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7-Fundamentals of Instrumentation 177 and UrinaryTract Drainage

Urethral Catheterization

IndicationsThe most common indications for the use of a bladder cathetercan be broadly divided into two main categories:

to obtain drainageor to allow the instillation of diagnostic or therapeutic agents.

The relief of acute or chronic urinary retention due to either

bladder outlet obstruction or neurogenic bladder dysfunction isprobably the most common indication for urethral catheterization

(UC .)Following in frequency is its use to monitor urinary output

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Catheter SelectionThe size and type of urinary catheter used depends on the indicationfor catheter insertion, age of the patient, and type of fluidexpected to be drained. Currently there is a wide variety of cathetertypes. Catheters can be classified on the basis of material,

coating, number of channels , and tip form1french=0.33mm

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Catheter Size Based on AgeAGE IN YR CATHETER SIZE (FR)

<5 5-85-10 8-10

10-14 10>14 10-14

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•Silicone is relatively inert, causing less tissuereaction, and is associated with less bacterial adherence

than othercatheter materials.

•Evidence suggests that the

use of silicone catheters is associated with a lower incidence of

urinary tract infections compared with those made of latex

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Number of ChannelsThe most basic catheters are constructed with a single lumen to permit urinary drainage or

irrigation/instillation .Additional lumens are added to permit addition of a retention balloon (twoway catheter) and for

simultaneous drainage and irrigation (threeway catheter) .

The ability to allow bidirectional flow with a three-way catheter is particularly useful when there is need to drain thick fluid such as pus or blood from the bladder because it allows thinning of the solute,

preventing reaccumulation by rapid exchange of clean fluid in a washing effect .

The insertion of a three-way catheter for continuous bladder irrigation is most often performed after transurethral resection procedures of the bladder or prostate, which additionally can be combined with a largevolume retention balloon (30 to 50 mL), which under slight traction can often achieve complete hemostasis of the resected prostatic fossa.

It should be borne in mind, however, that the addition of a multichannel catheter is accomplished by decreasing the overall internal diameter or lumen of the main drainage channel; a 24-Fr three-way catheter has a smaller internal drainage diameter than a 24-Fr two-way, which has a narrower lumen than a 24-Fr one-way catheter.

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Technique of Catheter InsertionThe male urethra follows a sigmoid curse, with a proximal curveat the junction of the membranous and bulbar urethra and another

at the junction of the bulbar and penile urethra .

The adult maleurethra is approximately 18 to 20 cm in length, and its diameteris variable, from a mere slit to 6 mm during the passage of urine

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Only when the position of the catheter has been verified shouldthe retaining balloon be inflated, with the amount of fluid indicated

on the catheter .

Most catheters do safely permit twicethe indicated amount of fluid without risk of balloon rupture.

Sterile water is the preferred solution for balloon inflation. Air iscompressible and might leak, and electrolyte or glucose-basedsolutions can precipitate and occlude the tubing and valvemechanism

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Difficult CatheterizationDifficulty inserting a catheter into the bladder is most commonlydue to prostatic growth, urethral stricture(s), bladder neck contracture,or false passage from previous urethral instrumentation.Rarely it is the result of phimosis or urethral calculi .

If there is no clinical history of previous sexually transmittedinfections (STIs), catheterization, trauma, urethral surgery, orradiotherapy in an adult male over 40 years of age, the most likelycause is prostatic enlargement.

Using adequate urethral lubricationand a 16- or 18-Fr coudé tip silicone catheter is often successfulin this scenario.

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If multiple previously unsuccessful attemptshave been made and urethral trauma is suspected due to theappearance of a bloody urethral discharge, a false passage or astricture is likely.

A single atraumatic attempt can be made usinga 12-Fr silicon/straight or coudé tip catheter.

If this maneuver isunsuccessful, then depending on the availability of equipmentand the level of experience of the clinician, several other optionscan be considered. The authors’ preference is to use a flexibleCystoscope.

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Complications of UrethralCatheterization

UTIs account for 40% of all nosocomial infections .

The major risk factor is the use of urethral catheters, which are responsible for up to (80%) of UTIs in the hospital setting .

Risk factors for CAUTIs include patients requiring more than 6 days ofcatheterization, female gender, active nonurinary infection sites,preexisting medical conditions, malnutrition, renal insufficiency,

catheter insertion other than in the operating room, and havingdrainage tubing or a bag elevated above the level of the bladder

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A unique complication of urethral catheterization is the inabilityto remove the catheter from the bladder.

problem maybe due to a faulty valve, inflation channel blockage, or rarelycrystallization within the balloon.

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An inability to deflate a Foley balloon can be managed using a stepwise approach .

One should first attempt to place another 1 to2 mL of fluid in the balloon to ensure normal balloon contour,which may be important with the large-volume balloons .

Failingthis maneuver, the next step is to cut the inflation port.

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Other complications of urethral catheterization include hematuria,

urethral and meatal strictures, urethral perforation, and allergic reactions including anaphylaxis .

Especially at risk are patients with long-term indwellingcatheters, in whom other complications may also include malignant neoplasms (2.3% to 10%), stone formation (46% to 53%),

bladder neck and urethral erosions

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Suprapubic Catheterization•Indications•Suprapubic catheter (SC) insertion is most often selected for those•patients in whom urethral access is not possible such as complete•urethral stenosis, bladder neck contracture, and traumatic urethral•disruption.

Stent ComplicationsTechnique of Ureteral Stent InsertionStent SymptomsFrom a patient perspective, stent morbidity can be significant.Lower urinary tract symptoms such as frequency, urgency, dysuria,

and pain (flank or suprapubic) occur almost universally . More than 80% of patients experience stent-relatedpain affecting daily activities, 32% report sexual dysfunction, and

58% report reduced work capacity

Urinary Tract Infection

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Migrationrelated to a stent that was incorrectly sized for the patient’s height

Forgotten StentThis is a source of considerable impact on patient well-being and a threat to renal function

EncrustationMinor degrees of encrustation, particularly on the bladder curl,

are not uncommon in many stented patients. More extensiveencrustation often related to the forgotten/retained stent can beone of the most challenging tasks for the urologist requiringvarious endourologic interventions and on occasion open surgery.

If left untreated, extreme degrees of encrustation may lead tocompromise of the renal unit and even patient mortality

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Nephrostomy Tube Drainage•One of the most common indications for acute nephrostomy tube•insertion is to establish urinary tract drainage following a failed•attempt at retrograde stent insertion. An inability to insert a retrograde•stent may be due to several reasons including an impacted•ureteral stone or malignant obstruction. In patients with highgrade•bilateral ureteric obstruction or obstruction of a solitary•renal unit leading to obstructive nephropathy and metabolic•derangements, the ability to place the nephrostomy tube in a

ComplicationsNT-related complications can occur at the time of obtaining initial renal access, and additionally those that occur as a

result of the nephrostomy tube itself .It is estimated that the overall complication rate associated with NTs is approximately 8.8% to 10%.

Complications related to the access procedure include hematuria ,clot colic; and pulmonary injuries (pneumothorax, empyema, hydrothorax or hemothorax), which may be as high as 8% to 12% with upper calyceal approaches and

sepsis (1.3% to 2.2%) .Rarer complications include injuries to nearby organs (liver, spleen, and bowel) and arteriovenous fistulas.

The need for blood transfusionrelated to the NT insertion alone is reported to be as high as 3.2%in some series

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