October 23, 2019

Validation is integral part of Good Manufacturing Practices (GMPs) and covers almost every aspect of manufacturing and processing activities.  Quality Management System (QMS) software validation provides documented assurance that quality processes will consistently create products that meets pre-determined specifications and characteristics. 

Behind any successful QMS implementation is a series of steps that are critical elements of Quality Management System (QMS) validation—the Software Development Lifecycle (SDLC) and the Software Testing Lifecycle (STLC).

SDLC is a series of phases that help you develop an effective software system and manage it throughout its lifecycle. Fundamentally, SDLC allows you to turn a newly created project into one that is fully operational.  STLC doubles down on the testing phase to ensure the product is of the highest possible quality.

There are major differences between the two and you need both for a well-rounded approach to QMS validation. Let’s take a look at the differences, the points where STLC and SDLC meet and why they’re both critical for QMS validation.

Key Differences Between SDLC and STLC

While both SDLC and STLC are critical to ensuring a successful software system, there are key differences.  

STLC is the process of systematically testing software, whereas SDLC is a systematic approach to developing a software system. SDLC has a broader role in the development of software, and STLC is limited to the testing phase. Let’s break down the phases of both and take a closer look at where they differ.

SDLC: The SDLC process follows a series of phases to complete a product. It’s a critical component of software development because it ensures visibility to all stakeholders, helps mitigate potential risks and enables greater control over the scope of the project.

The phases of SDLC are:

  1. Requirements Gathering: The first and most important step of the SDLC phases is to identify the customer requirements. This phase identifies the scope of the problem and determines the solutions. The validation resource works with the customer to get all relevant information, including who the users are and the purpose of the product, and relays that information to the development team.
  2. System Analysis: The next phase requires determining the business needs, how they will be met and who is responsible for various stages of the project. This step also involves analyzing end-user needs to make sure the system is going to meet their expectations. Oftentimes, System Analysis and Requirements Gathering may be combined into a single phase to account for inter-dependencies.
  3. System Design: In this phase, all specifications are described in detail.  All essential components needed to accomplish the system’s objectives are considered at this stage.  In addition, the design phase involves developing two design plans based on requirements; high level and low level.
  4. Development: This point in the SDLC phase initiates the production process. The roadmap has been set and you know exactly what the customer and end-user need for a successful product.  Now, you can start bringing that system to life.
  5. Testing: After product development, before the software is released, it has to be validated.  At this time, the software is tested thoroughly to identify and eliminate gaps in new functionality and ensure quality objectives are being met.  Retesting is done as needed until the software meets the customer’s expectations.
  6. Deployment: After the software passes validation, it can then be delivered to the customer.
  7. Maintenance: Ongoing maintenance of the software is part of the process.

STLC: Just as software development requires a series of phases in QMS validation, STLC requires a series of activities for software testing. STLC is executed in tandem with SDLC.

The phases of STLC are:

  1. Requirements Analysis: This begins the testing lifecycle and is the basis for success. In this phase, the test team identifies the testable requirements and the quality assurance team interacts with all stakeholders.
  2. Test Planning: In this phase, the effort and costs needed for the scope of the project are determined and the test strategy is created. This stage involves identifying all roles and laying out responsibilities.
  3. Test Case Development: Here, the testing team designs test cases for execution and delivers them to quality control for evaluation. A test case is successful if it quickly identifies and solves errors.
  4. Test Environment Setup: This is a critical component of the STLC. The test environment is set up in order to replicate the user environment and the test team performs a smoke test to ensure the environment is stable enough for testing.
  5. Test Execution: In this phase, the test case is executed within the test environment to see if it passes. The test team executes tests, compares the outcome with the expected result and then analyzes those results.
  6. Test Closure: This is the final phase where the test case is analyzed, and a bug report is conducted. The testing team identifies strategies for future implementation, drawing from lessons learned in the current test cycle.

How SDLC and STLC Work in Parallel

While SDLC and STLC serve different purposes, the goal is the same—to release a high-quality, defect-free product. To achieve this, one cannot be conducted without the other. If a system is being developed and changed post-release, it must be tested to make sure it continues to do what it’s meant to do.

While testing is built into the SDLC phases, the functions performed in the STLC phase provide a more thorough approach to software testing. This makes STLC a vital component of the SDLC phase.

Why SDLC and STLC are Both Critical for QMS Validation

Software validation plays a critical role in SDLC and helps ensure that testing and development teams not only create a high-quality product but that they create the right product. It enables you to identify defects and necessary changes early on in the process, saving you time and money.

Validation is testing performed on the software that ensures it meets business and end-user requirements. It would occur at the end of the software development process to catch any errors that were missed and investigate any process deviations.

Validation testing requires an effective, systematic strategy. This is where the phases of STLC help streamline the process, by incorporating validation into the test environment set up and closure phases.

STLC is an essential part of SDLC and new software cannot be released without first passing through this phase. Like any lifecycle, the SDLC and STLC phases are fluid. Once the software undergoes changes, it must go through these processes again and re-validated.

Benefits of Having Your QMS Vendor Perform Validation

Validation is essential for ensuring the integrity of a new software system. In the Life Sciences, software that supports QMS processes must be validated in accordance with ISO 13485. The validation process itself is time intensive and challenging.  Fortunately, you don’t have to manage this yourself.

Your QMS vendor can complete custom validation services that will satisfy your regulatory and organizational requirements. Look for a company that will work with you to create a validation plan specific to your unique business needs. Your vendor should work closely with your team to come up with a strategy that reduces costs and time-to-completion.

Look for a vendor that provides traceability into every phase of SDLC and STLC to ensure thorough testing and validation coverage. SDLC and STLC testing done in tandem will eliminate gaps in functionality that could lead to warning letters and ensure that all your quality objectives are met.

The result is a cost-effective, integrated validation effort that minimizes validation of future enhancements, and allows your team to focus on other areas of the business.


Validation addresses the question, “are we building the right product the right way?” QMS validation provides traceability through every stage of the software development and software testing lifecycle to ensure complete testing and validation coverage.  While there is no one-size-fits-all approach, utilizing the services of expert validation analysts will help assure that processes work optimally with a company’s own internal software validation procedures.

AssurX Validation Management Services uses a proven methodology to validate the AssurX platform and each configured solution.  Services are customizable according to your organization’s needs. Learn more or contact AssurX for additional information.