Standard Operating Procedures (SOPs) are the backbone of a medical laboratory’s quality system. They provide step-by-step guidance so tasks are performed consistently and safely. In the ISO 15189 framework, each SOP should reinforce the policies and objectives of the lab’s quality management system. By using the ISO 15189 manual as a reference, lab teams can align SOP content with required quality principles while keeping procedures practical for daily use. Writing SOPs with structure and clarity ensures consistent compliance and efficiency.

Purpose and Scope of SOPs

Each SOP should begin by stating its purpose and scope. This introduction explains why the procedure exists, when it applies, and what it achieves. Defining the scope clarifies which processes or situations the SOP covers. In an ISO 15189-aligned system, this context ties the procedure to quality objectives (for example, ensuring accurate test results or meeting safety requirements). A well-defined purpose also helps staff understand the importance of following the SOP, which supports consistent quality and safety.

Structure and Formatting

A clear, consistent structure makes SOPs easy to follow. Use a standard template. Common sections include:

• Title/ID (with version and date) for traceability.
• Purpose/Scope summarizing the SOP’s goals.
• Responsibilities defining who does what.
• Materials/Equipment listing needed items.
• Procedure Steps as a numbered sequence of actions.
• Safety/Precautions highlighting hazards.
• Records/Documentation explaining how results are recorded.
• Revision History/Approval noting authors, approvers, and dates.

Use headings and numbering consistently. Bullet lists and numbered steps make procedures clearer. Keep formatting uniform so staff focus on content. Always include the date, author, version, and next review due date on each SOP.

Language and Clarity

Use clear, concise language:

• Write simple, direct sentences in active voice (e.g. “Add 5 mL of buffer,” not passive).
• Avoid ambiguous terms; define any abbreviations or technical terms.
• Keep tense and person consistent (usually present tense, imperative tone).
• Maintain uniform terminology, units, and symbols throughout all SOPs.

Write for the intended audience. If multiple languages are used, ensure each version is accurately translated and reviewed. Clarity and precision are more important than overly formal wording. Use tables or flowcharts if they help illustrate steps more clearly.

Review and Revision Process

ISO 15189 requires controlled documents, so each SOP must have a formal review and approval process. Assign responsibility for each SOP’s maintenance (often the process owner or quality manager). Schedule regular reviews (commonly annually or when methods or equipment change). Treat updates as part of continuous improvement: feedback, audit findings, or new guidelines should trigger revisions.

• Include a revision history or log with each SOP (version number, date, author, and summary of changes).
• Approve the new version before use; mark superseded documents to prevent use of outdated procedures.
• Archive old versions and clearly label them as obsolete.
• Provide training or communication whenever an SOP is significantly revised.

Integration with the Quality System

Every SOP is part of the lab’s ISO 15189 quality management system. Effective SOPs support principles like standardization, traceability, and competency. For example, a clear SOP ensures consistent results regardless of who performs the test, providing evidence of staff competence. Documented steps and assigned responsibilities reduce errors and enhance patient safety, aligning with the lab’s commitment to accurate, reliable service.

• Cross-reference relevant sections of the ISO 15189 manual or quality policy in each SOP (e.g. risk management, document control).
• Include quality control or calibration steps if required by the lab’s quality procedures.
• Show how the procedure supports patient care or accuracy (for example, by preventing sample mix-ups or ensuring correct reporting).
• Ensure every SOP has a clear owner and is incorporated into management reviews as part of continuous improvement.

Tips for Consistency and Compliance

• Use a single SOP template across the lab for a consistent look and format.
• Number sections (e.g. 1. Purpose, 2. Scope, 3. Procedure) for easy reference.
• Keep language concise: short paragraphs, bullet points, and numbered steps.
• Include required quality checks (e.g. calibrations, control samples) and safety steps in procedures.
• Ensure only the current approved version of each SOP is accessible (archive outdated copies).
• Provide training or communication whenever SOPs are newly implemented or revised.

By following these practices, laboratories can create SOPs that are clear, user-friendly, and aligned with their ISO 15189 quality system. Well-written SOPs not only guide everyday work but also demonstrate a robust quality management system during audits, ultimately supporting accurate, reliable laboratory service.