6

Fundamentals of Urinary Tract

Drainage

John D. Denstedt; Thomas Tailly

Questions

1.A 24-French (Fr) Foley balloon catheter:

a.measures 24 cm long.

b.measures 8 mm in outer diameter.

c.measures 8 mm in inner diameter.

d.measures 1 cm in outer diameter.

e.can hold 24 mL of fluid in the retainment balloon.

2.Which of the following statements about the healthy adult male urethra is TRUE?

a.The external meatus is the narrowest and should allow a 24-Fr catheter to pass.

b.The bladder neck is the narrowest and should allow for a 24-Fr catheter to pass.

c.The prostatic urethra is the narrowest and should allow for a 24-Fr catheter to pass.

d.The prostatic urethra is the widest and should allow for a 24-Fr catheter to pass.

e.The external meatus is the widest and should allow for a 32-Fr catheter to pass.

3.Which measures can be taken to maximize anesthetic lubrication effect?

a.Lubricant at body temperature, 11 mL of fluid, fast instillation,

3 minutes indwelling time

b.Lubricant cooled to 4° C, 20 mL of fluid, slow instillation,

>15 minutes indwelling time

c.Lubricant at body temperature, 30 mL of fluid, slow instillation,

>25 minutes indwelling time

d.Lubricant cooled to 4° C, 11 mL of fluid, fast instillation, 3 minutes indwelling time

e.Lubricant cooled to 4° C, 11 mL of fluid, fast instillation, > 15 minutes indwelling time

4.Asymptomatic bacteriuria:

a.in the presence of a urinary catheter or ureter stent constitutes a catheter-associated urinary tract infection (CAUTI).

b.should be screened for in patients with a bladder catheter or indwelling ureteral stent.

c.should be treated as a urinary tract infection.

d.should not be screened for in nonpregnant patients with a bladder catheter or indwelling ureteral stent.

e.never evolves into a urinary tract infection.

5.What is the reported incidence of adjacent organ perforation during suprapubic catheter placement?

a.0% to 0.5%

b.< 0.1% to 2.7%

c.2.7% to 5%

d.5% to 10%

e.10% to 15%

6.Which of the following is NOT considered an indication for ureteral stent placement?

a.Ureteric obstruction in a patient with a solitary functional kidney

b.After a failed initial attempt at ureteroscopic treatment of a 12-mm ureteral stone

c.Persistent urinary extravasation after blunt renal trauma

d.After an uncomplicated ureteroscopy with no residual fragments

e.After a laparoscopic pyeloplasty for ureteropelvic obstruction

7.What is the most important contributing factor resulting in stent failure?

a.Small stent caliber

b.Too soft stent material

c.Ureteric obstruction by malignant external compression

d.Female gender

e.Biofilm-producing bacteria

Answers

1.b. Measures 8 mm in outer diameter. The French or Charrière scale was introduced by Joseph E. B. Charrière as a measurement unit for the circumference of a catheter. One unit on the scale equals 0.33 mm in external diameter. A 24-Fr catheter is therefore 8 mm in outer diameter.

2.a. The external meatus is the narrowest and should allow a 24-Fr catheter to pass. The caliber of the urethra varies throughout its course. The normal healthy external meatus should allow for a 24-Fr catheter to pass. Subsequent portions of the adult urethra have a larger caliber, the largest being the prostatic urethra with a caliber of approximately 32 Fr. The bladder neck should be large enough to allow for passage of a 28-Fr catheter.

3.b. Lubricant cooled to 4° C, 20 mL of fluid, slow instillation, > 15 minutes indwelling time. If anesthetic lubricant is to be used, the evidence available suggests instilling a minimum amount of 20 mL of cooled lubricant to be instilled slowly (> 3 to 10 seconds) and to allow for a minimum of 15 minutes of exposure to maximize benefit to the patient.

4.d. Should not be screened for in nonpregnant patients with a bladder catheter or indwelling ureteral stent. As of January 2009, the definition for CAUTI was modified to exclude asymptomatic bacteriuria. In current guidelines, a CAUTI is defined as significant bacteriuria in a patient with symptoms or signs indicating a urinary tract infection. As there is no evidence supporting that treatment of asymptomatic bacteriuria provides any benefit in reducing morbidity or mortality, EAU and IDSA guidelines specifically recommend against screening and treatment of asymptomatic bacteriuria.

5.b. < 0.1% to 2.7%. Surrounding organ injury is the most severe complication of suprapubic catheter placement and has been reported to occur in < 0.1% to 2.7% of procedures. Ultrasound-guided suprapubic catheter placement is the safest method to avoid this complication.

6.d. After an uncomplicated ureteroscopy with no residual fragments.

Indications for stent placement have changed in the past decade, with evidence-based medicine calling for stent placement only when specific conditions apply. Relieving obstruction in an obstructed solitary kidney is an absolute indication for stent placement. Current literature suggests that stenting after failed attempt at ureteroscopy may be beneficial. Meta-analysis has demonstrated that stent placement after uncomplicated ureteroscopy is not

beneficial.

7.e. Biofilm-producing bacteria. The most common cause of stent failure is biofilm-producing bacteria. Together with a prolonged indwelling time, this is the most important factor inducing encrustation, which can lead to stent blockage.

Chapter review

1.The average length of the adult male urethra is 20 cm; the average length of the female urethra is 4 cm. The average caliber of the female urethra is 22 Fr.

2.The use of feeding tubes as urethral catheters is to be discouraged.

3.The use of silicone catheters is associated with a lower incidence of urinary tract infections when compared with those made with latex.

4.Many studies have shown that topical anesthesia is not helpful in reducing pain in routine catheterization.

5.Routine use of catheter coatings is currently not supported by the available literature. Silicone catheters induce less inflammation and are preferred over latex for long-term catheterization.

6.For selected patients, a suprapubic catheter results in less discomfort than a urethral catheter.

7.More than 80% of patients experience ureteral stent-related pain affecting daily activities, and 58% report reduced work capacity.

8.The use of an α1-adrenergic blocker has been demonstrated to be

beneficial in reducing stent symptoms and pain.

9.Indwelling stent time should be limited to 4 months; after that it should be changed or removed. For pregnant patients, the time limit is 4 to 6 weeks.

10.A biofilm is the microorganism's attempt to control its immediate environment by limiting exposure to harmful factors while enhancing exposure to tropic factors. It usually consists of three layers: (1) innermost or linking film that is attached to the surface, (2) a base film that contains exopolysaccharides and the microorganisms, and (3) an outer layer, which is the point of egress or access for organisms.

11.Patients who are catheterized for urinary retention should be decompressed efficiently and completely—there is no role for prolonged slow decompression.

12.Long-term antibiotic prophylaxis for patients with uncomplicated chronic

indwelling urethral catheters or ureteral stents has not been shown to be beneficial.

13.Absolute indications for emergent upper track decompression include:

(1)bilateral obstruction (unilateral in the case of a solitary kidney) and

(2)an obstructed kidney that is infected.

14.One unit on the French scale equals 0.33 mm in external diameter.

15.The normal healthy external meatus should allow for a 24-Fr catheter to pass. Subsequent portions of the adult urethra have a larger caliber.

16.A catheter-associated urinary tract infection is defined as significant bacteriuria in a patient with symptoms or signs indicating a urinary tract infection. There is no evidence that treatment of asymptomatic bacteriuria provides any benefit in reducing morbidity or mortality.