Campbell-Walsh Urology, 11th Edition

PART IX

Urinary Lithiasis and Endourology

55

Lower Urinary Tract Calculi

Brian M. Benway; Sam B. Bhayani

Questions

1. Vesical calculus disease is usually associated with what condition in the United States?
2. Foreign bodies
3. Urinary tract infections
4. Catheterization
5. Bladder outlet obstruction
6. None of the above
7. Magnesium ammonium phosphate stones are most often formed in association with infection with which bacteria?
8. Pseudomonas
9. Providencia
10. Klebsiella
11. Staphylococcus
12. Proteus
13. Urease-producing bacteria hydrolyze urea into:
14. uric acid.
15. carbon monoxide.
16. carbon dioxide.
17. ammonium.
18. carbon dioxide and ammonium.
19. Which continent diversion has the highest risk of stone formation?
20. Mainz pouch
21. Kock pouch
22. Orthotopic hemi-Kock pouch
23. Indiana pouch
24. Cecal reservoir
25. Risk factors for the formation of stones in patients with urinary diversions include all of the following EXCEPT:
26. hypocitruria.
27. hyperchloremic metabolic acidosis.
28. hypercalciuria.
29. hyperoxaluria.
30. urinary tract infection.
31. What is the most accurate examination to document the presence of a bladder stone?
32. Ultrasonography
33. Excretory urography
34. Computed tomography
35. Cystoscopy
36. Plain (kidney/ureter/bladder) radiography
37. Appropriate treatment options for bladder calculi include all of the following EXCEPT:
38. irrigation with Suby solution G.
39. shockwave lithotripsy.
40. electrohydraulic lithotripsy.
41. ultrasonic lithotripsy.
42. holmium laser lithotripsy.
43. Urethral calculi in women are associated with which of the following?
44. Metabolic disturbances
45. Urethral stricture
46. Urethral diverticulum
47. Foreign bodies
48. None of the above
49. All of the following regarding primary bladder calculi in children are true EXCEPT:
50. the peak incidence is between the ages of 2 and 4 years.
51. patients usually present with multiple calculi.
52. the incidence is much higher in males than females.
53. formation is associated with low-phosphate diets.
54. formation is generally not associated with urinary tract infection.
55. Endoscopic management of bladder calculi is considered an acceptable intervention in:
56. a 26-year-old man with a history of neurogenic bladder who underwent augmentation cystoplasty at the age of 12 years and performs transurethral clean intermittent catheterization.
57. a 12-year-old girl with myelomeningocele who underwent bladder neck closure and creation of a Mitrofanoff catheterizable stoma at the age of 8 years.
58. a 76-year-old man with a history of bladder cancer who underwent cystectomy with Indiana pouch diversion.
59. a 65-year-old woman with a history of bladder cancer who underwent cystectomy with Kock pouch diversion.
60. a and d.
61. All of the following are true about bladder calculi in augmented bladders EXCEPT:
62. mean time to first stone formation is 2 to 6 years after augmentation.
63. catheterization through a Mitrofanoff stoma is associated with an increased risk of stone formation.
64. males are 3 to 10 times more likely to develop stones than females.
65. autoaugmentation is associated with a comparatively low risk of bladder stone formation.
66. All of the above are true.
67. Bladder stone formation in patients who have undergone kidney or pancreatic transplantation has been associated with:
68. nonabsorbable suture material used for the anastomosis.
69. incomplete bladder emptying due to diabetic cystopathy.
70. bacteriuria associated with included duodenal segments.
71. metabolic acidosis due to bicarbonate leak.
72. all of the above.
73. Which of the following is(are) typically associated with preputial calculi?
74. Stranguria
75. Phimosis
76. Voided urine culture positive for enterococcus or Escherichia coli
77. a and b.
78. b and c.
79. Which of the following statements about prostatic calculi is (are) TRUE?
80. Most prostatic calculi are asymptomatic
81. Large prostatic calculi most commonly involve the central zone of the prostate
82. Serum prostate-specific antigen and intraprostatic stone volume are directly correlated
83. Uric acid is the predominant component of prostatic calculi
84. All of the above

Answers

1. d. Bladder outlet obstruction.Bladder outlet obstruction may be an etiologic factor in more than 75% of bladder calculi cases and is most often related to benign prostatic hyperplasia.
2. e. Proteus.Whereas all these organisms produce urease, infection with Proteus species is most commonly associated with bladder calculi.
3. e. Carbon dioxide and ammonium.Urease hydrolyzes urea, forming ammonium and carbon dioxide, which increases urinary pH. Alkaline urine promotes supersaturation and precipitation of crystals of magnesium ammonium phosphate and carbonate apatite.
4. b. Kock pouch. The Kock pouch has a 4% to 43% incidence of stone formation. The predominant location of calculi in the Kock pouch is along staple lines of the afferent nipple valve.Substituting polyglycolic mesh for Marlex mesh in collar construction and limiting the number of staples has reduced the incidence of pouch calculi.
5. d. Hyperoxaluria.Patients with augments and diversions often have reabsorption of urinary solutes, especially sulfate and ammonium, through the intestinal segment with resultant metabolic disturbances. Chronic hyperchloremic metabolic acidosis may develop that, in turn, can result in hypercalciuria, hyperphosphaturia, hypermagnesuria, and hypocitraturia, predisposing the patient to urinary tract calculi.
6. d. Cystoscopy.Cystoscopy is the single most accurate examination to document the presence of a bladder calculus. Cystoscopy also assists in surgical planning by identifying prostatic enlargement, bladder diverticulum, or urethral stricture that may need correction before or in conjunction with the treatment of the stone.
7. a. Irrigation with Suby solution G (B. Braun Melsungen AG, Bethlehem, PA).Dissolution as primary treatment for bladder calculi can be protracted and is now rarely used.
8. c. Urethral diverticulum.Urethral calculi in females are exceptionally rare because of low rates of bladder calculi and a short urethra that permits passage of many smaller calculi. Calculi in the female urethra are typically associated with urethral diverticulum or urethrocele.
9. b. Patients usually present with multiple calculi. Primary bladder calculi in children are generally solitary and, once removed, recurrence is rare.Primary bladder calculi are 9 to 33 times more common in boys and are generally not associated with anatomic, functional, or infectious abnormalities. Cereal diets low in phosphate and animal protein are considered an important risk factor. Dietary modification results in a sharp decrease in stone formation.
10. e. a and d. Endoscopic instrumentation is not advised in patients who have undergone continent diversion with Indiana or Penn pouches, or for those with Mitrofanoff catheterizable stomas, because there is a significant risk of injury to the continence mechanisms and the narrow limbs themselves.Although percutaneous intervention is generally advised for the treatment of stones in patients with pouch diversions, the large caliber of the catheterizable limb and the nipple valve of the Kock pouch will tolerate endoscopic instrumentation. Transurethral endoscopic management is generally considered safe in augmented bladders, regardless of the type of substitution performed.
11. c. Males are 3 to 10 times more likely to develop stones than females. Unlike the nonaugmented population, females who have undergone augmentation cystoplasty are more likely to develop bladder calculi than males, likely owing to the higher incidence of cloacal abnormalities, which require additional procedures to establish continence.Bladder stone formation is more common in patients who have undergone intestinal substitution, as opposed to gastric and ureteric substitution or autoaugmentation, although the role of intestinal mucus in stone formation remains a matter of debate.
12. e. All of the above.All of the above have been found to be associated with bladder stone formation after renal transplantation, as well as pancreatic allografts, which are drained via the bladder. Although scant reports have noted stone formation on absorbable suture, the overwhelming majority of stone formation occurs in the presence of nonabsorbable suture or clip material.
13. e. b and c.Stranguria is a common presenting complaint in patients with migratory urethral calculi but is rarely associated with preputial calculi. Rather, progressive voiding complaints are the norm, with rare progression to urinary retention.
14. a. Most prostatic calculi are asymptomatic.The vast majority of prostatic calculi are asymptomatic and are an infrequent cause of lower urinary tract symptomatology. The majority of stones are found in the posterior and posterolateral zones of the prostate, and large stones are rarely found within the central zone. Serum prostate-specific antigen levels are unaffected by the presence of prostate calculi. Prostatic calculi are generally composed of calcium phosphate and calcium carbonate, which form on nidi of inspissated prostatic secretions.

Chapter review

1. Clean intermittent catheterization is associated with a significant reduction in risk of bladder stone formation compared with an indwelling catheter.
2. If a spinal cord injury patient has a bladder stone, the risk of a subsequent bladder calculus is markedly increased.
3. The holmium laser is the safest instrument to use to fragment bladder calculi.
4. Bladder outlet obstruction may be an etiologic factor in over 75% of bladder calculi cases and is most often related to benign prostatic hyperplasia.
5. Proteusspecies is the most commonly found organism associated with bladder calculi.
6. Patients with augments and diversions often have reabsorption of urinary solutes, especially sulfate and ammonium, through the intestinal segment with resultant metabolic disturbances. Chronic hyperchloremic metabolic acidosis may develop, which can, in turn, result in hypercalciuria, hyperphosphaturia, hypermagnesuria, and hypocitraturia, predisposing the patient to urinary tract calculi.
7. Primary bladder calculi in children are generally solitary and, once removed, recurrence is rare; cereal diets low in phosphate and animal protein are considered an important risk factor.
8. Endoscopic instrumentation is not advised in patients who have undergone continent diversion with Indiana or Penn pouches or for those with Mitrofanoff catheterizable stomas because there is a significant risk of injury to the continence mechanisms.
9. Prostatic calculi are generally composed of calcium phosphate and calcium carbonate, which form on nidi of inspissated prostatic secretions.