User Manuals

Manuals. IFUs. They determine whether clinicians can use devices correctly, safely, and effectively. The difference between manuals that enable confident device adoption and those that confuse users reflects whether manufacturers prioritised clarity, tested with actual users, and maintained rigorous attention to regulatory requirements.

Clear writing

User manuals need to communicate complex technical information in a language your audience readily understands. Identify your intended user population and write at appropriate literacy and technical knowledge levels. Manuals for specialist physicians performing complex procedures can assume clinical knowledge and employ medical terminology. Manuals for nurses, patients, or general practitioners require simpler language to explain medical concepts clearly.

Use an active voice and imperative mood for instructions. ‘Connect the power cable to the outlet’ communicates more clearly than ‘the power cable should be connected to the outlet.’ The active voice assigns responsibility clearly, whilst the imperative mood provides direct commands that users follow easily. Next, break complex procedures into sequential, numbered steps. Each step should describe a single action users complete before proceeding. Numbered sequences enable users to track progress. Specify exact frequencies, intervals, or conditions triggering actions. Replace ‘clean the device regularly’ with ‘clean the device after every use according to procedures in Section 7.’

User manual clarity directly affects patient safety. Ambiguous instructions, incomplete warnings, or confusing procedural steps contribute to use errors, causing patient harm. Clear, user-tested manuals represent essential safety features deserving the same engineering rigour as device hardware.

_{Professor Darren Flynn. Human Factors in Healthcare. Southampton University}

Safety first

Safety warnings, contraindications, and precautions must appear prominently throughout user manuals to ensure users recognise and understand potential hazards before adverse events occur. Use standardised signal words communicating hazard severity.

Place any warnings within your instructions. Warnings that appear only in introductory sections get forgotten when users consult specific procedures. Repeat critical warnings immediately before relevant procedural steps, ensuring users see them at decision moments. Explain the consequences of ignoring warnings. Use visual symbols and icons to enhance warning recognition. Standardised ISO symbols for biological hazards, electrical risks, or temperature sensitivity communicate across language barriers whilst reinforcing text warnings. Colour coding with red for danger, orange for warning, and yellow for caution provides additional visual cues.

Ensuring accuracy

User manuals must contain complete, accurate information to enable safe, effective device use. Include comprehensive setup and preparation instructions specifying all required components, accessories, and supplies. Detail assembly procedures, calibration requirements, and verification steps confirming proper setup before first use.

Now add step-by-step operational instructions to cover all your device functions and features. Users should accomplish every intended use following the manual instructions alone. Omitting obvious steps creates errors when user assumptions about device operation differ from actual requirements. Address troubleshooting and error conditions users encounter. When devices malfunction, generate error codes, or produce unexpected results, users need guidance in identifying problems and implementing corrective actions.

Document maintenance, cleaning, and sterilisation procedures comprehensively. Specify cleaning agents, sterilisation methods, maintenance intervals, and replacement part requirements. Improper maintenance will only shorten your device's life, compromise performance, and create infection risks. Include technical specifications users need for compatibility assessment, regulatory documentation, or procurement decisions.

Maintaining regulatory compliance and accessibility

User manuals need to satisfy regulatory requirements for medical device labelling to ensure legal market access. ISO 20417 specifies medical device labelling requirements, including content, format, and symbols. IEC 62366 addresses usability engineering, ensuring instructions support safe, effective use. FDA guidance and MDR Annexe I outline US and European Union requirements, respectively.

Include all mandatory information regulators require. Device identification, including model numbers and unique device identifiers helps to enable traceability. Manufacturer contact information allows user inquiries and adverse event reporting. Intended use statements define approved applications. Contraindications, warnings, and precautions communicate safety information (proper disposal instructions help to prevent environmental contamination).
Maintain version control tracking of manual revisions. When device design changes, new safety information emerges, or user feedback identifies confusing content, update your manuals accordingly. Submit manual updates for regulatory review when changes affect safety information, intended use, or compliance with approval conditions. Use a visual hierarchy through headings, subheadings, white space, and formatting emphasis. This way, you guide the users to relevant information quickly. Dense text blocks discourage reading and hide critical information. Clear section divisions, descriptive headers, and bulleted lists improve scannability whilst highlighting key points.

Include any illustrations, diagrams, and photographs to help clarify complex procedures or device features. Visual aids communicate spatial relationships, procedural sequences, and component identification more effectively than text alone. Annotated photographs that show correct device positioning, connection points, or control locations prevent errors that text descriptions cannot eliminate.
Provide multilingual versions for international markets. Professional translation by qualified medical translators familiar with the target language medical terminology ensures accurate communication. Consider accessibility needs for users with visual, cognitive, or motor impairments through sufficient font sizes, high contrast ratios, and clear language.

Testing manuals with intended users

User testing results in safe, effective device use. Recruit representative users who match your target population in clinical speciality, experience level, and facility type. Testing only with expert users fails to identify the confusion novice users experience. Conduct task-based testing where users follow manual instructions to create more realistic device use scenarios. Observe where users hesitate, misinterpret instructions, or make errors. Note the questions your users ask and indicate any unclear content. Record completion times, error rates, and user confidence levels.

Collect user feedback through interviews, surveys, or think-aloud protocols where users verbalise their thoughts whilst following instructions. Users identify confusing terminology, insufficient detail, or misleading illustrations that developers overlook. Revise manuals addressing identified issues, then retest, confirming improvements achieved intended effects. Iterative testing and refinement continue until users can complete all tasks safely and effectively.

Instructions for use often receive inadequate attention relative to their safety importance. Effective manuals require clinical input, ensuring instructions align with actual use conditions, user testing revealing confusing content before finalisation, and iterative refinement based on post-market feedback.

_{Professor Ken Catchpole. Surgery and Perioperative Science. Cedars-Sinai Medical Centre}

The works

User manuals determine whether clinicians can use devices correctly, safely, and effectively. With a VP Med Ventures Fuel Vs Friction workshop, we can use this to guide you towards writing in a clear, accessible language appropriate for intended users and avoid any ambiguity. This way, we can maintain regulatory compliance with applicable standards, enhance accessibility through clear formatting, and provide multilingual versions where appropriate.

Waypoint checklist

What to consider when developing your user manuals and instructions for use:

• Keep the language used clear, simple, and easily understood.
• Place any safety warnings, contraindications, and precautions prominently.
• Ensure accuracy and completeness of instructions for safe and effective device use.
• Comply with relevant regulatory standards and guidelines for medical device labelling.
• Use clear formatting, illustrations, and potential multiple languages for accessibility.
• Test your user manual with your intended users.