Is Verification Unnecessary if Validation is Performed?

As stated numerous times before, validation is demonstrating that products of the designed quality can be manufactured in the future, while verification is confirming that products of the designed quality have been manufactured.

According to ISO 9000:2015 definitions, verification is defined as “confirmation, through the provision of objective evidence, that specified requirements have been fulfilled,” and validation is defined as “confirmation, through the provision of objective evidence, that the requirements for a specific intended use or application have been fulfilled.”

In other words, validation ensures that a manufacturing process has the capability to consistently produce the intended result over time, while verification confirms that individual manufactured products conform to specifications. Simply put, validation is a future-oriented activity, and verification is a retrospective confirmation activity.

The Necessity of Process Validation

In the case of medical devices, process validation is primarily required for special processes.

A special process is one whose resulting output cannot be verified by subsequent monitoring or measurement. ISO 13485:2016 defines it as “a process for which the resulting output cannot be verified by subsequent monitoring or measurement, and consequently, deficiencies become apparent only after the product is in use or the service has been delivered.” Typically, processes involving destructive testing fall into this category. When a product is destroyed, it cannot be shipped, which inevitably leads to sampling (lot) inspection. In other words, since 100% verification after manufacturing cannot be performed, the process must be validated in advance to demonstrate that it can consistently achieve the intended result.

Representative examples of special processes include the following:

Process Type	Characteristics	Reason Validation is Required
Sterilization Process	Sterility can only be confirmed through destructive testing	100% sterility confirmation is impossible
Welding/Brazing	Internal joint condition requires destructive testing	Non-destructive inspection cannot guarantee integrity
Soldering	Mechanical and electrical characteristics of joints	100% destructive testing is impossible
Crimping/Press-Fitting	Internal fastening force and joint condition	Complete non-destructive evaluation is difficult
Adhesive Bonding	Adhesive strength and bonding surface condition	Can only be evaluated through destructive testing
Aseptic Processing	Maintaining sterility during the process	Real-time 100% confirmation is impossible
Assembly in Clean Environment	Control of particulate and microbial contamination	Non-destructive confirmation of internal product contamination is difficult

Why Verification is Still Necessary After Validation

I am often asked whether verification is unnecessary once a process has been validated. The answer is clearly “no.”

Process validation aims to provide a high level of assurance that products manufactured by the process will remain within product specifications. A properly validated process has been proven to have the capability to consistently achieve the intended result.

However, even when manufacturing with a validated process, various factors may cause products to deviate from specifications, including:

1. Equipment and Facility-Related Factors

• Sudden equipment failures or functional degradation
• Performance changes due to equipment aging and deterioration
• Decreased measurement accuracy due to inadequate calibration or maintenance
• Unexpected fluctuations in environmental conditions (temperature, humidity, cleanliness, etc.)

2. Human Factors

• Routine human errors (operational mistakes, incorrect settings, etc.)
• Process deviations due to assumptions or misunderstandings
• Variations in operator skill levels
• Incorrect work execution due to communication errors

3. Material and Component-Related Factors

• Variability in raw material or component quality
• Changes in manufacturing conditions at suppliers
• Material degradation due to inappropriate storage conditions

For these reasons, while process validation serves as the “foundation for continuous product quality assurance,” it is not a “substitute for quality confirmation of individual products.”

Appropriate Combination of Validation and Verification

Therefore, even for validated processes, it is essential to implement verification at appropriate frequencies and using appropriate methods during final inspection and other stages. Validation and verification have a complementary relationship, and combining both appropriately enables comprehensive quality assurance of medical devices.

Specific examples of verification methods are shown below:

Special Process	Validation	Verification (Sampling Inspection)
Sterilization Process	Sterilization validation (physical and microbiological indicators)	Sterility test, bioburden measurement, sterilization indicator confirmation
Package Sealing Process	Seal process validation (temperature, pressure, time)	Seal burst test (rupture strength test), dye penetration test
Welding Process	Welding condition validation	Tensile test, bend test, non-destructive inspection (where possible)
Soldering Process	Soldering profile validation	Tensile strength test, visual inspection, X-ray inspection
Aseptic Processing	Media fill test	Environmental monitoring, verification of process control parameters

Regulatory Requirements Perspective

This approach is also consistent with guidance from regulatory authorities in various countries.

The FDA (U.S. Food and Drug Administration) “Process Validation: General Principles and Practices (January 2011)” divides process validation into three stages as a lifecycle approach:

• Stage 1: Process Design
• Stage 2: Process Qualification
• Stage 3: Continued Process Verification

Within this framework, Stage 3 Continued Process Verification requires ongoing monitoring and data collection to continuously confirm that the process remains in a state of control. This indicates that continuous verification activities are necessary even after validation.

ISO 13485:2016 also requires, in Section 7.5.6 “Specific requirements for process validation” and Section 7.5.9 “Traceability,” appropriate record-keeping and continuous monitoring even for validated processes.

The EU MDR (Medical Device Regulation) 2017/745 Annex IX (Technical Documentation on Quality Management System Assessment and Surveillance) also requires both manufacturing process validation and continuous product conformity confirmation.

Conclusion

Process validation and verification are not a matter of choosing one or the other; both must be appropriately implemented to assure the quality of medical devices. Validation demonstrates “process capability,” while verification confirms “individual product conformity.” Building an integrated quality assurance system that incorporates both is an essential requirement for ensuring patient safety and meeting regulatory requirements.