Bladder catheterization is used to do the following:
- Obtain urine for examination
- Measure residual urine volume
- Relieve urinary retention or incontinence
- Deliver radiopaque contrast agents or drugs directly to the bladder
- Irrigate the bladder
Catheterization may be urethral or suprapubic.
Catheters vary by caliber, tip configuration, number of ports, balloon size, type of material, and length.
Caliber is standardized in French (F) units—also known as Charrière (Ch) units. Each unit is 0.33 mm, so a 14-F catheter is 4.6 mm in diameter. Sizes range from 12 to 24 F for adults and 8 to 12 F for children. Smaller catheters are usually sufficient for uncomplicated urinary drainage and useful for urethral strictures and bladder neck obstruction; bigger catheters are indicated for bladder irrigation and some cases of hemorrhage (eg, postoperatively or in hemorrhagic cystitis) and pyuria because clots could obstruct smaller caliber catheters.
Tips are straight in most catheters (eg, Robinson, whistle-tip) and are used for intermittent urethral catheterization (ie, catheter is removed immediately after bladder drainage). Foley catheters have a straight tip and an inflatable balloon for self-retention. Other self-retaining catheters may have an expanded tip, shaped like a mushroom (de Pezzer catheter) or a 4-winged perforated mushroom (Malecot catheter); they are used in suprapubic catheterization or nephrostomy. Elbowed (coudé) catheters, which may have balloons for self-retention, have a bent tip to ease catheterization through strictures or obstructions (eg, prostatic obstruction).
Ports are present in all catheters used for continuous urinary drainage. Many catheters have ports for balloon inflation, irrigation, or both (eg, 3-way Foley).
Balloons on self-retaining catheters have different volumes, from 2.5 to 5 mL in balloons intended for use in children and from 10 to 30 mL in balloons used in adults. Larger balloons and catheters are generally used to manage bleeding; traction on the catheter pulls the balloon against the base of the bladder and puts pressure on vessels, decreasing bleeding but potentially causing ischemia. It is recommended that the balloon be filled with plain water only.
Stylets are flexible metal guides inserted through the catheter to give stiffness and to facilitate insertion through strictures or obstructions and should only be used by physicians experienced with the technique.
Catheter material chosen depends on the intended use. Plastic, latex, or polyvinyl chloride catheters are for intermittent use. Latex with silicone, hydrogel, or silver alloy–coated polymer (to diminish bacterial colonization) catheters are for continuous use. Silicone catheters are used in patients with latex allergy.
A urethral catheter can be inserted by any health care practitioner and sometimes by patients themselves. No prior patient preparation is necessary; thus, the bladder is catheterized through the urethra unless the urethral route is contraindicated.
Relative contraindications are the following:
- Urethral strictures
- Current urinary tract infection (UTI)
- Urethral reconstruction or bladder surgery
- Urethral trauma
After the urethral meatus is carefully cleaned with an antibacterial solution, using strict sterile technique, the catheter is lubricated with sterile gel and gently advanced through the urethra into the bladder. Lidocaine gel may be injected through the male urethra before the catheter is passed to help relieve discomfort.
Complications of bladder catheterization include all of the following:
- Urethral or bladder trauma with bleeding or microscopic hematuria (common)
- UTI (common)
- Creation of false passages
- Scarring and strictures
- Bladder perforation (rare)
- Paraphimosis in uncircumcised males if the foreskin is not repositioned
Catheter-associated UTIs tend to increase morbidity, mortality, health care costs, and hospital length of stay. Recommendations for how to minimize the rates of these UTIs include the following:
- Restricting the use of urethral catheterization to indications that are clearly medically necessary (eg, not solely to minimize the number of bedside visits by health care providers made to empty urinals)
- Removing catheters as soon as possible
- Using strictly aseptic technique during catheter insertion
- Maintaining sterility and closure of the drainage system
Suprapubic catheterization via percutaneous cystostomy is done by a urologist or another experienced physician. No prior patient preparation is necessary. General indications include need for long-term bladder drainage and inability to pass a catheter through the urethra or contraindication to catheter use when bladder catheterization is necessary.
Contraindications include the following:
- Inability to define bladder location clinically or ultrasonographically
- An empty bladder
- Suspected pelvic or lower abdominal adhesions (eg, after pelvic or lower abdominal surgery or radiation therapy)
After the abdomen above the pubic area is numbed with a local anesthetic, a spinal needle is inserted into the bladder; ultrasound guidance is used if available. A catheter is then placed through a special trocar or over a guide wire threaded through the spinal needle. Prior lower abdominal surgery and previous radiation therapy contraindicate blind insertion. Complications include UTI, intestinal injury, and bleeding.
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