genitourinary disorders
Bladder Catheterization
Catheters
Catheters vary by caliber, tip configuration, number of ports, balloon size, type of material, and length. 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 Stricture and Tipsare straight in most catheters (eg, Robinson, whistle-tip) and are used for intermittent urethral catheterization (ie, catheter is removed immediately after bladder drainage). Foley (double-lumen latex) 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). Portsare present in all catheters used for continuous urinary drainage. Many catheters have ports for balloon inflation, irrigation, or both (eg, 3-way Foley). Balloonson 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. Styletsare 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 materialchosen 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. 