Obtaining a Catheter Specimen of Urine
This article, the second in a six-part series on specimen collection, details how to collect a catheter specimen of urine.
Dan Higgins, RGN, ENB 100, ENB 998, is senior charge nurse in critical care, University Hospital Birmingham.
In all aspects of specimen collection the process must be one that reduces health and safety risk to all groups of staff handling the sample and one that reduces the risk of erroneous data/results. The first part of the series on obtaining a midstream specimen of urine outlined good practice principles for specimen collection.
Urine is a body fluid frequently collected for microbiological and/or biochemical investigation. Urine specimens may be required from patients with an indwelling urinary catheter in situ.
This group of patients in particular appears to be at high risk of developing a urinary tract infection. As a result, nurses should always be aware of the associated risks of urinary tract infection as a result of catheterisation or indwelling catheters. They need to ensure that practice around the insertion of an indwelling catheter and care of the patient is based on the best available evidence.
National evidence-based guidelines for preventing healthcare-associated infections in England were commissioned by the Department of Health and developed by a nurse-led multiprofessional team (Pratt et al, 2007).
The guidelines point out that the risk of infection appears to increase with the duration of catheterisation. In fact, catheter associated urinary tract infection (CAUTI) is the most common nosocomial infection in hospitals (Pratt et al, 2007).
Maintaining a sterile, closed urinary drainage system is central to the prevention of CAUTIs. Nurses need to be aware that any breaches in the closed system, such as emptying of the urinary drainage bag or taking a urine sample, increase the risk of catheter-related infection (Pratt et al, 2007).
Clinical indicators of urinary tract infection, pyrexia, tachycardia and changes in urine characteristics such as aroma and appearance may highlight the need for specimen collection for microbial culture and antimicrobial sensitivity.
Catheter specimens of urine (CSU) may also be required for:
Levels of particular metabolites or presence of particular drugs/drug metabolites, for example hormone metabolites and toxicology screens in the poisoned or overdosed patient;
Point of care urine analysis (urine dipsticks).
The process of obtaining a sample of urine from a patient with an indwelling urinary catheter must be obtained from a sampling port. The sample must be obtained using an aseptic technique (DH, 2003).
This port is usually situated in the drainage tubing, proximal to the collection bag which ensures the freshest sample possible. The use of drainage systems without a sampling port should be avoided (Gilbert, 2006).
Specimens should not be collected from the tap from the main collecting chamber of the catheter bag as colonisation and multiplication of bacteria within the stagnant urine or around the drainage tap may have occurred.
Aspirating urine from a sampling port has traditionally been performed using a syringe and needle. However, needle-free systems are commercially available, which may reduce the risk of inoculation injury.
The following items should be collected as preparation for collecting a catheter specimen of urine for analysis:
Syringe and needle;
Gate clip or non-traumatic clamps;
Universal specimen container;
Obtain informed consent. Provide explanations to optimise specimen quality. Ensure the procedure is performed in a way to optimise patient dignity.
Wash hands, don apron, prepare equipment. Apply alcohol handrub.
If no urine is visible in the tubing, apply a non-traumatic clamp/gate clip a few centimetres distal to the sampling port (Fig 1) (Gilbert, 2006).
Once sufficient urine has collected in the tube, wipe the sampling port with an alcohol-impregnated swab (Fig 2). Allow to dry.
Stabilising the tube below the sampling port, insert the needle into the port at an angle of 45 (Fig 3).
In a needle-free system, insert the syringe into the sampling port according to the manufacturer’s recommendations.
Aspirate the required amount of urine (refer to microbiology department to ascertain volume required) (Fig 4).
Dispose of sharps as appropriate.
‘Inject’ urine into sterile specimen pot (Fig 5).
Wipe the sampling port with an alcohol-impregnated swab, allow to dry.
Unclamp the catheter tubing as required.
Dispose of waste, remove apron, wash hands thoroughly.
Complete documentation according to organisation guidelines (Fig 6).
Dispatch the specimen to the laboratory according to organisation guidelines.
Department of Health (2003) Essential Steps to Safe, Clean Care: Urinary Catheter Care. www.dh.gov.uk
Gilbert, R. (2006) Obtaining a catheter specimen of urine. Nursing Times; 102: 19: 22-23.
Pratt R.A. et al (2007) epic2: National Evidence-Based Guidelines for Preventing Healthcare-Associated Infections in NHS Hospitals in England. Journal of Hospital Infection; 65S: S1-S64.
This procedure should be undertaken only after approved training, supervised practice and competency assessment, and carried out in accordance with local policies and protocols.