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BLADDER CALCULI IN THE PEDIATRIC AUGMENTED BLADDER
0022-5347/98/1603-10$03.00/0
Vol. 160,1096-1098,September 1998 Printed in U.S.A.
THE JOURYAL OF UROLOGY
Copyright 8 1998 by AMERICANUROL~CICAL ASSOCUTION,bc.
BLADDER CALCULI IN THE PEDIATRIC AUGMENTED BLADDER KEYIN M. KRONNER, ANTHONY J. CASALE,* MARK P. CAIN, MICHAEL J. ZERIN, MICHAEL A. KEATING AND RICHARD C. RINK From the Department of Pediatric Urology, James Whitcomb Riley Hospital for Children, Indiana Uniuersity School of Medicine, Indianapolis, Indiana
ABSTRACT
Purpose: Bladder augmentation is now a commonly accepted treatment in children with neuropathic bladder and other bladder anomalies. Bladder calculi have been reported in a third to a half of pediatric patients after bladder augmentation. We identify the incidence of bladder calculi and risk factors for stone formation in a large series of pediatric patients after bladder augmentation. Materials and Methods: We reviewed the records of 286 patients who underwent bladder augmentation between 1978 and 1994, assessed the incidence of and risk factors for bladder calculi, and reviewed treatment methods. Results: Bladder calculi developed in 29 of the 286 patients (10%)who underwent bladder augmentation. The type of bowel used for augmentation did not affect the rate of stone formation except stomach, which did not lead to stone formation in any case. Stones formed more commonly after bladder outlet resistance procedures and in patients with catheterizable abdominal wall stomas. Patients underwent open cystolithotomy or cystolitholapaxy with an overall 44% recurrence rate and no statistically significant difference between treatment methods. Conclusions: Bladder calculi are a known complication of bladder augmentation. An increased risk of stone formation is associated with bladder outlet resistance procedures and catheterizable abdominal wall stomas. Daily imgations to clear mucus and crystals as well as complete emptying of the augmented bladder may have important roles in decreasing stone formation. KEYWORDS: bladder, urinary diversion, calculi, abnormalities It has been nearly 100 years since the initial description of bladder augmentation using intestine in humans.' Bladder augmentation with bowel remains the current standard of care in some forms of neuropathic bladder and in some bladder anomalies. Despite the known limitations of bowel in the urinary tract, such as mucous production and absorption of solutes from the urine,2 to our knowledge no practical alternative has been discovered.The number of pediatric patients who undergo bladder augmentation continues to grow and with these numbers come inevitable complications. A common complication associated with enterocystoplasty is bladder calculi.* In the past bladder calculi in children were rarely reported in the United States. Between 1969 and 1985 Lebowitz and Vargas noted only 22 such patients, most of whom had undergone entero~ystoplasty.~ The incidence of pediatric bladder calculi associated with augmentation varies among reports. In 1990 Hendren and Hendren noted an 18%incidence in 129 patients: in 1992 Blyth et a1 described a 26% incidence in 875 and in 1993 Palmer et a1 noted an approximate 508 rate of bladder calculi in 48.6 In 1995 we previously reported an 8%incidence in our 231 participants.' It is generally accepted that urinary stasis, mucous production, bactenuria and in some cases foreign bodies, such as staples, may have a role in the formation of bladder calculi in the augmented bladder. However, it is unclear which factor is most important and why the incidence of calculi varies among studies. Another unanswered question is the optimal method of treatment for bladder calculi in pediatric patients with augmented bladders. Some suggest that open cystolithotomy is superior to endoscopic management because the stones may be removed Palmer et a1 have had good success with endoscopic management without the need for an
* Re
uests for re rints: Rile Hospital for Children No. 1739, 702
Barnha1 Drive, InJanapolis, Ldiana 46202.
i n ~ i s i o n .We ~ . ~present our updated experience with bladder calculi in a large series of children who underwent enterocystoplasty t o evaluate the incidence, risk factors and treatment. MATERIALS AND METHODS
We reviewed the records of 286 patients who underwent augmentation enterocystoplasty between 1978 and 1994. Minimum followup was 2 years and 208 patients (73%)were seen at our institution within 1year of this report. Followup studies consisted of at least kidney and bladder ultrasound or abdominal x-ray yearly with serum electrolyte and creatinine determinations. We documented the overall incidence of bladder calculi as well as the effect of infection and bowel type. Urinary stasis is generally thought to contributeto stone formation. Bladder neck procedures promote continence, and urinary retention within the bladder and abdominal wall stomas used for intermittent catheterization are believed to empty the bladder less completely than catheterization through the urethra. These procedures often accompany bladder augmentation and may affect stone formation. To study the effects of stasis we analyzed the effect of additional surgery that leads to urinary retention within the bladder and inhibits complete bladder emptying. Presenting complaint and diagnostic method were analyzed as well as stone composition and time to formation. Treatment methods and the risk of recurrent stone formation were also studied. Data were analyzed using Fisher's exact test, RESULTS
Bladder calculi developed in 29 of 286 patients (10%). Table 1 shows demographic data in the bladder calculi group.
1096
1097
BLADDER CALCULI IN THE PEDIATRIC AUGMENTED BLADDER
Mean time to diagnosis from the time of augmentation cysTABLE 2 toplasty was 68 months (range 12 to 183). Of the 29 patients Calculi Formation No. Pts. No. Calculi ('%I p Value 18 presented with recurrent urinary tract infections, while Bladder augmentation 165 10 ( 6 ) other presenting complaints included incontinence in 2 and Bladder augmentation + outlet re88 13 (14.7) 0.021 urosepsis in 1.Of the 8 asymptomatic patients 7 (27%)were sistance procedure 14 2 (14.3) 0.23 diagnosed on routine followup imaging and 1 was diagnosed Bladder augmentation + abdominal wall stoma incidentally at the time of another open bladder operation. 0.04 Bladder augmentation, outlet resis19 4 (21.1) The segments used to augment the bladder included stomtance procedure + abdominal ach in 37 cases, ileum in 113, sigmoid or cecum in 96, mixed wall stoma colon and ileum in 36, and ileum-stomach composite in 3. Stones formed in 11.5%of the ileal, 19.4%of the ileocolonic and 9.4%of the colonic augmentations. There was no statistically significant difference among these 3 groups in regard tically significant difference between the 2 treatment groups to stone formation. Bladder calculi developed in no patient (p = 0.25). In the group with recurrent stones there were 1to 7 recurrences per patient (average 1.75, table 3). with a gastric augmentation. Since the majority of patients presented with recurrent DISCUSSION bacteriuria, the infecting organisms were analyzed. Before the calculi were discovered 26 of the 29 patients (89%)had a The development of bladder calculi is a common complicahistory of positive urine cultures containing a urease- tion of augmentation cystoplasty. It is reported with increassplitting organism. A s expected, stone composition in 21 of 24 ing frequency in children as the number of augmentations cases (87.5%)was struvite. Calcium phosphate stones devel- increases in this population. Calculi represent a significant oped in 3 patients (12.5%) and in 5 no information was source of morbidity and they require surgical treatment. available on stone composition. Of the 286 study patients The etiology of bladder calculi in this population is likely with bladder augmentation urine culture information was multifactorial. The role of urinary stasis within the bladder is available in 242, including 230 (95%)with a history of chronic significant, and associated procedures that promote urine bacteriuria that was caused by urease-splitting organisms in retention or limit patient ability to empty the bladder com228 (94%). pletely are risk factors for stone formation. All bladder neck Only enterocystoplasty had been performed in 165 of the procedures intended to improve continence, such as the 286 patients. Procedures to provide continence at the bladder Kropp, Salle and Young-Dees-Leadbetter reconstruction opneck in 88 cases included artificial urinary sphincters in 48, erations as well as slings and artificial urinary sphincters, a Young-Dees-Leadbetter repair in 29, a Kropp bladder neck lead to urinary stasis within the bladder. The addition of an repair in 4, a fascia1 sling in 5 , a Marshall-Marchetti-Kantz abdominal wall catheterizable stoma improves the conveprocedure in 1 and a Salle bladder neck repair in 1. Entero- nience of catheterization but it is less efficient for bladder cystoplasty was accompanied by creation of a catheterizable emptying than a catheter passed through the more depenabdominal wall stoma only in 14 patients, and a combined dent urethra. The lowest incidence of stones in our series bladder neck and catheterizable stoma procedure was per- occurred in patients who underwent enterocystoplasty only, formed in 19. and the risk increased with additional surgical procedures. When evaluating stone risk, we found that bladder calculi Combined augmentation, bladder neck surgery and abdomideveloped in 6% of the patients who underwent only entero- nal wall stoma created the highest stone risk. cystoplasty, 14.7%augmentation plus a bladder neck proceStones developed with relative equal frequency with all dure, 14.3% augmentation plus catheterizable stoma cre- bowel types except stomach. The absence of stone formation ation, and 21.1% augmentation, bladder neck surgery and in gastric segments has been reported previously, and it held To our knowledge only Garzotto stoma creation. The increased risk of stone formation after a true in our e~perience.'.~.~ bladder neck procedure without a catheterizable abdominal and Walker previously reported a case of calculi in a gastrowall stoma was statistically significant compared with the cystoplasty and stone composition was uric acid.' These facts risk of enterocystoplasty only (p 50.021). The additional risk support the theory that mucous production and bacteriuria of a bladder neck procedure with a catheterizable stoma with urease-splitting organisms have an important role in compared to the risk of enterocystoplasty only was also sta- calculi development. Gastrocystoplasty has definite advantages in that it setistically significant (p S0.04). An isolated abdominal wall stoma with enterocystoplasty caused a greater risk than cretes little mucus and the gastric mucosa secretes acid, enterocystoplasty only but it was not statistically significant which decreases bladder pH, inhibits bacterial growth and prevents the basic milieu that allows struvite stones to de(p = 0.23, table 2). One of the 29 patients in whom bladder calculi developed velop. It is difficult to recommend gastric augmentation simspontaneously passed a stone, while the remaining 28 re- ply on the basis of a decreased risk of stone formation, since ceived treatment. Endoscopic cystolitholapaxy was per- gastrocystoplasty has unique complications, including the formed in 11 patients and 17 underwent open cystolithotomy. hematuria-dysuria syndrome and severe hypokalemic hypoAt least 1 year of followup was available in 27 cases, of which chloremic alkalosis.' In the previous studies of Blyth5 and Palmer' et a1 bactebladder calculi recurred in 12 (44%).Six of 11 patients (54%) treated endoscopicallyhad recurrent stones compared with 5 riuria with urease-splitting organisms contributed signifiof 15 (33%)treated with open surgery. There was no statis- cantly to stone formation. We also noted that our patients with bladder calculi had a high incidence of bacteriuria and struvite stone formation, although chronic bacteriuria was not an independent risk factor for bladder calculi formation. TABLE 1 Chronic bacteriuria developed in 95% of our patients, which NO.b o y a o . girls 10/19 Mean age at enterocystoplasty (range) No. diagnosis Myelodysplasia Classic enstrophy Cloaca1 enstrophy Imperforate anus Pelvic rhabdomyosmma Nonneurogenic neumgenic bladder
10 Yrs. (3-16) 22 2 2 1 1 1
TABLE3 Treatment
No. Pts.
Cystolitholapaxy Open cystolithotomy
11 15
No. Recurrences (%) 6 (54) 5 (33)
1098
BLADDER CALCULI IN THE PEDIATRIC AUGMENTED BLADDER
means t h a t a bladder calculus was actually more likely not to develop in a patient with chronic bacteriuria. The incidence of bladder calculi in our series is lower than in other reported series of pediatric bladder augmentation. An important factor is the high percentage of gastrocystoplasty, which comprises 14% of our cases. However, omitting gastrocystoplasty from our series results in a n 11.7% incidence, which is still the lowest rate reported. We believe that a second factor in the low incidence of bladder stones in our series is a routine management plan of lifelong daily bladder irrigations to remove mucus. Palmer et a1 addressed the role of bladder irrigation in the prevention of stones6 hut a prospective controlled study is needed. The optimal treatment of bladder calculi in patients with bladder augmentation remains a matter of opinion. While we noted a lower recurrence rate in patients treated with open cystolithotomy, the numbers were small and t h e difference in regard to endoscopic management was not statistically significant. Blyth et a1 also observed better success with open cystolithotomy," while Palmer et a1 reported excellent results with endoscopic treatment.",' Van Savage et a1 described a new approach using a percutaneous trocar and vacuum to remove stone fragments.' Pitfalls of the percutaneous approach include potential peritoneal extravasation, so that patients who underwent extraperitonealized bladder augmentation are better candidates for this approach.6 It is unclear which treatment modality is superior and success probably depends on a number of factors, including calculi size and number as well as bladder outlet surgery, which may limit the use of certain endoscopic equipment. The potential advantages of endoscopic surgery are the avoidance of open surgery through a n abdomen scarred by previous surgery and decreased patient morbidity in terms of duration of hospitalization and discomfort. Blyth e t a1 reported modest success with hemiacidrin irrigations but this was associated with a high recurrence rate, and they recommended open cystolithotomy as the treatment of choice." Bladder irrigation with hemiacidrin may have an adjunctive role in decreasing particles in the bladder after definitive treatment but it does not have a role in the removal of formed bladder stones. Blyth et a1 also performed extracorporeal shock wave lithotripsy without good success.
CONCLUSIONS
Bladder calculi develop in a significant number of children who have undergone enterocystoplasty, causing considerable morbidity. The etiology of stone formation is multifactorial, including urinary stasis a n d mucous production. In our series the risk of bladder stone formation increased with associated surgical procedures that promote urine retention within the bladder and inhibit complete bladder emptying. The type of bowel used for augmentation h a d no effect on stone formation except for stomach, which appeared to prevent calculi. The treatment of bladder stones in the pediatric patient with enterocystoplasty remains a matter of choice. While the recurrence rate in our series was lower after open surgery, this experience is not universal and the number of patients treated was too small to achieve statistical significance. REFERENCES
1. Orr, L. M., Thomley, M. W. and Campbell, M. P.: Ileocystoplasty for bladder enlargement. J. Urol., 7 9 250, 1958. 2. Rink, R. C., Hollensbe, D. and Adams, M. C.: Complications of
bladder augmentation in children and comparison of gastrointestinal segments. AUA Update Series, vol. 14, lesson 15, 1995. 3. Lebowitz, R. L. and Vargas, B.: Stones in the urinary bladder in children and young adults. AJR, 148 491,1987.
4. Hendren, W. H. and Hendren, R. B.: Bladder augmentation experience with 129 children and young adults. J. Urol., 144: 445,1990. 5. Blyth, B., Ewalt, D. H., Duckett, J. W. and Snyder, H. M., 111: Lithogenic properties of enterocystoplasty. J. Urol., 148 575, 1992. 6. Palmer, L. S., Franco, I., Kogan, S. J., Reda, E., Gill, B. and Levitt, S. B.: Urolithiasis in children following augmentation cystoplasty. J. Urol., 150 726, 1993. 7. Palmer, L. S.,Franco, I., Reda, E. F., Kogan, S. J. and Levitt, S. B.: Endoscopic management of bladder calculi following augmentation cystoplasty. Urology, 44: 902,1994. 8. Garzotto, M.G. and Walker, R. D.: Uric acid stone and gastric bladder augmentation. J. Urol., 153 1976,1995. 9. Van Savage, J. G., Khoury, A. E., McLorie, G. A. and Churchill, B. M.: Percutaneous vacuum vesicolithotomy under direct vision: a new technique. J. Urol., 156 706, 1996.
Vol. 160,1096-1098,September 1998 Printed in U.S.A.
THE JOURYAL OF UROLOGY
Copyright 8 1998 by AMERICANUROL~CICAL ASSOCUTION,bc.
BLADDER CALCULI IN THE PEDIATRIC AUGMENTED BLADDER KEYIN M. KRONNER, ANTHONY J. CASALE,* MARK P. CAIN, MICHAEL J. ZERIN, MICHAEL A. KEATING AND RICHARD C. RINK From the Department of Pediatric Urology, James Whitcomb Riley Hospital for Children, Indiana Uniuersity School of Medicine, Indianapolis, Indiana
ABSTRACT
Purpose: Bladder augmentation is now a commonly accepted treatment in children with neuropathic bladder and other bladder anomalies. Bladder calculi have been reported in a third to a half of pediatric patients after bladder augmentation. We identify the incidence of bladder calculi and risk factors for stone formation in a large series of pediatric patients after bladder augmentation. Materials and Methods: We reviewed the records of 286 patients who underwent bladder augmentation between 1978 and 1994, assessed the incidence of and risk factors for bladder calculi, and reviewed treatment methods. Results: Bladder calculi developed in 29 of the 286 patients (10%)who underwent bladder augmentation. The type of bowel used for augmentation did not affect the rate of stone formation except stomach, which did not lead to stone formation in any case. Stones formed more commonly after bladder outlet resistance procedures and in patients with catheterizable abdominal wall stomas. Patients underwent open cystolithotomy or cystolitholapaxy with an overall 44% recurrence rate and no statistically significant difference between treatment methods. Conclusions: Bladder calculi are a known complication of bladder augmentation. An increased risk of stone formation is associated with bladder outlet resistance procedures and catheterizable abdominal wall stomas. Daily imgations to clear mucus and crystals as well as complete emptying of the augmented bladder may have important roles in decreasing stone formation. KEYWORDS: bladder, urinary diversion, calculi, abnormalities It has been nearly 100 years since the initial description of bladder augmentation using intestine in humans.' Bladder augmentation with bowel remains the current standard of care in some forms of neuropathic bladder and in some bladder anomalies. Despite the known limitations of bowel in the urinary tract, such as mucous production and absorption of solutes from the urine,2 to our knowledge no practical alternative has been discovered.The number of pediatric patients who undergo bladder augmentation continues to grow and with these numbers come inevitable complications. A common complication associated with enterocystoplasty is bladder calculi.* In the past bladder calculi in children were rarely reported in the United States. Between 1969 and 1985 Lebowitz and Vargas noted only 22 such patients, most of whom had undergone entero~ystoplasty.~ The incidence of pediatric bladder calculi associated with augmentation varies among reports. In 1990 Hendren and Hendren noted an 18%incidence in 129 patients: in 1992 Blyth et a1 described a 26% incidence in 875 and in 1993 Palmer et a1 noted an approximate 508 rate of bladder calculi in 48.6 In 1995 we previously reported an 8%incidence in our 231 participants.' It is generally accepted that urinary stasis, mucous production, bactenuria and in some cases foreign bodies, such as staples, may have a role in the formation of bladder calculi in the augmented bladder. However, it is unclear which factor is most important and why the incidence of calculi varies among studies. Another unanswered question is the optimal method of treatment for bladder calculi in pediatric patients with augmented bladders. Some suggest that open cystolithotomy is superior to endoscopic management because the stones may be removed Palmer et a1 have had good success with endoscopic management without the need for an
* Re
uests for re rints: Rile Hospital for Children No. 1739, 702
Barnha1 Drive, InJanapolis, Ldiana 46202.
i n ~ i s i o n .We ~ . ~present our updated experience with bladder calculi in a large series of children who underwent enterocystoplasty t o evaluate the incidence, risk factors and treatment. MATERIALS AND METHODS
We reviewed the records of 286 patients who underwent augmentation enterocystoplasty between 1978 and 1994. Minimum followup was 2 years and 208 patients (73%)were seen at our institution within 1year of this report. Followup studies consisted of at least kidney and bladder ultrasound or abdominal x-ray yearly with serum electrolyte and creatinine determinations. We documented the overall incidence of bladder calculi as well as the effect of infection and bowel type. Urinary stasis is generally thought to contributeto stone formation. Bladder neck procedures promote continence, and urinary retention within the bladder and abdominal wall stomas used for intermittent catheterization are believed to empty the bladder less completely than catheterization through the urethra. These procedures often accompany bladder augmentation and may affect stone formation. To study the effects of stasis we analyzed the effect of additional surgery that leads to urinary retention within the bladder and inhibits complete bladder emptying. Presenting complaint and diagnostic method were analyzed as well as stone composition and time to formation. Treatment methods and the risk of recurrent stone formation were also studied. Data were analyzed using Fisher's exact test, RESULTS
Bladder calculi developed in 29 of 286 patients (10%). Table 1 shows demographic data in the bladder calculi group.
1096
1097
BLADDER CALCULI IN THE PEDIATRIC AUGMENTED BLADDER
Mean time to diagnosis from the time of augmentation cysTABLE 2 toplasty was 68 months (range 12 to 183). Of the 29 patients Calculi Formation No. Pts. No. Calculi ('%I p Value 18 presented with recurrent urinary tract infections, while Bladder augmentation 165 10 ( 6 ) other presenting complaints included incontinence in 2 and Bladder augmentation + outlet re88 13 (14.7) 0.021 urosepsis in 1.Of the 8 asymptomatic patients 7 (27%)were sistance procedure 14 2 (14.3) 0.23 diagnosed on routine followup imaging and 1 was diagnosed Bladder augmentation + abdominal wall stoma incidentally at the time of another open bladder operation. 0.04 Bladder augmentation, outlet resis19 4 (21.1) The segments used to augment the bladder included stomtance procedure + abdominal ach in 37 cases, ileum in 113, sigmoid or cecum in 96, mixed wall stoma colon and ileum in 36, and ileum-stomach composite in 3. Stones formed in 11.5%of the ileal, 19.4%of the ileocolonic and 9.4%of the colonic augmentations. There was no statistically significant difference among these 3 groups in regard tically significant difference between the 2 treatment groups to stone formation. Bladder calculi developed in no patient (p = 0.25). In the group with recurrent stones there were 1to 7 recurrences per patient (average 1.75, table 3). with a gastric augmentation. Since the majority of patients presented with recurrent DISCUSSION bacteriuria, the infecting organisms were analyzed. Before the calculi were discovered 26 of the 29 patients (89%)had a The development of bladder calculi is a common complicahistory of positive urine cultures containing a urease- tion of augmentation cystoplasty. It is reported with increassplitting organism. A s expected, stone composition in 21 of 24 ing frequency in children as the number of augmentations cases (87.5%)was struvite. Calcium phosphate stones devel- increases in this population. Calculi represent a significant oped in 3 patients (12.5%) and in 5 no information was source of morbidity and they require surgical treatment. available on stone composition. Of the 286 study patients The etiology of bladder calculi in this population is likely with bladder augmentation urine culture information was multifactorial. The role of urinary stasis within the bladder is available in 242, including 230 (95%)with a history of chronic significant, and associated procedures that promote urine bacteriuria that was caused by urease-splitting organisms in retention or limit patient ability to empty the bladder com228 (94%). pletely are risk factors for stone formation. All bladder neck Only enterocystoplasty had been performed in 165 of the procedures intended to improve continence, such as the 286 patients. Procedures to provide continence at the bladder Kropp, Salle and Young-Dees-Leadbetter reconstruction opneck in 88 cases included artificial urinary sphincters in 48, erations as well as slings and artificial urinary sphincters, a Young-Dees-Leadbetter repair in 29, a Kropp bladder neck lead to urinary stasis within the bladder. The addition of an repair in 4, a fascia1 sling in 5 , a Marshall-Marchetti-Kantz abdominal wall catheterizable stoma improves the conveprocedure in 1 and a Salle bladder neck repair in 1. Entero- nience of catheterization but it is less efficient for bladder cystoplasty was accompanied by creation of a catheterizable emptying than a catheter passed through the more depenabdominal wall stoma only in 14 patients, and a combined dent urethra. The lowest incidence of stones in our series bladder neck and catheterizable stoma procedure was per- occurred in patients who underwent enterocystoplasty only, formed in 19. and the risk increased with additional surgical procedures. When evaluating stone risk, we found that bladder calculi Combined augmentation, bladder neck surgery and abdomideveloped in 6% of the patients who underwent only entero- nal wall stoma created the highest stone risk. cystoplasty, 14.7%augmentation plus a bladder neck proceStones developed with relative equal frequency with all dure, 14.3% augmentation plus catheterizable stoma cre- bowel types except stomach. The absence of stone formation ation, and 21.1% augmentation, bladder neck surgery and in gastric segments has been reported previously, and it held To our knowledge only Garzotto stoma creation. The increased risk of stone formation after a true in our e~perience.'.~.~ bladder neck procedure without a catheterizable abdominal and Walker previously reported a case of calculi in a gastrowall stoma was statistically significant compared with the cystoplasty and stone composition was uric acid.' These facts risk of enterocystoplasty only (p 50.021). The additional risk support the theory that mucous production and bacteriuria of a bladder neck procedure with a catheterizable stoma with urease-splitting organisms have an important role in compared to the risk of enterocystoplasty only was also sta- calculi development. Gastrocystoplasty has definite advantages in that it setistically significant (p S0.04). An isolated abdominal wall stoma with enterocystoplasty caused a greater risk than cretes little mucus and the gastric mucosa secretes acid, enterocystoplasty only but it was not statistically significant which decreases bladder pH, inhibits bacterial growth and prevents the basic milieu that allows struvite stones to de(p = 0.23, table 2). One of the 29 patients in whom bladder calculi developed velop. It is difficult to recommend gastric augmentation simspontaneously passed a stone, while the remaining 28 re- ply on the basis of a decreased risk of stone formation, since ceived treatment. Endoscopic cystolitholapaxy was per- gastrocystoplasty has unique complications, including the formed in 11 patients and 17 underwent open cystolithotomy. hematuria-dysuria syndrome and severe hypokalemic hypoAt least 1 year of followup was available in 27 cases, of which chloremic alkalosis.' In the previous studies of Blyth5 and Palmer' et a1 bactebladder calculi recurred in 12 (44%).Six of 11 patients (54%) treated endoscopicallyhad recurrent stones compared with 5 riuria with urease-splitting organisms contributed signifiof 15 (33%)treated with open surgery. There was no statis- cantly to stone formation. We also noted that our patients with bladder calculi had a high incidence of bacteriuria and struvite stone formation, although chronic bacteriuria was not an independent risk factor for bladder calculi formation. TABLE 1 Chronic bacteriuria developed in 95% of our patients, which NO.b o y a o . girls 10/19 Mean age at enterocystoplasty (range) No. diagnosis Myelodysplasia Classic enstrophy Cloaca1 enstrophy Imperforate anus Pelvic rhabdomyosmma Nonneurogenic neumgenic bladder
10 Yrs. (3-16) 22 2 2 1 1 1
TABLE3 Treatment
No. Pts.
Cystolitholapaxy Open cystolithotomy
11 15
No. Recurrences (%) 6 (54) 5 (33)
1098
BLADDER CALCULI IN THE PEDIATRIC AUGMENTED BLADDER
means t h a t a bladder calculus was actually more likely not to develop in a patient with chronic bacteriuria. The incidence of bladder calculi in our series is lower than in other reported series of pediatric bladder augmentation. An important factor is the high percentage of gastrocystoplasty, which comprises 14% of our cases. However, omitting gastrocystoplasty from our series results in a n 11.7% incidence, which is still the lowest rate reported. We believe that a second factor in the low incidence of bladder stones in our series is a routine management plan of lifelong daily bladder irrigations to remove mucus. Palmer et a1 addressed the role of bladder irrigation in the prevention of stones6 hut a prospective controlled study is needed. The optimal treatment of bladder calculi in patients with bladder augmentation remains a matter of opinion. While we noted a lower recurrence rate in patients treated with open cystolithotomy, the numbers were small and t h e difference in regard to endoscopic management was not statistically significant. Blyth et a1 also observed better success with open cystolithotomy," while Palmer et a1 reported excellent results with endoscopic treatment.",' Van Savage et a1 described a new approach using a percutaneous trocar and vacuum to remove stone fragments.' Pitfalls of the percutaneous approach include potential peritoneal extravasation, so that patients who underwent extraperitonealized bladder augmentation are better candidates for this approach.6 It is unclear which treatment modality is superior and success probably depends on a number of factors, including calculi size and number as well as bladder outlet surgery, which may limit the use of certain endoscopic equipment. The potential advantages of endoscopic surgery are the avoidance of open surgery through a n abdomen scarred by previous surgery and decreased patient morbidity in terms of duration of hospitalization and discomfort. Blyth e t a1 reported modest success with hemiacidrin irrigations but this was associated with a high recurrence rate, and they recommended open cystolithotomy as the treatment of choice." Bladder irrigation with hemiacidrin may have an adjunctive role in decreasing particles in the bladder after definitive treatment but it does not have a role in the removal of formed bladder stones. Blyth et a1 also performed extracorporeal shock wave lithotripsy without good success.
CONCLUSIONS
Bladder calculi develop in a significant number of children who have undergone enterocystoplasty, causing considerable morbidity. The etiology of stone formation is multifactorial, including urinary stasis a n d mucous production. In our series the risk of bladder stone formation increased with associated surgical procedures that promote urine retention within the bladder and inhibit complete bladder emptying. The type of bowel used for augmentation h a d no effect on stone formation except for stomach, which appeared to prevent calculi. The treatment of bladder stones in the pediatric patient with enterocystoplasty remains a matter of choice. While the recurrence rate in our series was lower after open surgery, this experience is not universal and the number of patients treated was too small to achieve statistical significance. REFERENCES
1. Orr, L. M., Thomley, M. W. and Campbell, M. P.: Ileocystoplasty for bladder enlargement. J. Urol., 7 9 250, 1958. 2. Rink, R. C., Hollensbe, D. and Adams, M. C.: Complications of
bladder augmentation in children and comparison of gastrointestinal segments. AUA Update Series, vol. 14, lesson 15, 1995. 3. Lebowitz, R. L. and Vargas, B.: Stones in the urinary bladder in children and young adults. AJR, 148 491,1987.
4. Hendren, W. H. and Hendren, R. B.: Bladder augmentation experience with 129 children and young adults. J. Urol., 144: 445,1990. 5. Blyth, B., Ewalt, D. H., Duckett, J. W. and Snyder, H. M., 111: Lithogenic properties of enterocystoplasty. J. Urol., 148 575, 1992. 6. Palmer, L. S., Franco, I., Kogan, S. J., Reda, E., Gill, B. and Levitt, S. B.: Urolithiasis in children following augmentation cystoplasty. J. Urol., 150 726, 1993. 7. Palmer, L. S.,Franco, I., Reda, E. F., Kogan, S. J. and Levitt, S. B.: Endoscopic management of bladder calculi following augmentation cystoplasty. Urology, 44: 902,1994. 8. Garzotto, M.G. and Walker, R. D.: Uric acid stone and gastric bladder augmentation. J. Urol., 153 1976,1995. 9. Van Savage, J. G., Khoury, A. E., McLorie, G. A. and Churchill, B. M.: Percutaneous vacuum vesicolithotomy under direct vision: a new technique. J. Urol., 156 706, 1996.