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A new method for ureteral implantation: the procedure of choice for kidney recipients with very small, defunctionalized bladders
A New Method for Ureteral Implantation: The Procedure of Choice for Kidney Recipients With Very Small, Defunctionalized Bladders O. Salvatierra, Jr
M
AJOR, almost insurmountable deterrents exist to the use of the very small– capacity, defunctionalized, non-neurogenic urinary bladder in renal transplantation, ie, the technical difficulty in performing a satisfactory ureteral implantation with conventional methods and the potential secondary problems with high-grade ureteral reflux and obstruction. Alternatives are less than ideal and include transplantation into a bowel-augmented urinary bladder with intermittent self-catheterization, ileal conduit urinary diversion, or avoidance of transplantation and relegating the patient to life-long dialysis.1
METHODS Eight consecutive patients (ages 13 months to 29 years) with small, defunctionalized urinary bladders underwent a new method of intravesical implantation of the transplant ureter. The mean capacity of these bladders was 18.5 ⫾ 13.1 mL (range, 6 to 45 mL), with the bladders defunctionalized for a mean 81.6 ⫾ 24.3% of the patients’ total lifetime. Follow-up post-transplantation ranged from 4 to 16 months. The technique involved placement of the transplant ureter into a shallow, mucosa-denuded, rectangular trough that extended from a superiorly placed ureteral hiatus distally to the trigone.1 We hypothesized from wartime experiences2 and known experimental regeneration capabilities of transitional epithelium of the mammalian urinary bladder,3 that the mucosal margins on the two lateral aspects of the rectangular trough would grow over the anterior surface of the ureter until they met the advancing mucosal edges from the contralateral side to form a natural neosubmucosal tunnel.
RESULTS
Post-transplantation cystoscopic examination showed bladder mucosal regeneration and growth over the ureter, confirming the spontaneous development of a good length neosubmucosal tunnel. No patients showed evidence of ureteral reflux on cystography, or ureteral obstruction on serial renal ultrasounds, whereas an immediate prior cohort of four consecutive patients with bladder capacities less than or equal to 30 mL showed that three of four had ureteral reflux (P ⫽ .02) and four of four developed hydronephrosis (P ⫽ .002). All urinary bladders in the present cohort enlarged to expected normal or near-normal capacities. In seven of eight patients, the serum creatinine level was stable throughout the entire follow-up period and
ranged from 0.3 to 1.0 mg/dL at last follow-up. One patient had a serum creatinine level of 2.1 mg/dL after three rejection episodes. In contrast, all four patients in the retrospective cohort showed increased serum creatinine levels (range, 0.3 to 0.6 mg/mL above baseline) with peak severity of their hydronephrosis.
DISCUSSION
The results described in this report with our very small bladder capacities in non-neurogenic, defunctionalized bladders are not likely to be duplicated by either an extravesical ureteral implantation, or by an attempted intravesical, submucosal tunnel in these contracted and often severely scarred urinary bladders. This appears to be verified by the statistically significant differences in reflux and hydronephrosis between our current and retrospective groups of patients. The most that one can usually obtain from an extravesical ureteral implantation in the smallest bladders is a simple, right-angle “plug-in” attachment of the ureter because there is insufficient bladder muscle to effect coverage of the distal ureter after its anastomosis. This extravesical anastomosis, therefore, appears destined to reflux because there is no muscle buttressing the distal ureter to create the valve-like mechanism that prevents reflux.4 It is also well known that high intravesical pressure can, of itself, convert a previously anatomically competent ureterovesical junction to one that refluxes.5 The inherent high intravesical pressure during the period of small bladder enlargement after transplantation can, thereby, only enhance ureteral back pressure through an already anatomically incompetent ureterovesical junction, causing significant secondary hydroureteronephrosis, as occurred in our retrospective patient cohort, with possible impairment of renal function. The consequences of reflux with an abnormal, small bladder are, therefore, different and more serious than those with the milder forms of reflux sometimes
From the Departments of Surgery and Pediatrics, Stanford University School of Medicine, Palo Alto, California. Address reprint requests to Oscar Salvatierra, Jr, MD, Department of Surgery, Stanford University School of Medicine, Palo Alto, CA 94304.
© 1999 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
0041-1345/99/$–see front matter PII S0041-1345(99)00661-2
Transplantation Proceedings, 31, 3041–3042 (1999)
3041
3042
encountered in kidney recipients who have normal bladders.6 With regard to the actual management of the small, defunctionalized bladders, one needs to first accept the important fact that there is no perfect treatment.1 The risks of transplantation into a small, abnormal, non-neurogenic bladder should then be balanced against the risks and complications with a bowel-augmented urinary bladder as the receptacle for the transplant ureter.1 Most likely in this analysis, our reported implantation technique will be deemed the most appropriate procedure. In the unlikely event that this procedure were to fail, one can then resort to urinary bladder augmentation with bowel or ileal conduit diversion. The most important reasons for initial use of the native bladder and our implantation technique over other alternatives are the probable high likelihood of success, the restoration of normal urethral voiding function, and that most patients will be spared extensive additional procedures with their potential complications. In addition, the need for intermittent self-catheterization with an augmented urinary bladder or an appliance with an ileal conduit are avoided. This should also lead to a lesser likelihood of urinary infection. With these considerations in mind, our procedure would appear to have the potential to both greatly enhance patient quality of life and provide for significant cost-effectiveness over alternative approaches.1
SALVATIERRA
CONCLUSIONS
This novel technique for ureteral implantation successfully capitalizes on the regenerative potential of the bladder mucosa, resulting in a physiologic, anatomically natural, and very effective neosubmucosal tunnel. It appears to guarantee success against both ureteral reflux and obstruction, no matter how small the urinary bladder, and offers no hindrance to enlarging the bladder to near normal capacity post-transplantation. The implantation technique is simple and safe, and its use should eliminate the reluctance to use these bladders. Moreover, this procedure offers a major incentive for the successful rehabilitation of small, defunctionalized, non-neurogenic bladders after kidney transplantation.1 REFERENCES 1. Salvatierra O, Sarwal M, Alexander S, et al: Transplantation 68:731, 1999 2. Salvatierra O, Rigdon WO, Norris DM, et al: J Urol 191:615, 1969 3. Connolly JG, Morales A, Minnaker L, et al: Investigative Urol 8:481, 1971 4. Tanagho EA: Br J Urol 42:410, 1970 5. Atala A, Keating M: In Walsh PC, Retik AB, Vaughn ED, et al (eds.) Campbell’s Urology. Philadelphia, PA: Saunders; 1998, p 1859 6. Salvatierra O: Pediatr Transplant 3:171, 1999
M
AJOR, almost insurmountable deterrents exist to the use of the very small– capacity, defunctionalized, non-neurogenic urinary bladder in renal transplantation, ie, the technical difficulty in performing a satisfactory ureteral implantation with conventional methods and the potential secondary problems with high-grade ureteral reflux and obstruction. Alternatives are less than ideal and include transplantation into a bowel-augmented urinary bladder with intermittent self-catheterization, ileal conduit urinary diversion, or avoidance of transplantation and relegating the patient to life-long dialysis.1
METHODS Eight consecutive patients (ages 13 months to 29 years) with small, defunctionalized urinary bladders underwent a new method of intravesical implantation of the transplant ureter. The mean capacity of these bladders was 18.5 ⫾ 13.1 mL (range, 6 to 45 mL), with the bladders defunctionalized for a mean 81.6 ⫾ 24.3% of the patients’ total lifetime. Follow-up post-transplantation ranged from 4 to 16 months. The technique involved placement of the transplant ureter into a shallow, mucosa-denuded, rectangular trough that extended from a superiorly placed ureteral hiatus distally to the trigone.1 We hypothesized from wartime experiences2 and known experimental regeneration capabilities of transitional epithelium of the mammalian urinary bladder,3 that the mucosal margins on the two lateral aspects of the rectangular trough would grow over the anterior surface of the ureter until they met the advancing mucosal edges from the contralateral side to form a natural neosubmucosal tunnel.
RESULTS
Post-transplantation cystoscopic examination showed bladder mucosal regeneration and growth over the ureter, confirming the spontaneous development of a good length neosubmucosal tunnel. No patients showed evidence of ureteral reflux on cystography, or ureteral obstruction on serial renal ultrasounds, whereas an immediate prior cohort of four consecutive patients with bladder capacities less than or equal to 30 mL showed that three of four had ureteral reflux (P ⫽ .02) and four of four developed hydronephrosis (P ⫽ .002). All urinary bladders in the present cohort enlarged to expected normal or near-normal capacities. In seven of eight patients, the serum creatinine level was stable throughout the entire follow-up period and
ranged from 0.3 to 1.0 mg/dL at last follow-up. One patient had a serum creatinine level of 2.1 mg/dL after three rejection episodes. In contrast, all four patients in the retrospective cohort showed increased serum creatinine levels (range, 0.3 to 0.6 mg/mL above baseline) with peak severity of their hydronephrosis.
DISCUSSION
The results described in this report with our very small bladder capacities in non-neurogenic, defunctionalized bladders are not likely to be duplicated by either an extravesical ureteral implantation, or by an attempted intravesical, submucosal tunnel in these contracted and often severely scarred urinary bladders. This appears to be verified by the statistically significant differences in reflux and hydronephrosis between our current and retrospective groups of patients. The most that one can usually obtain from an extravesical ureteral implantation in the smallest bladders is a simple, right-angle “plug-in” attachment of the ureter because there is insufficient bladder muscle to effect coverage of the distal ureter after its anastomosis. This extravesical anastomosis, therefore, appears destined to reflux because there is no muscle buttressing the distal ureter to create the valve-like mechanism that prevents reflux.4 It is also well known that high intravesical pressure can, of itself, convert a previously anatomically competent ureterovesical junction to one that refluxes.5 The inherent high intravesical pressure during the period of small bladder enlargement after transplantation can, thereby, only enhance ureteral back pressure through an already anatomically incompetent ureterovesical junction, causing significant secondary hydroureteronephrosis, as occurred in our retrospective patient cohort, with possible impairment of renal function. The consequences of reflux with an abnormal, small bladder are, therefore, different and more serious than those with the milder forms of reflux sometimes
From the Departments of Surgery and Pediatrics, Stanford University School of Medicine, Palo Alto, California. Address reprint requests to Oscar Salvatierra, Jr, MD, Department of Surgery, Stanford University School of Medicine, Palo Alto, CA 94304.
© 1999 by Elsevier Science Inc. 655 Avenue of the Americas, New York, NY 10010
0041-1345/99/$–see front matter PII S0041-1345(99)00661-2
Transplantation Proceedings, 31, 3041–3042 (1999)
3041
3042
encountered in kidney recipients who have normal bladders.6 With regard to the actual management of the small, defunctionalized bladders, one needs to first accept the important fact that there is no perfect treatment.1 The risks of transplantation into a small, abnormal, non-neurogenic bladder should then be balanced against the risks and complications with a bowel-augmented urinary bladder as the receptacle for the transplant ureter.1 Most likely in this analysis, our reported implantation technique will be deemed the most appropriate procedure. In the unlikely event that this procedure were to fail, one can then resort to urinary bladder augmentation with bowel or ileal conduit diversion. The most important reasons for initial use of the native bladder and our implantation technique over other alternatives are the probable high likelihood of success, the restoration of normal urethral voiding function, and that most patients will be spared extensive additional procedures with their potential complications. In addition, the need for intermittent self-catheterization with an augmented urinary bladder or an appliance with an ileal conduit are avoided. This should also lead to a lesser likelihood of urinary infection. With these considerations in mind, our procedure would appear to have the potential to both greatly enhance patient quality of life and provide for significant cost-effectiveness over alternative approaches.1
SALVATIERRA
CONCLUSIONS
This novel technique for ureteral implantation successfully capitalizes on the regenerative potential of the bladder mucosa, resulting in a physiologic, anatomically natural, and very effective neosubmucosal tunnel. It appears to guarantee success against both ureteral reflux and obstruction, no matter how small the urinary bladder, and offers no hindrance to enlarging the bladder to near normal capacity post-transplantation. The implantation technique is simple and safe, and its use should eliminate the reluctance to use these bladders. Moreover, this procedure offers a major incentive for the successful rehabilitation of small, defunctionalized, non-neurogenic bladders after kidney transplantation.1 REFERENCES 1. Salvatierra O, Sarwal M, Alexander S, et al: Transplantation 68:731, 1999 2. Salvatierra O, Rigdon WO, Norris DM, et al: J Urol 191:615, 1969 3. Connolly JG, Morales A, Minnaker L, et al: Investigative Urol 8:481, 1971 4. Tanagho EA: Br J Urol 42:410, 1970 5. Atala A, Keating M: In Walsh PC, Retik AB, Vaughn ED, et al (eds.) Campbell’s Urology. Philadelphia, PA: Saunders; 1998, p 1859 6. Salvatierra O: Pediatr Transplant 3:171, 1999