“Uncontrolled variation is the enemy of quality.”—W. Edwards Deming

For more than 30 years, industry has been trying to improve the quality of their products and services, and when they meet certain criteria from independent auditors, throwing terms about like ISO 9000, ISO 9001, ISO 13485, cGMP, QSR, and more.

What do all of these mean in the context of sterile processing, what can be learned from these standards, and how do they apply to the nuts and bolts of a quality system?

A few definitions

ISO 9000 is “defined as a set of international standards on quality management and quality assurance developed to help companies effectively document the quality system elements needed to maintain an efficient quality system. They are not specific to any one industry and can be applied to organizations of any size.”[1]

ISO 9001 is “the international standard that specifies requirements for a quality management system [that] organizations use…to demonstrate the ability to consistently provide products and services [emphasis added] that meet customer and regulatory requirements.”2 This was first implemented in an SPD by Richard Schule, then at Cleveland Clinic.

ISO 13485 “specifies requirements for a quality management system where an organization needs to demonstrate its ability to provide medical devices and related services that consistently meet customer and applicable regulatory requirements.”3

cGMP (current good manufacturing practices) “are the practices required in order to conform to the guidelines recommended by [the FDA] that control the authorization and licensing of the manufacture and sale of…medical devices” (and other regulated products).4

QSR (quality system regulation) establishes the need for medical device manufacturers to comply with cGMP.

ANSI/AAMI ST90:2017 Processing of Health Care Products: Quality Management Systems for Processing in Health Care Facilities applies the thought processes behind these methods of assuring quality products and services to sterile processing.

I am going to focus on the aspects of ST90 that apply to ensuring that your SPD processing equipment provides the same results, every cycle, every day.

Some questions

How do I know what I can/should expect from my washers, sonics, sterilizers, insulation testers, borescopes, etc.?

You test them against things like indicators or specific test items that are available for this purpose. But, given that there are no standards for anything but sterilization indicators, you may be testing against an easy test or a hard test. Or a test of unknown or variable quality.

But they have a 510(k) (if they do), so they have been validated by the FDA.

Anyone who has bought the proverbial Monday car (you know, the ones that were built by workers who were recovering from the weekend) knows that not all Chevrolets are created equal. Or Toyotas, or whatever. Having a 510(k) means that the data given to the FDA met the requirements that FDA imposes upon that device. It does not mean that the specific device in question, installed in your facility, has the same ability to perform to the requirements of a standard.

Well, what could it do when it was installed?

Manufacturer’s commissioning reports are not always shared with their customers; many times with just an “It’s good, let us fix it” being conveyed to you. But you should have these reports. It’s your device now, and you should have a performance baseline so you know what it can do and what it should be able to do if you test it again to prove that it still works as well as it did when it was handed off to you.

This information is part of the basis of a quality system as defined in AAMI ST90. And there is a structure set of procedures for doing this testing. These definitions are given below.

There’s a lot of devil in the details.

In IQ:

The safety features should be cataloged, for example:

  • Pressure vessel ratings
  • Overpressure safety valves
  • Air break filter particle size rating

The sufficiency of the utilities should be tested, for example:

  • Voltages within ±10% of the nominal voltages
  • Fusing appropriate for the current needed
  • Wiring of sufficient size to carry the needed current
  • Proper grounding
  • Water pressure
  • Water quality
  • Water flow rate
  • Water purity
  • Air pressure
  • Air flow rate
  • Steam pressure
  • Steam flow rate
  • Steam piping size
  • Steam quality and purity
  • Environmental conditions, etc.

The presence of ordered items:

  • Product identification label
  • Documentation that it was built in accord with your order, etc.

In OQ:

The ability to run the process within the requirements of the standards. Using prevacuum steam sterilization as an example:

  • Pass a Bowie-Dick test three times
  • Pass a vacuum leak test
  • Pass full- and (almost) empty-chamber load testing using commercial test packs and dunnage where needed
    • For every cycle type you will run
  • And, if you are really serious, demonstrate that the temperature profile within the chamber meets the requirements of AAMI ST8

Why the last one? To make sure that all points in the chamber can meet the sterilization conditions without going too low in temperature or too high in temperature.

In PQ:

  • Demonstrate the ability of the machine to process worst-case loads that have biological and chemical indicators (Type 5 integrators or Type 6 emulators) placed at challenge locations
    • Three times in a row; no failed indicators; no process failures
  • This is also part of product quality assurance testing for the worst-case loads

These concepts can be generalized to any instrument you obtain, from lighted magnifiers to vapor-hydrogen-peroxide sterilizers. But if you don’t do qualification testing when they are new, you will never really know if a process failure is due to the machine, the load, the operator, or the phase of the moon (it isn’t). To make sure that they keep meeting your needs, a partial requalification (some of OQ, all of PQ) should be done annually after preventive maintenance, or after a utility change or major repair, whenever that happens.

A qualified device is a trustworthy device. These procedures remove uncertainty. You have more important things to worry about.


  1. https://asq.org/quality-resources/iso-9000
  2. https://asq.org/quality-resources/iso-9001
  3. https://www.iso.org/standard/59752.html
  4. https://en.wikipedia.org/wiki/Good_manufacturing_practice