Kidney transplantation in children with urinary diversion or bladder augmentation

Surgical considerations in paediatric kidney transplantation: an update

Background

Kidney transplantation has established itself as the most appropriate mode of renal replacement therapy for the majority with end-stage kidney disease. Although at present this is applicable for children as well as adults, a few decades back kidney transplantation was not considered a first-line option in children. This was due to inferior outcomes following transplantation in this age group compared to that of adults. These poor results were attributed to challenges in paediatric transplantation such as the shortage of suitable donors, technical difficulties in performing a sound vascular anastomosis and the adverse effects of immunosuppressive medication on growth and development. However, current patient and graft-centred outcomes after paediatric transplantation equal or surpass that of adults. The advances in evaluation and management of specific surgical concerns in children who undergo transplantation, such as pre-transplant native nephrectomy, correction of congenital anomalies of the urinary tract, placement of an adult-sized kidney in a small child and minimizing the risk of allograft thrombosis, have contributed immensely for these remarkable outcomes.

Conclusions

In this review, we aim to discuss surgical factors that can be considered unique for children undergoing kidney transplantation. We believe that an updated knowledge on these issues will be invaluable for transplant clinicians, who are dealing with paediatric kidney transplantation.

Renal Transplant in Abnormal Bladder: Treatment Options and Their Effects on Graft Outcome

OBJECTIVES

Correction of structural urologic disorders and optimization of emptying and storage function of the bladder should be achieved before renal transplant in patients with abnormal urinary bladders to protect the new transplanted kidney. The aim of this study was to determine the outcomes of renal transplant among the differently treated abnormal bladder patients.

MATERIALS AND METHODS

This was a retrospective study of 30 renal transplant recipients with abnormal bladders who were divided into 2 groups based on abnormal bladder management. Group A included 12 patients who required surgical procedures for their bladder, including 6 with augmentation cystoplasty, 1 with Mitrofanoff procedure, 2 with ileal conduit, 1 with vesicostomy, and 2 who required artificial urinary sphincter. Group B included 18 patients who were treated with oral anticholinergics or beta-3 sympathomimetic drugs, clean intermittent catheterization, suprapubic catheterization, or a combination of these options. Graft function, survival, and complications were compared between both groups.

RESULTS

Mean estimated glomerular filtration rates at 1, 3, and 5 years were higher in group A than in group B but not statistically significant. We also found no significant differences in graft survival between the 2 groups. Among all postoperative complications, only incidence of wound infection was significantly higher in group A than in group B (33% vs 5%; P = .04).

CONCLUSIONS

The options of abnormal bladder treatment (either by surgical procedures or other methods of treatment) did not have an impact on graft outcome after renal transplant as long as a safe and suitable bladder was achieved.

The standard of urological consultation of patients qualified for renal transplant - a review

Urological consultation is an important step in the procedure of a patient's preparation before placing him/her on a waiting list for a renal transplant. Urological work-up aims to diagnose, treat, and optimize any preexisting urological disease. In the present paper we present the review of the literature together with the authors' conclusions based on literature and their experience. There is not enough data in current literature and urology manuals on the adequate sequence of the urological management with patients qualified for renal transplant and the literature needs an update. This study presents the crucial steps of the qualification and emphasizes the urge for a more standardized urological approach in patients qualified for a kidney transplantation.

Long-term outcome of kidney transplantation in patients with a urinary conduit: a case-control study

PURPOSE

To study the short- and long-term outcomes of kidney transplantation in patients with a bladder augmentation or urinary diversion compared to patients with a kidney transplantation in a normal functional bladder.

PATIENTS AND METHODS

Between January 2000 and March 2011, 13 patients received 16 grafts into a reconstructed urinary tract. We performed a retrospective case-control study and matched each patient to 4 controls for donor and recipient gender and year of transplantation.

RESULTS

Short- and long-term complications of kidney transplantation occurred in 12 patients, varying from urinary tract infections to medical hospitalization with or without surgical or radiological intervention. In 5 patients, a percutaneous nephrostomy (PCN) was placed followed by surgical re-intervention. In three patients, the grafts failed as a result of chronic rejection and were re-transplanted. There was no graft loss as a result of surgical complications or the reconstructed urinary tract. One-year patient and graft survival was 100 %. After five years, all patients were alive and seven of nine grafts (77.8 %) were functioning. Mean follow-up time was 4.3 years. Among the controls, 55 grafts were transplanted in 52 patients. Ten patients received a PCN. Five patients needed surgical re-intervention. In three patients, transplantectomy was performed for ongoing rejection. Three patients were re-transplanted. One patient had a failing graft 7.5 years post-transplantation and became dialysis dependent.

CONCLUSION

Kidney transplantation in patients with a reconstructed urinary tract has an increased complication rate. Nevertheless, the long-term results are comparable to patients with a normal urinary bladder.

The effect of manipulation of silk scaffold fabrication parameters on matrix performance in a murine model of bladder augmentation

Autologous gastrointestinal segments are utilized as the primary option for bladder reconstructive procedures despite their inherent morbidity and significant complication rate. Multi-laminate biomaterials derived from Bombyx mori silk fibroin and prepared from a gel spinning process may serve as a superior alternative for bladder tissue engineering due to their robust mechanical properties, biocompatibility, and processing plasticity. In the present study, we sought to determine the impact of variations in winding (axial slew rate: 2 and 40 mm/s) and post-winding (methanol and lyophilization) fabrication parameters on the in vivo performance of gel spun silk scaffolds in a murine model of bladder augmentation. Three silk matrix groups with distinct structural and mechanical properties were investigated following 10 weeks of implantation including our original prototype previously shown to support bladder regeneration, Group 1 (2 mm/s, methanol) as well as Group 2 (40 mm/s, methanol) and Group 3 (40 mm/s, lyophilization) configurations. Non surgical animals were assessed in parallel as controls. Quantification of residual scaffold area demonstrated that while Group 1 and 2 scaffolds were largely intact, processing parameters utilized for Group 3 led to significantly higher degrees of scaffold degradation in comparison to Group 1. Histological (hematoxylin and eosin, masson's trichrome) and immunohistochemical (IHC) analyses showed comparable extents of smooth muscle regeneration and contractile protein (α-smooth muscle actin and SM22α) expression within the original defect site throughout all matrix groups similar to controls. Parallel evaluations demonstrated transitional urothelial formation with prominent uroplakin and p63 protein expression supported by Group 1 and 3 scaffolds, while Group 2 variants supported a thin, immature epithelium composed primarily of uroplakin-negative, p63-positive basal cells. Voided stain on paper analysis revealed similar voiding patterns between all matrix groups; however Group 2 animals displayed substantially lower voided volumes with increased frequency in comparison to controls. In addition, cystometric assessments revealed all matrix groups supported comparable degrees of bladder compliance similar to control levels. The results of this study demonstrate that selective alterations in winding and post-winding fabrication parameters can enhance the degradation rate of gel spun silk scaffolds in vivo while preserving their ability to support bladder tissue regeneration and function.

Evaluation of gel spun silk-based biomaterials in a murine model of bladder augmentation

Currently, gastrointestinal segments are considered the gold standard for bladder reconstructive procedures. However, significant complications including chronic urinary tract infection, metabolic abnormalities, urinary stone formation, bowel dysfunction, and secondary malignancies are associated with this approach. Biomaterials derived from silk fibroin may represent a superior alternative due their robust mechanical properties, biodegradable features, and processing plasticity. In the present study, we evaluated the efficacy of a gel spun silk-based matrix for bladder augmentation in a murine model. Over the course of 70 d implantation period, H&E and Masson's trichrome (MTS) analysis revealed that silk matrices were capable of supporting both urothelial and smooth muscle regeneration at the defect site. Prominent uroplakin and contractile protein expression (α-actin, calponin, and SM22α) was evident by immunohistochemical analysis demonstrating maturation of the reconstituted bladder wall compartments. Gel spun silk matrices also elicited a minimal acute inflammatory reaction following 70 d of bladder integration, in contrast to parallel assessments of small intestinal submucosa (SIS) and poly-glycolic acid (PGA) matrices which routinely promoted evidence of fibrosis and chronic inflammatory responses. Voided stain on paper analysis revealed that silk augmented animals displayed similar voiding patterns in comparison to non surgical controls by 42 d of implantation. In addition, cystometric evaluations of augmented bladders at 70 d post-op demonstrated that silk scaffolds supported significant increases in bladder capacity and voided volume while maintaining similar degrees of compliance relative to the control group. These results provide evidence for the utility of gel spun silk-based matrices for functional bladder tissue engineering applications.

Treatment strategies to minimize or prevent chronic allograft dysfunction in pediatric renal transplant recipients: an overview

Long-term allograft survival poses a major problem in pediatric renal transplantation, with allograft nephropathy being the principal cause of graft failure after the first post-transplant year. The mechanisms of nephron loss resulting in graft dysfunction are multiple, comprising both immunologic factors such as acute and chronic antibody- or T-cell-mediated rejection and non-immunologic components. The latter include peri-transplant injuries and renovascular lesions (renal artery stenosis, thrombosis) as well as cardiovascular risk factors such as arterial hypertension and hyperlipidemia. Another relevant issue leading to progressive nephron loss and declining kidney transplant function is acute and chronic nephrotoxicity induced by the calcineurin inhibitors (CNIs) ciclosporin (cyclosporine microemulsion) and tacrolimus. Furthermore, the presence of an abnormal lower urinary tract as well as bacterial (recurrent pyelonephritis) and viral (cytomegalovirus [CMV], polyomavirus [BK virus; BKV]) infections are crucial factors involved in the incidence of chronic allograft dysfunction and graft failure. Renovascular lesions and lower urinary tract obstruction are typical indicators for surgical intervention. The aim of treatment in pediatric patients with renal failure secondary to a dysfunctional lower urinary tract is to create a sterile, continent, and nonrefluxive reservoir. Surgical techniques such as bladder augmentation and the introduction of intermittent catheterization and anticholinergic therapy have significantly improved graft outcome. Arterial hypertension, another factor responsible for graft function deterioration in pediatric renal transplant recipients, is controlled preferably by the use of angiotensin converting enzyme (ACE) inhibitors or angiotensin II receptor antagonists, which are known to possess nephroprotective properties in addition to their potent antihypertensive effects. Although treatment of subclinical rejection with augmented immunosuppression has been associated with better graft survival, an increase of the immunosuppressive level to avoid subclinical rejection should be weighed against the risk of infection. The majority of viral infections affecting kidney allografts are caused by CMV and BKV. Antiviral CMV prophylaxis or pre-emptive therapy with ganciclovir has been shown to have beneficial effects in the pediatric renal transplant population. Treatment of BKV-induced nephropathy is based on reduction of the immunosuppressant therapy, although specific antiviral agents such as cidofovir and leflunomide are known to inhibit BKV. However, cidofovir itself is nephrotoxic and should therefore be administered cautiously to pediatric renal transplant patients. Since CNIs are likewise known for their nephrotoxic effects, especially with long-term use, alteration of the immunosuppressant regimen is necessary in case of deteriorating graft function due to CNI-induced histopathologic changes. Complete CNI avoidance seems inappropriate because, in this situation in pediatric renal transplant recipients, other relatively potent immunosuppressant agents such as lymphocyte-depleting antibodies, which are frequently accompanied by a higher incidence of infections, are needed for rejection prophylaxis. CNI withdrawal and switching of the immunosuppressant regimen from CNI therapy to sirolimus may be an option for some pediatric renal transplant patients with less advanced graft function deterioration. Nevertheless, potential adverse events such as aggravation of proteinuria, hyperlipidemia, myelosuppression, and hypergonadotropic hypogonadism have to be considered, and controlled studies are lacking. At present, an immunosuppressant maintenance therapy composed of low-dose tacrolimus or ciclosporin (CNI minimization) and mycophenolate mofetil with low-dose corticosteroids appears to be the most promising strategy to adopt in pediatric renal transplant recipients at low or normal immunologic risk.

[Renal transplantation and urinary diversion]

For patients with end-stage renal disease and dysfunctional or absent lower urinary tract, complex therapeutic strategies are necessary combining kidney transplantation and - if possible - continent urinary diversion. In this concept urinary diversion is the first step in a two-stage procedure followed by renal transplantation. Meticulous preoperative diagnostics, careful patient selection and life-long close surveillance are critical for the success of this concept. The published data concerning long-term graft and patient survival are promising.

Partial bladder transplantation with en bloc kidney transplant--the first case report of a 'bladder patch technique' in a human

Transplantation of the urinary bladder has not been reported in humans. We transplanted a portion of the donor bladder with an en bloc kidney graft in a 12-month-old girl. The child had a congenital hypoplastic single kidney with an ectopic ureteral opening into the vagina. Her native bladder was extremely small. Bilateral kidneys were transplanted en bloc with their ureters connected to a patch of the donor bladder, which encompassed the bilateral ureterovesical junctions (UVJs) (bladder patch technique). Approximately one-third of the donor bladder wall was used. The bladder patch reperfused well via blood supply from the ureters. Posttransplant cystoscopy with retrograde cystogram revealed a viable transplanted bladder with normal emptying of transplanted ureters. No reflux across the donor UVJs was seen in a voiding cystourethrogram. The child is doing well with normal renal function at 18-month follow-up.

Renal transplantation or bladder augmentation first? A comparison of complications and outcomes in children

OBJECTIVE

To identify whether the order of performing transplant and bladder reconstruction operations in children who need both operations affects outcome of either operation.

PATIENTS AND METHODS

A retrospective case note review was performed of children identified from our database, who had undergone both renal transplantation and bladder augmentation between 1990 and 2005.

RESULTS

In all, 18 renal transplants (eight live-related) were performed in 16 children with 10 transplants done after bladder augmentation and eight transplants done before augmentation. The median age at transplantation was 7.5 years and at augmentation was 7.0 years. The median interval between the operations was 33.5 months and the median follow-up was 58.4 months after transplantation. Outcomes were compared between the two groups of patients: those who received their transplantation before bladder augmentation, and those who were transplanted after bladder augmentation. There was no difference between these groups in: the pre- transplant estimated glomerular filtration rate, inpatient stay after transplantation or after augmentation, and incidence of urinary tract infection in the 3 months after renal transplantation or after bladder augmentation. There was no statistical difference in renal allograft loss with one graft failure in the group who were augmented first, and four graft failures in the group who were transplanted first. However, it is of note that the single graft failure in the patient augmented first was due to renal artery thrombosis on the first day related to a double arterial anastomosis, whilst in the other group, three of the graft failures were in transplants that had initially been drained by ureterostomy. Three patients in the group transplanted first developed significant ureteric pathology, of which one developed graft failure.

CONCLUSION

Bladder reconstruction can be performed safely before transplantation; it does not increase complications and might better protect the renal graft and specifically the transplant ureter.

Increased urologic complications in children after kidney transplants for obstructive and reflux uropathy

In the cyclosporine era, reports on pediatric kidney transplant (KTx) patients with obstructive and reflux uropathy are limited by small numbers, short follow-up, and/or lack of control groups. Our single-center study evaluated long-term outcomes (patient and graft survival, urinary tract infections [UTIs], urologic complications) in a large cohort of KTx recipients (<20 years old). We matched our 117 study patients with obstructive and reflux uropathy with 117 controls whose KTx was needed for other reasons; all 234 underwent their KTx between April 25, 1984, and October 23, 2002. The mean age was 8.0 +/- 6.2 years; mean follow-up, 133 +/- 67 months. The urologic complication rate was higher in study patients (43%) than in controls (11%) (p < 0.0001), as was the UTI rate (45% vs. 2%; p < 0.0001). The metabolic acidosis and UTI rates were higher in study patients who did (vs. did not) undergo bladder augmentation (p < 0.0001). We found no significant difference between study patients and controls in patient or graft survival, acute or chronic rejection, or mean estimated glomerular filtration rates. Unique to our study is the finding of higher metabolic acidosis and UTI rates in study patients who underwent bladder augmentation.

Kidney transplantation in abnormal bladder

Structural urologic abnormalities resulting in dysfunctional lower urinary tract leading to end stage renal disease may constitute 15% patients in the adult population and up to 20-30% in the pediatric population. A patient with an abnormal bladder, who is approaching end stage renal disease, needs careful evaluation of the lower urinary tract to plan the most satisfactory technical approach to the transplant procedure. Past experience of different authors can give an insight into the management and outcome of these patients. This review revisits the current literature available on transplantation in abnormal bladder and summarizes the clinical approach towards handling this group of difficult transplant patients. We add on our experience as we discuss the various issues. The outcome of renal transplant in abnormal bladder is not adversely affected when done in a reconstructed bladder. Correct preoperative evaluation, certain technical modification during transplant and postoperative care is mandatory to avoid complications. Knowledge of the abnormal bladder should allow successful transplantation with good outcome.

Kidney transplants in patients with bladder augmentation: correlation and evolution

OBJECTIVE

To review the literature, analyse the evolution of kidney transplants (KT) in patients with bladder augmentation (BA) and investigate the relation between BA and KT.

MATERIALS AND METHODS

Six patients with a history of severe lower urinary tract dysfunction and BA, received a KT at our Unit between 1993 and 2003. Three had moderate renal failure at the moment of the BA. The remaining three had end stage renal failure.

RESULTS

With a follow-up of 7 years (mean) we have a patient survival of 100% and a graft survival of 83%. No complications occurred between the BA and the KT. The few KT complications were not related to BA.

CONCLUSION

When a bladder dysfunction is present, it should be treated before KT. In noncompliant bladders, BA is the best treatment. This can be done to try to avoid end stage renal failure or only to prepare the lower urinary tract for reception of the transplant. The presence of a BA did not worsen the evolution of the KT.

Renal transplantation in children with posterior urethral valves

The objective of this study was to analyze whether renal transplantation (RT) in children with posterior urethral valves (PUV) constitutes a special group with respect to groups with different etiologies of end-stage renal disease (ESRD). Between 1979 and 2004, 22 RT were performed in 19 children with PUV. The median age at RT was 10 years (range: 1.3-17). Immunosuppression was provided by triple therapy and polyclonal/monoclonal antibodies. This group was compared with the two control groups: (1) glomerulopathy (n=62) and (2) pyelonephritis/dysplasia (n=42) without lower urinary tract disease, transplanted in the same period. Ten graft losses occurred in 22 transplants: thrombosis (2), acute rejection (3), chronic graft nephropathy (2), and death of patients (3) with a functioning graft in the 1st postoperative month. We did not find significant differences versus the control group in renal function or probability of graft or patient survival at 1, 5, and 10 years. We observed a greater risk of urological complication in patients with PUV. RT with PUV constitutes a special group due to the compulsory young age and the need for careful and complex medicosurgical management; nevertheless, the results achieved were similar to those obtained in our general RT population.