Standard Operating Procedure: Urinalysis Testing

This Standard Operating Procedure (SOP) outlines the standardized process for the collection, handling, and analysis of urine specimens to ensure clinical accuracy, diagnostic reliability, and adherence to biosafety protocols. By following these rigorous guidelines, laboratory personnel minimize pre-analytical errors, maintain sample integrity, and guarantee consistent results across all testing cycles. This protocol applies to all clinical staff performing manual reagent strip testing or automated urinalysis in this facility.

Phase 1: Patient Preparation and Specimen Collection

• Verify patient identity using at least two unique identifiers (full name and date of birth).
• Provide the patient with a sterile, leak-proof specimen container.
• Instruct the patient on the "clean-catch, mid-stream" technique to minimize contamination from skin flora.
• Ensure the patient understands that the container must be labeled with their name, date, and time of collection before leaving the restroom.
• Confirm the specimen volume is sufficient (ideally 10–15 mL) for testing.

Phase 2: Specimen Handling and Inspection

• Perform hand hygiene and don appropriate Personal Protective Equipment (PPE), including gloves, fluid-resistant lab coat, and eye protection.
• Check the specimen container for leaks or improperly secured lids.
• Inspect the sample for visual characteristics: color, clarity (turbidity), and the presence of particulate matter. Document these observations in the Laboratory Information System (LIS).
• Ensure testing occurs within 2 hours of collection. If testing is delayed, ensure the specimen is refrigerated at 2–8°C (note: samples must reach room temperature before testing).

Phase 3: Analytical Procedure (Reagent Strip Method)

• Mix the specimen gently by swirling the container to resuspend any sediment.
• Remove one reagent strip from the original vial and immediately reseal the vial tightly to prevent moisture degradation.
• Briefly dip the reagent strip into the urine, ensuring all pads are fully saturated.
• Remove the strip and drag the edge against the container rim to remove excess urine, preventing "run-over" (where chemicals from one pad bleed into adjacent pads).
• Hold the strip horizontally to prevent cross-contamination of reagents.
• At the precise time interval indicated by the manufacturer, compare the color change on the pads to the color chart on the bottle label.
• Record the results immediately in the LIS, including the lot number and expiration date of the reagent strips.

Phase 4: Waste Disposal and Documentation

• Dispose of the specimen container in a designated biohazard waste receptacle.
• Dispose of the used reagent strip according to infectious waste protocols.
• Sanitize the workspace with an EPA-approved disinfectant.
• Perform a final quality control check: verify that all results are logged and that any critical values are flagged for physician notification per institutional policy.

Pro Tips & Pitfalls

• The "Run-Over" Effect: This is the most common error in manual urinalysis. Always blot the edge of the strip on absorbent paper if excess urine is present to prevent reagent contamination between pads.
• Expired Reagents: Never use strips past their expiration date or those exposed to moisture. If the desiccant in the bottle has turned color or if the strip shows discoloration before use, discard the entire lot.
• Temperature Sensitivity: Testing a cold specimen directly from the refrigerator will slow the enzymatic reactions on the pads, leading to false-negative or falsely low results. Always allow the sample to equilibrate to room temperature (approx. 20–25°C) before analysis.
• Lighting: Always perform visual comparisons under white light. Fluorescent or tinted light can skew your perception of color changes, leading to inaccurate grading of trace amounts.

Frequently Asked Questions (FAQ)

Q: What should I do if the specimen is extremely turbid or cloudy? A: Record the turbidity in the LIS. If the cloudiness interferes with visual interpretation, centrifuge the sample or consult the facility’s policy on filtration or microscopic follow-up protocols.

Q: Can I use a specimen that has been sitting at room temperature for 4 hours? A: No. After 2 hours, urine samples undergo chemical changes (such as bacterial proliferation and pH elevation) that invalidate the test results. A new specimen should be requested.

Q: Why must I recap the reagent strip vial immediately after removal? A: Reagent strips are highly sensitive to moisture and light. Exposure to ambient humidity can cause the chemical reagents to degrade prematurely, resulting in false test readings.