Urinary Catheters and Ureteral Stents



Urinary Catheters and Ureteral Stents


Mary Van Meter Baker

John A. Occhino



Introduction

Urinary catheters and ureteral stents are tools commonly used by the urogynecologist for a variety of clinical indications. Catheters are hollow tubes used throughout medicine, but in urogynecology are used to drain urine from the bladder to outside the body. Stents, which are used to maintain patency of tubular structures, are useful in the field of urogynecology for identification and maintenance of integrity of the ureters. This chapter highlights the types of urinary catheters and ureteral stents, indications for use, and general instructions and risks associated with placement. The risk of infection associated with these devices constitutes a major consideration with their use and is discussed in the following text.


URINARY CATHETERS


Background and Indications

By allowing urine to freely drain from the bladder without coordinated micturition, urinary catheters are essential tools in gynecologic surgery. In addition to their role in draining and thereby preventing distention of the bladder during prolonged surgical procedures, catheters assist in the management of postoperative voiding dysfunction associated with many common pelvic reconstructive procedures. When bladder injury occurs, whether incidentally or intentionally, they prevent bladder distension and assist in healing. Urinary catheters bypass the need for conscious voiding in cases of immobility and may be indicated for long-term use in cases of neural or muscular injury to the bladder.


Foley

Transurethral catheters with self-retaining balloons were first described by Dr. Frederick Foley1 in 1929. The Foley catheter is a latex or silicone catheter with two channels: one for draining urine and a smaller valved channel that allows for inflation of a balloon to keep the catheter in place within the bladder. Foley catheters are sized in French units, with 3 French equivalent to 1.0 mm in diameter. Although smaller pediatric sizes are available, common sizes range from 10 to 28 French, with 14 and 16 French most commonly used for adult women. Balloon inflation amounts vary and are generally listed on packaging inserts, with a risk of expulsion and balloon rupture with under and over inflation, respectively. Of note, larger diameter Foley catheters are also used for mechanical cervical dilation in obstetrical induction of labor.


Suprapubic

Although transurethral catheters are common and allow bladder drainage through the natural orifice of the urethra, various pathologies necessitate urinary bypass of the urethra. Suprapubic catheters (SPCs) are inserted, often under direct cystoscopic guidance, transabdominally into the dome of the bladder. A distal balloon at the catheter tip allows for self-retention, although a stitch may be placed at the skin insertion site and wrapped around the catheter for reinforcement and to decrease postoperative drainage from the incision site. Although they are the most invasive and do require surgical placement, they are advantageous in that patients may attempt voiding while the SPC is in place (see Table 40.1 for patient instructions), and they may be associated with less bacterial growth and pain.


Self-Catheters

In addition to indwelling catheters, which are held in place with balloons inflated within the bladder to prevent expulsion of the catheter tubing, transurethral catheters may be inserted and removed by the patient for the purpose of bladder emptying. In addition to increasing patient comfort, self-intermittent catheterization (SIC) has been shown to decrease rates of catheter-associated urinary tract infections (CAUTIs) when compared to indwelling uretheral catheters.2 Therefore, SIC is an excellent option in patients experiencing postoperative voiding dysfunction. Patients do require education in order to successfully self-catheterize, but over 90% of patients can successfully learn self-catheterization expediently in a single teaching episode.3 Suggested
instructions for patient self-catheterization following surgery are detailed in Table 40.2.









Clinical Correlates


Patient instructions

See Tables 40.1 and 40.2.


Catheter-associated urinary tract infections avoidance and best practices

CAUTIs are the most common health care-associated infection and are the major morbidity associated with catheter usage. Risk of CAUTI increases with duration of use; therefore, catheters should be used for the minimal amount of time necessary to avoid unnecessary risk of infection. Estimated incidence is 5.3 per 100 catheterizations, with female sex as an independent factor for increased risk.4 However, urinary tract infection (UTI) is defined differently by different organizations and even different specialties, making accurate incidence reporting difficult. The National Surgical Quality Improvement Program has specific diagnostic criteria for postoperative UTI.5 CAUTI should be distinguished from asymptomatic bacteriuria, because most long-term indwelling catheters will result in eventual bacterial colonization, and treatment in the absence of symptoms risks development of multidrug-resistant organisms. Most experts agree that asymptomatic bacteriuria in the setting of catheters does not require antibiotic treatment.6