Urinary Collection Methods

Laboratory testing for urine may be performed for various reasons. From routine health checks to ruling out a disease or toxicity, urine remains an important tool for clinical diagnosis. What type of test ordered will determine the method for how the urine sample is collected.

Methods

• The random specimen of urine collection is most commonly used because it's the easiest to obtain and readily available. As the name implies, this can be collected at any time. Some inaccuracies may occur in this specimen. It may be diluted or have changes due to physical activity.

  Urine that's collected when first voiding upon awakening is called the first morning specimen. The urine is more concentrated, helping to make detection of abnormalities easier.

  Timed specimen methods for collection are classified as short-term and long-term. Short-term methods collect urine for two hours, and long-term methods can collect urine for 12 or 24 hours. The 24-hour method is extremely important as it reveals how kidneys adjust to changing physiologic needs over a long period. The kidneys excrete substances at different times of the day or night, so if one urine sample is not obtained, it will be inaccurate. The collection container contains a preservative to prevent breakdown of urinary components.

  A specimen may be collected from an indwelling catheter or by temporarily inserting a catheter through the urethra into the bladder. With an indwelling catheter there are generally no risks. Inserting a catheter may carry complications of bleeding, infection, damage to the bladder or urethra, or misplacement.

  The clean catch method, or midstream, refers to a small amount of urine being voided into the toilet. The urine stream is stopped, then a container is carefully positioned to catch the remaining urine.

  Suprapubic aspiration is performed when a bedridden patient can't be catheterized to provide a sterile specimen. In this method, a needle is inserted through the abdominal wall into the bladder to aspirate the urine.

Considerations

• Pediatric patients may not be able to void on command and may need to have a special urine collection bag. This adheres to the skin surrounding the urethral area. When the desired amount of urine is collected, it then may be transferred to an appropriate container.

  Collection of urine from a diaper is not recommended as debris may contaminate the specimen.

  Urine should be refrigerated within two hours of obtaining it, unless it's collected in a container with preservatives.

  Follow instructions from your health-care provider when obtaining specimens. Prior to collection of urine, be sure to drink plenty of fluids unless otherwise instructed. The urethral area in females must be clean and dry. Males must clean and dry the head of the penis as well, to prevent contaminants from entering the urine stream when obtaining a specimen.