In urinary catheterization a latex, polyurethane, or silicone tube known as a urinary catheter is inserted into the bladder through the urethra to allow urine to drain from the bladder for collection. It may also be used to inject liquids used for treatment or diagnosis of bladder conditions. A clinician, often a nurse, usually performs the procedure, but self-catheterization is also possible. A catheter may be in place for long periods of time (indwelling catheter) or removed after each use (intermittent catheterization).
Catheter types
Catheters come in several basic designs:<ref name=Hanno>{ { cite book |vauthors = Hanno PM, Wein AJ, Malkowicz SB |title=Clinical manual of urology. |publisher=McGraw-Hill Professional |year=2001 |page=78}}</ref> A Foley catheter (indwelling urinary catheter) is retained by means of a balloon at the tip that is inflated with sterile water. The balloons typically come in two different sizes: 5 cm3 and 30 cm3. They are commonly made in silicone rubber or natural rubber. An intermittent catheter/Robinson catheter is a flexible catheter that is removed after each use. Unlike the Foley catheter, it has no balloon on its tip and therefore cannot stay in place unaided. These can be non-coated or coated (e.g., hydrophilic coated and ready to use). A coudé catheter, including Tiemann's catheter, is designed with a curved tip that makes it easier to pass through the curvature of the prostatic urethra. A hematuria catheter is a type of Foley catheter used for Post-TURP hemostasis. This is useful following endoscopic surgical procedures, or in the case of gross hematuria. There are both two-way and three-way hematuria catheters (double and triple lumen). A condom catheter can be used by males and carries a lower risk of infection than an indwelling catheter.
Catheter diameters are sized by the French catheter scale (F). The most common sizes are 10 F (3.3mm) to 28 F (9.3mm). The clinician selects a size large enough to allow free flow of urine, and large enough to control leakage of urine around the catheter. A larger size is necessary when the urine is thick, bloody, or contains large amounts of sediment. Larger catheters, however, are more likely to damage the urethra. Some people develop allergies or sensitivities to latex after long-term latex catheter use making it necessary to use silicone or Teflon types.
Evidence does not support an important decrease in the risk of urinary tract infections when silver-alloy catheters are used.
Indications
Common indications for urinary catheterization include acute or chronic urinary retention (which can damage the kidneys) from conditions such as benign prostatic hyperplasia, orthopedic procedures that may limit a patient's movement, the need for accurate monitoring of input and output (such as in an ICU), urinary incontinence that may compromise the ability to heal wounds, and the effects of various surgical interventions involving the bladder, prostate, or bowel.
Intermittent self-catheterization may be indicated in cases of neurogenic bladder due to damage to the spinal cord or brain. This can be performed by the patient four to six times a day, using a clean technique. Nurses use a sterile technique to perform intermittent catheterization in hospital settings. For patients with neurogenic bladder due to spinal cord injury, intermittent catheterization (IC) is a standard method for bladder emptying. The technique is safe and effective and results in improved kidney and upper urinary tract status, lessening of vesicoureteral reflux and amelioration of continence. In addition to the clinical benefits, patient quality of life is enhanced by the increased independence and security offered by self-catheterization.
Catheter maintenance
A catheter that is left in place for more than a short period of time is generally attached to a drainage bag to collect the urine. This also allows for measurement of urine volume. There are three types of drainage bags: The first is a leg bag, a smaller drainage device that attaches by elastic bands to the leg. A leg bag is usually worn during the day, as it fits discreetly under pants or skirts, and is easily emptied into a toilet. The second type of drainage bag is a larger device called a down drain that may be used overnight. This device is hung on a hook under the patient's bed—never placed on the floor, due to the risk of bacterial infection. The third is called a belly bag and is secured around the waist. This bag can be worn at all times. It can be worn under the patient's underwear to provide a totally undetectable look.