How AAMI ST90 helps hospitals prevent recurring particulate problems
Finding a defect is important. However, finding the defect is not the same as controlling the process that created it. AAMI ST90 gives hospitals a quality-management framework for turning individual findings into documented action, verified correction, and long-term prevention.
ANSI/AAMI ST108 helps hospitals evaluate water and steam as critical inputs to medical device processing. In contrast, ST90 provides the quality-management structure needed to make the entire process more consistent, measurable, and reliable.
Together, the standards help hospitals move from defect detection to long-term prevention.
This is Part 3 of VERDA’s three-part series. Part 1 examined why visible particulate should be treated as a quality-system signal. Part 2 explored how AAMI ST108 can guide a multidisciplinary source investigation.
What AAMI ST90 adds to process control
ANSI/AAMI ST90:2017, Processing of health care products—Quality management systems for processing in health care facilities, provides a framework for managing medical device processing through documented and repeatable processes.
Its quality-management principles include:
- clearly assigned responsibilities
- documented procedures
- personnel competency
- process and equipment validation
- nonconformance management
- corrective and preventive action
- change control
- management review
- data analysis
- continual improvement
These elements become especially important when particulate, residue, staining, or other defects appear more than once.
A reported internal review connected to a hospital’s 2025–2026 instrument-processing problems concluded that safety and error prevention were not fully embedded as standard work across several units.
That observation points to a broader systems issue.
Safety cannot depend only on a technician, nurse, or manager noticing a defect at the final moment. Instead, hospitals need processes that make the correct response clear, consistent, documented, and repeatable.
A nonconformance should trigger a defined response
When staff find unexpected particulate, the hospital should have a documented process for responding.
For example, the process should answer:
- Who must receive notification?
- Who can remove trays or equipment from service?
- How should staff identify and preserve the affected item?
- Where should they document the event?
- What information should they collect?
- When does the event require a formal investigation?
- Who owns the investigation?
- How will the team identify other potentially affected loads?
- What criteria allow equipment to return to service?
Without a standard response, different teams may handle similar events in different ways.
One team may reject and document the tray. Another may simply reprocess it. A third may contact Facilities, while another may assume the particulate came from packaging.
As a result, the organization loses valuable information. It also becomes harder to identify trends, compare events, and prevent recurrence.
Corrective action is not complete until it is verified
Replacing a filter, membrane, valve, washer component, or packaging material is an action.
It is not proof that the problem has been solved.
A strong corrective-action process should document:
- the confirmed or suspected cause
- the action taken
- the responsible owner
- the completion date
- the affected equipment or processes
- required follow-up testing
- the monitoring period
- the criteria for effectiveness
- evidence that the problem did not return
Verification may include:
- follow-up water testing
- particulate analysis
- equipment inspection
- increased tray surveillance
- review of rejection rates
- comparison of results before and after the intervention
Without verification, the hospital knows that it changed something. It does not know whether the change worked.
AAMI ST90 process control depends on change management
Changes to equipment, chemicals, filters, membranes, packaging materials, detergents, or workflows can alter processing outcomes.
For that reason, hospitals should evaluate significant changes before implementation and monitor performance afterward. A structured change-control process should ask:
- What is changing?
- Why is the change needed?
- Which processes may be affected?
- What risks could the change introduce?
- What validation or qualification is required?
- Who must approve the change?
- How will staff receive training?
- What monitoring will confirm acceptable performance?
This approach helps prevent an improvement in one part of the process from creating an unexpected problem somewhere else.
Trend analysis connects isolated events
A single rejected tray may appear to be an isolated event. However, several similar events may reveal a pattern. Hospitals should compare nonconformance data by:
- date
- shift
- washer
- sterilizer
- device type
- processing location
- maintenance event
- water-quality result
- chemical change
- packaging material
For example, several particulate complaints linked to one washer may suggest an equipment issue. In contrast, similar defects across several locations may point to a broader water, steam, material, or process problem.
Trend analysis allows hospitals to see relationships that individual incident reports may not reveal.
The cost of recurring process failures
Sterile processing failures can create both direct and indirect costs.
Direct costs may include:
- repeated cleaning and sterilization
- additional labor and overtime
- instrument replacement
- equipment repairs
- laboratory testing
- engineering support
- emergency transportation
- outsourced processing
- delayed or canceled procedures
- duplicate inventory
- lost operating-room capacity
Indirect consequences may include:
- clinician frustration
- reduced trust between SPD and the OR
- schedule instability
- staff fatigue
- increased risk exposure
- reputational damage
- patient dissatisfaction
A facilities-focused review of ST108 cites an economic analysis estimating up to $1 million in first-year disruption costs for a 110-bed hospital when a steam-quality problem takes the sterile processing operation offline.
In the hospital case discussed earlier in this series, teams used 167,765 trays to support 15,359 surgeries during a seven-month period.
At that scale, quality cannot depend on memory, informal communication, or individual heroics.
It must be built into the process.
What mature process control looks like
A mature quality program will:
- recognize particulate as a process signal
- contain the immediate risk
- preserve evidence
- involve the right stakeholders
- evaluate water and steam alongside other possible sources
- analyze trends across equipment, dates, materials, and locations
- document the nonconformance
- perform root-cause analysis
- assign corrective action
- verify effectiveness
- update procedures and training
- monitor for recurrence
- review major findings with leadership
Final inspection remains important but it is one part of a larger quality system rather than the hospital’s primary defense.
Build quality into the process
AAMI ST108 reminds hospitals that water and steam are critical processing inputs that require qualification, monitoring, risk assessment, and multidisciplinary oversight.
AAMI ST90 reminds them that technical controls require an effective management system. That system depends on clear responsibilities, competent personnel, documented procedures, nonconformance management, corrective action, change control, leadership review, and continual improvement.
Ultimately, AAMI ST90 process control helps hospitals move beyond repeatedly finding defects.
It helps them control the conditions that create those defects.
Do not merely inspect quality into the final tray. Build quality into every process that produces it.