melissa Lazaro

ISO 15189:2022 Audit – How to Prepare, What to Expect, and What Matters Most

Let’s be real—preparing for an ISO 15189:2022 audit can feel like trying to get your entire lab to run a relay race… with clipboards. I’ve helped labs of all shapes and sizes through this process, and no matter how well-prepared they thought they were, the same questions always came up:

“What are auditors really looking for?”
“Are we focusing on the right things?”
“What if someone on the team freezes during the interview?”

I get it. The audit isn’t just about your documents—it’s about whether your lab can consistently deliver reliable results under real-world conditions. And that’s what makes it nerve-wracking. But here’s what I’ve noticed: the labs that do well don’t wait until the week before to get serious. They prepare early, train their team, and focus on making their system actually work—not just look good.

In this article, I’m going to walk you through exactly what to expect during your ISO 15189:2022 audit. We’ll talk about what assessors pay attention to (spoiler: it’s more than your SOPs), how to prepare without burning out your team, and what really makes the difference between a stressful audit and a smooth one.

Whether you’re going for your first accreditation or transitioning from the 2012 version, this is the playbook I wish every lab had before the assessor walked through the door.

Let’s dive in.

Understand the ISO 15189:2022 Audit Process From Start to Finish

Before we get into prep checklists and auditor Q&A tips, let’s start with the big picture—how the audit process actually works. I’ve found that once labs understand the flow, everything else becomes less intimidating.

Here’s the typical structure for an ISO 15189:2022 audit:

1. Pre-Audit Activities (a.k.a. Stage 1 Review)

This part happens before the auditors set foot in your lab. You’ll submit documents like your quality manual, scope of services, and key procedures for review. It helps assessors get a feel for how your system is structured and whether you’re ready for the full assessment.

What to know: If there are major gaps at this point—like no risk register or missing internal audits—they might postpone or adjust your audit. So this is your first checkpoint.

2. The On-Site Assessment (Stage 2 Audit)

This is where things get real. The assessor will come to your lab, observe workflows, interview staff, and review records. It usually includes:

• Opening meeting: Quick intro, scope review, and agenda

• Facility walkthrough: From sample collection to reporting

• Interviews: With staff across departments (not just QA)

• Document review: SOPs, training logs, risk records, maintenance logs

• Closing meeting: Summary of findings and next steps

3. Audit Outcomes

At the end, the auditor will summarize any nonconformities (major or minor), observations, and positives. You’ll then receive a report outlining everything and a deadline to respond with corrective actions if needed.

4. Accreditation Decision

Once you respond to any findings and the assessors are satisfied with your corrections, the accreditation body finalizes your status.

A quick story:

I worked with a midsize diagnostic lab that went into their audit thinking it was just a document check. They were blindsided when the assessor asked a technician to walk them through a test process—and the response didn’t match the SOP. That moment led to a minor nonconformity they could’ve avoided with better prep.

Bottom line:

This isn’t just a test of your paperwork—it’s a test of your lab culture, your consistency, and your ability to link written processes with what actually happens on the ground.

What Auditors Really Look For in ISO 15189:2022

Let’s cut through the guesswork—auditors aren’t there to play “gotcha.” They’re there to assess whether your lab’s quality system is actually working, not just whether your documents look pretty.

So, what are they really paying attention to?

1. Are You Doing What You Say You Do?

This is audit rule number one. If your SOP says you review equipment logs weekly, but the last log was from two months ago? That’s a red flag.

What they want: Alignment between your written procedures and day-to-day operations.

2. Is Risk-Based Thinking Actually Embedded in Your Lab?

ISO 15189:2022 places a huge emphasis on proactive risk management. Auditors want to see that you’ve identified potential issues, put controls in place, and are actively reviewing them.

What to show: Your risk register, mitigation plans, and how risks are discussed in team meetings or management reviews.

3. Are Your Staff Competent and Clear on Their Roles?

Auditors will talk to people across your lab—not just managers. They’ll ask how staff are trained, assessed, and how competence is maintained over time.

What to prepare: Training records, ongoing assessments, and a clear competence matrix that maps tasks to qualifications.

4. Are You Reviewing Performance and Improving?

Auditors don’t just want to see that you catch problems—they want to see what you do about them. That includes internal audits, nonconformity reports, management reviews, and documented improvement actions.

What to highlight: Internal audit reports, CAPAs, meeting minutes, and examples of lessons learned.

5. Can You Prove Your Quality System Is Working?

This is where it all comes together. Your documentation, records, staff responses, and audit trail should collectively show that your system isn’t just “implemented”—it’s functioning.

Real-world lesson:

I once helped a client who had beautiful SOPs and training checklists—but they hadn’t held a management review in over a year. The assessor picked up on that immediately. We managed to turn it around by showing informal improvement meetings, but it was a close call. Bottom line? Even routine requirements like reviews really matter.

Quick Tip:

If your SOPs, records, and team behavior all tell the same story—you’re in great shape. If they contradict each other, expect questions.

Pre-Audit Preparation: What to Do 30, 15, and 7 Days Before

If there’s one thing I’ve seen make or break an ISO 15189 audit, it’s preparation. Not just having documents in place—but making sure your team is ready, your system is tight, and your records are easy to find.

The good news? You don’t need to do it all at once. A phased approach works better—and keeps everyone sane.

30 Days Before: Set the Foundation

• Run a gap-focused internal audit.
  Check that all ISO 15189:2022 clauses are addressed and that previous nonconformities (if any) have been resolved and documented.

• Review your quality objectives and recent management review.
  Make sure these aren’t just on paper—have clear evidence of follow-through.

• Update your document control list.
  Every policy, SOP, and form should be the current version—and properly approved.

• Assign roles for audit day.
  Decide who will guide the assessor, who can answer which types of questions, and who’s responsible for pulling records if requested.

15 Days Before: Rehearse and Refine

• Conduct a mock audit or “walkthrough.”
  Have someone role-play as the auditor. Pick five random ISO clauses and ask staff to demonstrate or explain how they comply.

• Check staff readiness.
  Make sure key personnel understand the procedures they’re responsible for. If they’re unsure, do short refreshers now—before they’re caught off guard.

• Update your “Top 10 Documents” file.
  Include your quality manual, audit reports, training logs, risk register, SOP samples, and management review notes. This saves time under pressure.

7 Days Before: Final Touches

• Test document retrieval.
  Open your file structure and pretend an auditor just asked for three documents. Can you find them in under two minutes? If not, reorganize.

• Clean and prep your facility.
  It’s not about perfection—it’s about professionalism. Fix broken signs, remove outdated forms from workstations, and tidy up storage areas.

• Calm the nerves.
  Talk to your team. Remind them that auditors are looking for a functioning system, not perfection. Encourage honesty and confidence.

From the field:

One small lab I worked with held 15-minute “audit warmups” for a week leading up to their visit. One tech spotted that their training file was incomplete. We fixed it before the audit—and that one catch likely prevented a finding.

Quick Tip:

The audit starts the moment the assessor walks in. How organized and confident you are from the start sets the tone for the whole visit.

How to Handle Interviews, Walkthroughs, and Questions During the Audit

Let’s be honest—this is the part that makes most teams nervous. But here’s the truth: auditors aren’t trying to trip you up. They’re trying to see if your lab does what it says it does—and if your staff actually understand the system they’re a part of.

When you shift your mindset from “test day” to “show and tell,” the whole experience gets a lot less stressful.

1. During Interviews: Keep It Honest and Focused

• If you don’t know the answer, don’t fake it.
  It’s perfectly okay to say, “Let me check that,” or “I’ll show you where that’s documented.” That shows maturity and transparency.

• Encourage staff to speak from their experience.
  Auditors want to hear how things actually work—not just memorized ISO terms.

• Use real examples when possible.
  If asked about handling nonconformities, talk through a recent one and what actions were taken.

2. During Walkthroughs: Demonstrate Control and Awareness

• Keep critical documents nearby.
  If your lab has forms or flowcharts posted at workstations, make sure they’re up to date—and that staff know how to use them.

• Label storage, chemicals, and sample areas clearly.
  A well-labeled lab signals organization and attention to detail without saying a word.

• Explain your process as you go.
  Walking an auditor through a task? Narrate what’s happening: “This is where we log incoming samples. If a label is missing, we follow SOP-14…”

3. When Questions Come Up: Show, Don’t Just Tell

Auditors love traceability. If you’re asked how you verify staff competence or maintain equipment, don’t just explain it—show them the training file or maintenance record.

Pro move: Keep a tablet or quick-access folder ready so you can pull up digital records in seconds.

Real-life story:

In one audit I supported, a staff member was asked about environmental monitoring. Instead of describing the procedure, she walked the assessor straight to the records binder and said, “Here’s last month’s trend report—we review it weekly in our team huddles.” That moment sealed the assessor’s confidence in their system.

Quick Tip:

Before audit day, run a 10-minute Q&A drill with your team. Ask:

• “What would you do if a sample label is missing?”

• “Where’s the training log kept?”

• “What’s your role in quality improvement?”

If staff can answer clearly and show evidence, you’re ready.

Nonconformities: What They Mean and How to Respond

No matter how well your audit is going, hearing the word “nonconformity” can make your heart skip a beat. But here’s the truth: most labs receive at least one finding, especially during a transition to ISO 15189:2022. It’s not the end of the world—it’s how you respond that really counts.

Understanding the Two Types of Nonconformities

1. Minor Nonconformity

This means something is missing or incomplete—but it hasn’t seriously impacted quality or patient safety.

Example: A training record is missing for one staff member, or an SOP hasn’t been reviewed in over a year.

2. Major Nonconformity

This indicates a bigger issue—something that could affect test results, compromise impartiality, or show a breakdown in your quality system.

Example: No risk assessment in place, or test results being released without proper review.

What to Do When You Receive One

Step 1: Stay calm and listen.
Take notes during the closing meeting. Ask for clarification if needed, but don’t argue. Auditors are there to report what they find—not to debate it with you.

Step 2: Review the finding internally.
Gather your team and review the issue. Is it a one-time slip? A recurring pattern? A sign that a system needs fixing?

Step 3: Submit a strong corrective action plan.
This is where a lot of labs stumble. A solid response should include:

• Root cause analysis (What led to the issue?)

• Immediate action (What did you do to contain it?)

• Corrective action (What did you change to prevent it from happening again?)

• Follow-up verification (How will you know it’s working?)

Step 4: Keep documentation clean and clear.
Your corrective action and supporting evidence should be well organized—auditors will review it before final approval.

A story from the field:

One lab I supported received a minor nonconformity for not documenting risk reviews during equipment changeovers. Instead of getting defensive, they immediately scheduled a team training, updated their SOP, and added a quick risk-check step into their change control form. The response was so solid, the assessor commended their improvement mindset in the final report.

Quick Tip:

When you respond to a nonconformity, avoid vague language like “we’ll monitor” or “staff will be reminded.” Be specific. Assign responsibility. Set deadlines. Show you’re serious.

What Happens After the Audit (and How to Stay Ready All Year)

So, the audit’s over. The assessor has packed up, the closing meeting is done, and your team finally exhales. Now what?

This is where most labs either lose momentum—or lock in long-term success.

Because ISO 15189:2022 isn’t about passing an audit once. It’s about building a system that stays sharp all year.

1. Review the Audit Report Carefully

Once you receive the official report, go through it with your leadership team and quality rep. Make sure you clearly understand:

• The findings (if any)

• The deadlines for your response

• Any opportunities for improvement that weren’t formal findings (these often become future issues if ignored)

2. Submit Your Corrective Actions (If Required)

If you received any nonconformities, your response will determine how quickly you get accredited—or re-accredited. Respond early, and make sure your actions are documented, assigned, and verifiable.

Pro tip: Keep copies of all correspondence with your accreditation body—it becomes part of your audit trail.

3. Debrief With Your Team

Even if the audit went great, schedule a debrief meeting. Talk openly about:

• What went well

• Where people felt unprepared

• Any surprises from the assessor

• Ideas to make the next audit even smoother

This keeps the whole team engaged in the quality journey—not just the QA lead.

4. Build “Everyday Readiness” Into Your Lab Culture

Here’s the biggest shift I’ve seen in successful labs: they stop treating audits like one-off events. Instead, they build habits that keep them ready all year.

Try this:

• Run quarterly micro-audits on rotating areas

• Review your risk register and objectives at team meetings

• Add a document review reminder to your calendar every 90 days

• Keep your “Top 10 Audit Docs” folder updated—even when no audit is scheduled

One client’s approach:

A medium-sized lab I worked with created a standing 20-minute “quality moment” during their monthly team meetings. Each month, a different staff member shares a document, a risk, or a process improvement. It’s simple, it keeps quality visible, and it’s made their last two audits feel routine—not rushed.

Quick Tip:

Treat post-audit time like a launchpad—not a cool-down. This is when your team is most engaged, your gaps are most visible, and your momentum is strongest. Use it.

Pro Tips & Insider Insights: How to Stay Sharp Before, During, and After the Audit

These are real-world tactics I’ve used (and seen work) across dozens of ISO 15189 audits. They’re not theory—they’re field-tested, quick to apply, and designed to help your lab stay calm, confident, and audit-ready.

Pro Tip 1: Time Your Document Retrievals

During prep, set a timer. Ask a colleague to name a clause or requirement, then see how fast you can pull up the related SOP, record, or form. If it takes more than two minutes, reorganize your folders or update your naming conventions.

Pro Tip 2: Teach Staff to Say “Let Me Show You”

Not everyone will remember exact wording from your SOPs—and that’s okay. Instead of guessing, train your team to say,
“Let me show you the procedure we follow for that.”
Walking an assessor to the answer is a sign of confidence and clarity—not weakness.

Pro Tip 3: Keep a Quick-Access Audit Folder Ready to Go

Put your “Top 10” most requested documents in one place:

• Quality policy

• Scope of accreditation

• Internal audit reports

• Management review minutes

• Risk register

• Training matrix

• Equipment calibration logs

• Complaint log

• CAPA tracker

• Organization chart

Keep it digital and searchable—or have a printed binder if your lab still runs on paper.

Pro Tip 4: Use a Risk Register Summary Sheet During the Audit

Assessors love seeing that you think ahead. A one-page summary showing your top five lab risks, controls in place, and when each was last reviewed? That’s gold.

Pro Tip 5: Debrief the Same Day the Audit Ends

Don’t wait a week. While everything is still fresh, sit down with your team and ask:

• What caught us off guard?

• What went smoothly?

• What can we improve before the next visit?

Capture those answers and turn them into real actions.

Common Mistakes and FAQs: What Trips Labs Up (and What You Should Know)

Even well-prepared labs get caught off guard by things they didn’t think mattered—or didn’t know were part of the audit. After supporting countless teams through ISO 15189 audits, I can tell you this: most audit issues aren’t about technical errors—they’re about small, avoidable gaps.

Let’s walk through the most common mistakes, and then I’ll answer a few of the questions I hear most often.

Common Mistakes to Avoid

Mistake 1: Only the QA Person Prepares for the Audit
Your quality manager can’t be everywhere at once. If the rest of the team isn’t involved, gaps will show up fast—especially when auditors start asking frontline staff questions.

Mistake 2: SOPs Say One Thing, Practice Shows Another
If what your staff say during interviews doesn’t match what’s written in your procedures, that’s a credibility problem. Align your training, your documents, and your daily practice.

Mistake 3: Unresolved Internal Audit Findings
If you ran an internal audit two months ago but didn’t close out the nonconformities? The assessor will ask why—and expect evidence of action.

Mistake 4: Records Are “Somewhere… Probably”
You know the one. It’s that staff member who says, “Oh yeah, I think that form’s in the drawer.” Disorganized or scattered records can lead to avoidable findings.

Frequently Asked Questions

Q1: How long does the ISO 15189 audit usually take?
It depends on your lab’s size and complexity, but most full assessments take 2 to 5 days. You’ll receive a detailed audit plan and schedule ahead of time.

Q2: What happens if we get a nonconformity?
You’ll need to submit a corrective action plan within a set timeframe—usually 30 days. Most minor findings are fixable and don’t delay accreditation if your response is clear and prompt.

Q3: Can assessors talk to any staff member during the audit?
Yes—and they will. That includes lab techs, admin staff, and even sample collectors. Everyone should be briefed on their role and comfortable explaining how they do their work.

Q4: Can we fail the audit?
You won’t “fail” in the traditional sense unless major nonconformities go unaddressed or there’s a complete system breakdown. Most labs pass with minor findings—and grow stronger from the process.

Be Prepared, Stay Calm, and Let Your System Speak for Itself

Here’s what I’ve learned from years of supporting labs through ISO 15189 audits:
It’s not about being perfect—it’s about being prepared.

Auditors don’t expect your lab to run without a single flaw. What they want to see is a system that works, a team that understands their role, and a culture that’s serious about quality, safety, and patient outcomes.

Let’s quickly recap what matters most:

• Know the process. Understand the audit flow—from document review to closing meeting.

• Prep early. Start 30 days out, and build a system your team can actually use—not just one that looks good on paper.

• Focus on evidence. Show what you do, don’t just talk about it.

• Train your team. Auditors will talk to more than your QA lead—make sure staff are confident and ready.

• Respond with purpose. If you get a nonconformity, take it seriously. A strong response builds trust.

In my experience, the most successful labs aren’t the ones with the most polished SOPs—they’re the ones where the system feels real. Where quality isn’t just a binder on the shelf. It’s in the conversations, the decisions, and the everyday habits.

Ready to feel confident going into your audit?

Start by downloading our ISO 15189:2022 Audit Prep Checklist—or book a free consult to walk through your current readiness. We’ll help you cut through the guesswork and focus on what really matters.

You’ve done the work. Now let’s make sure you’re ready to show it.