The use of a catheter may be necessary for diagnostic or therapeutic purposes.[7,8] A catheter is inserted through the urethra into the bladder to permit the drainage of urine.[7,9] Two minimally invasive procedures are indwelling catheterization and intermittent catheterization.
Reasons for Catheterization
As mentioned, there are diagnostic and therapeutic reasons that catheter insertion may be necessary. Diagnostic situations include instilling medication, obtaining urine specimens, monitoring urine output, and measuring residual volume after voiding. Catheterization may be used therapeutically for acute or chronic urinary retention and for the removal of blood and/or clots from the bladder.[7,8]
Types of Catheterization
Different circumstances require different types of catheterization. One type, intermittent catheterization, is the brief insertion of a catheter on one occasion or at regular intervals. The second type, indwelling catheterization, is the insertion of a catheter for a longer period of time, and the catheter is held in place by an inflated balloon in the bladder. Intermittent catheterization is used to obtain urine samples, empty the bladder, measure residual volume, instill medication, and instill contrast media into the bladder. Indwelling catheterization may be necessary for accurately measuring urine output, managing incontinence when other methods have failed, maintaining continuous urine output after surgery, and maintaining continuous urine output in patients with voiding difficulties resulting from neurologic disorders, as well as for immediate treatment of acute urinary retention.[9,10]
Male Catheterization Procedure
The patient should lie on a flat surface in the supine position. Catheterization should always be performed under sterile conditions.[8,11] Sterile gloves should be worn and the pubic region and inner thighs covered with sterile drapes.[8,11] Approximately 10 to 15 mL of viscous lidocaine should be injected into the urethra to anesthetize the area and distend the urethra for catheterization. Next, the penis should be grasped and held perpendicular to the body plane; the tip should be cleansed in a circular motion with cotton balls soaked in antiseptic solution. The catheter tip should be lubricated with sterile jelly or viscous lidocaine prior to insertion.[8,11] Then, the catheter should be gently introduced into the urethra and slowly advanced. Some resistance may be encountered near the external sphincter at around 16 to 20 cm. The catheter should be advanced until the return of urine is observed. This indicates proper positioning. If no urine is seen, the catheter may be obstructed by lidocaine or the bladder may be empty.[8,11] In this situation, the catheter should be flushed with saline to ensure free flow and appropriate placement.
If an indwelling catheter is being used, the balloon should be inflated with 10 mL of sterile water. No air or saline should be used.[8,11] Once the balloon is inflated, the catheter should be pulled back to set the balloon against the bladder. Then, the catheter should be anchored to the medial thigh and attached to a collection bag.[8,11] The collection bag should be placed below the level of the bladder in a dependent position.
Female Catheterization Procedure
The patient should lie on a flat surface in the supine position prior to catheter insertion. The legs should be apart and the feet together in a frog-legged position. Catheterization should always be performed under sterile conditions.[7,11] An absorbent pad should be placed under the patient's buttocks before sterile gloves are donned. The abdomen and superior pubic region should be covered with sterile drapes, antiseptic poured on preparation swabs, and the catheter tip lubricated.[7,11] The nondominant hand should be used to locate the urethra. The opening should be cleansed with the presoaked antiseptic swabs in a circular motion. Next, the catheter should be held in the dominant hand, gently introduced into the urethra, and slowly advanced. At about 4 cm in length, the female urethra is much shorter than the male urethra. Once urine starts to flow, the catheter should be inserted another 3 to 5 cm. If the flow of urine is slow or nonexistent, the catheter may be obstructed or placed in the wrong site, or the bladder may be empty. If this occurs, the catheter should be flushed with saline. If the saline returns freely, the catheter is properly placed.
If an indwelling catheter is used, the balloon should be filled with 10 mL of sterile water and the catheter gently pulled downward to set it in place.[7,11] No saline or air should be used. At this point, the catheter should be secured to the inner thigh and attached to a collection bag, which should be placed below the bladder in a convenient location.[7,11]
Products for catheterization are available commercially in prepackaged kits.[7,8] Usually, most needed items are included in the kit, with the exception of viscous lidocaine, a tape or device to secure the catheter to the patient, and antiseptic solution.
Many types and sizes of catheters are available (Figure 2). The most common material is latex, although silicone catheters are available for patients with latex allergies. The Foley catheter, the most frequently used type, is a double-lumen, straight-tipped catheter with a balloon at the end.[7,8] The Coudé catheter is helpful for facilitating placement in patients with prostatic enlargement. Its semirigid, curved tip should be pointed upward in the 12 o'clock position before insertion. For intermittent or one-time catheterization, a straight catheter is generally used. The triple-lumen catheter, which has an additional port for irrigation, is used to remove blood and/or clots.
Catheters are sized according to the French gauge system (French units [F]).[7,8] A size of 14-F to 16-F is appropriate for most females, although smaller units may be required for narrow urethras and larger units may be required if luminal obstruction is suspected (e.g., gross hematuria with clots). For males, 16-F to 18-F is generally acceptable; 12-F to 14-F may be needed if urethral stricture is observed, and 20-F to 24-F may be appropriate for patients with prostatic enlargement or hematuria.
Silver-alloy catheters have been shown to resist bacterial growth in indwelling catheters and should be considered for patients at high risk for infection.[7,8] In intermittent catheterization, there is no significant difference between catheter types in risk of urinary tract infections.
Clear, noncoated catheters are the most cost-effective, but other options also should be offered and considered.
Various collection systems are available. The leg-drainage system, night-drainage system, and urimeter-drainage system are typically for daytime use, nighttime use, and accurate measurement of urine output, respectively.
Complications of Catheterization
The main complication arising from catheterization is urinary tract infection, especially with the use of indwelling catheters.[7,8] The chance of infection increases by 3% to 10% per day of catheter use. With time, pyelonephritis, bacteremia, and urosepsis may develop. Urinary tract infections are less common with intermittent catheterization than with indwelling catheterization.[9,11] Trauma to the urethra or bladder, dislodgement, and blockage are other possible complications.[7–9]
Certain patient populations may be at increased risk for complications, such as the elderly and patients with diabetes, underlying renal insufficiency, or advanced, life-threatening illnesses. Thus, catheterization should be avoided unless absolutely necessary.[7,8,11] If catheterization is implemented, strict aseptic technique, maintenance of a closed collection system, and reduced duration are essential to minimize complications.[7,8]
US Pharmacist. 2013;38(8):27-30. © 2013 Jobson Publishing