How should a urine sample be collected from a catheterized patient?

Urine Collection from Catheterized Patients

For patients with indwelling urinary catheters, always collect urine by aspirating from the sampling port of the catheter using aseptic technique—never collect from the drainage bag. 1

Collection Technique

Proper Sampling Method

• Aspirate urine directly from the catheter sampling port using a sterile syringe and needle (or needle-free port system if available) to minimize contamination and ensure diagnostic accuracy. 1, 2
• The sampling port method provides contamination rates of only 4.7-12%, compared to significantly higher rates with other collection methods. 2
• Never collect specimens from the drainage bag, as this leads to false-negative results in 50-64% of biofilm-positive microorganisms and introduces substantial contamination. 1

Step-by-Step Collection Process

• Clamp the catheter tubing distal to the sampling port for 10-15 minutes to allow fresh urine to accumulate (if the patient is producing adequate urine). 2
• Clean the sampling port with an antiseptic pad (typically alcohol or chlorhexidine) and allow it to dry. 2
• Insert the needle at a 45-degree angle into the sampling port and aspirate 10-20 mL of urine into a sterile syringe. 2
• Transfer the specimen immediately into a sterile collection container. 2
• Remove the clamp from the catheter tubing to restore drainage. 2

Specimen Handling

Immediate Processing Requirements

• Transport the specimen to the laboratory within 1 hour of collection to avoid bacterial multiplication. 1
• If transport will be delayed beyond 1 hour, refrigerate the specimen at 4°C immediately. 1, 2
• Process refrigerated specimens within 4 hours to maintain diagnostic accuracy. 2

Documentation

• Label the specimen as "catheterized" to inform laboratory interpretation of colony count thresholds. 2
• Document the time of collection and any delays in processing. 2

Diagnostic Interpretation for Catheterized Specimens

Colony Count Thresholds

• For catheterized specimens, colony counts of ≥10³-10⁵ CFU/mL indicate infection, which is lower than the traditional ≥10⁵ CFU/mL threshold used for clean-catch specimens. 3
• Any growth from a properly collected catheterized specimen should be interpreted in clinical context, as catheter-associated infections may present with lower bacterial counts. 3

Safety Considerations

Infection Control

• Use needle-free sampling ports when available to eliminate the risk of needlestick injuries to healthcare workers. 4
• Maintain strict aseptic technique throughout the collection process to prevent introducing new pathogens into the catheter system. 5
• Never disconnect the closed drainage system, as this dramatically increases infection risk. 5

Common Pitfalls to Avoid

• Do not collect from the drainage bag, as this produces unreliable results with high false-negative rates and contamination. 1
• Do not use bag-collected specimens to diagnose catheter-associated urinary tract infections, as they cannot distinguish true infection from colonization. 1
• Do not delay specimen processing, as bacterial counts change rapidly at room temperature, leading to inaccurate results. 1, 2
• Do not interpret catheterized specimens using the same colony count thresholds as clean-catch specimens, as lower counts may be clinically significant. 3