Pyelonephritis following pediatric renal transplant: increased incidence with vesicoureteral reflux

Role of vesicoureteral reflux on pediatric kidney allograft function

BACKGROUND

Vesicoureteral reflux (VUR) is a common urologic complication of pediatric kidney transplant, though there is little data on the effect of VUR on histologic graft changes or graft survival.

METHODS

All pediatric patients who received a kidney transplant from 2007 to 2020 were selected for retrospective chart review. All participants underwent a voiding cystourethrogram (VCUG) at a 6-month post-transplant. Patients were then categorized into two groups based on vesicoureteral reflux grade: no/low-grade VUR (grades 0-2) and high-grade VUR (grades 3-5). Outcomes collected included graft failure rates, graft function, urinary tract infections (UTIs), proteinuria, and Banff scores at 3- and 12-month post-transplant surveillance kidney biopsies.

RESULTS

There were 74 pediatric patients who received a kidney transplant in the designated time-period, and of those 39 had no/low-grade VUR and 35 had high-grade VUR. There was no difference in graft failure among the two groups over time when stratified for age (p = 0.389, CI 0.53-5.08). Patients with high grade VUR had a higher risk of UTI development overall (RR 1.89, 95%CI 1-3.6, p = 0.041), mostly accounted for from increased development of febrile UTI (RR 1.66, 95%CI 1.1-2.6, p = 0.038).

CONCLUSIONS

Unselected pediatric kidney transplant recipients with high-grade vesicoureteral reflux on VCUG at a 6-month post-kidney transplant are more likely to have febrile UTI compared to those in the low-grade VUR group. There is no difference in graft survival among the two groups.

Current management of symptomatic vesicoureteral reflux in pediatric kidney transplantation-A European survey among surgical transplant professionals

BACKGROUND

Vesicoureteral reflux (VUR) is common in children and adolescents undergoing kidney transplantation (KTx) and may adversely affect allograft kidney function.

METHODS

To explore the current management of symptomatic native and allograft VUR in pediatric KTx recipients, an online survey was distributed to European surgical transplant professionals.

RESULTS

Surgeons from 40 pediatric KTx centers in 18 countries participated in this survey. Symptomatic native kidney VUR was treated before or during KTx by 68% of the centers (all/selected patients: 33%/67%; before/during KTx: 89%/11%), with a preference for endoscopic treatment (59%). At KTx, 90% favored an anti-reflux ureteral reimplantation procedure (extravesical/transvesical approach: 92%/8%; preferred extravesical technique: Lich-Gregoir [85%]). Management strategies for symptomatic allograft VUR included surgical repair (90%), continuous antibiotic prophylaxis (51%), bladder training (49%), or noninterventional surveillance (21%). Redo ureteral implantation and endoscopic intervention for allograft VUR were equally reported (51%/49%).

CONCLUSIONS

This survey shows uniformity in some surgical aspects of the pediatric KTx procedure. However, with regard to VUR, there is a significant variation in practice patterns that need to be addressed by future well-designed and prospective studies. In this way, more robust data could be translated into consensus guidelines for a more standardized and evidence-based management of this common condition in pediatric KTx.

Vesico-ureteric reflux in children and young people undergoing kidney transplantation

Vesico-ureteric reflux (VUR) into transplanted kidneys in children and young people is a common occurrence, found in 19 to 60% of those who had an anti-reflux procedure and up to 79% in the absence of such a procedure. While VUR is unlikely to be of concern without evidence of symptomatic urinary tract infections, less certainty exists regarding outcomes when the VUR is associated with urinary tract infection (UTI) and transplant pyelonephritis. Issues explored will include additional risk factors that might predispose to UTI, any effect of pyelonephritis on acute and long-term kidney allograft function and practical strategies that may reduce the prevalence of infection.

Revision ureteroneocystostomy in pediatric renal transplant patients for symptomatic vesicoureteral reflux and its effect on recurrent hospitalizations

BACKGROUND

Nearly 13,000 pediatric renal transplantations have been performed since 1987 with improving overall mortality and morbidity; however, graft infection remains a significant post-transplant concern. Recurrent urinary tract infections in pediatric patients with vesicoureteral reflux into their renal transplant can result in graft dysfunction, increased hospital cost, and impaired social and cognitive development due to time spent hospitalized.

OBJECTIVE

To evaluate the effect of revision ureteroneocystostomy on pediatric renal transplant patients with symptomatic vesicoureteral reflux in reducing hospitalizations and recurrent urinary tract infections.

METHODS

We retrospectively reviewed pediatric patients from 2002 through 2021 who underwent renal transplantation and required revision ureteroneocystostomy due to symptomatic vesicoureteral reflux. We analyzed the differences in days hospitalized, days hospitalized due to urinary tract infection, and treated urinary tract infections prior to and after revision ureteroneocystostomy.

RESULTS

Ten patients requiring revision ureteroneocystostomy secondary to symptomatic vesicoureteral reflux were identified. There was no difference in the observation time between transplant to revision, and revision to last follow up (2.3 years (IQR 1.3-6.5) vs 1.7 years (IQR 1-6.7), p = 0.4446). Overall, there was a significant decrease in the total number of hospitalization days (21.5 days (IQR 3-43) vs 5.5 days (IQR 0-9), p = 0.006), total number of hospitalization days related to urinary tract infection (14.5 days (IQR 3-28) vs 0 days (IQR 0-3), p = 0.008) and treated urinary tract infections (3.5 (IQR 3-6) vs 1 (IQR 0-2), p = 0.019) following revision ureteroneocystostomy. The rate of hospitalization days for urinary tract infection was also significantly decreased following revision ureteroneocystostomy (7.15 per/year (IQR 0.4-11.75) vs 0 per/year (IQR 0-0.8), p = 0.008).

DISCUSSION

Symptomatic vesicoureteral reflux in pediatric transplant patients is difficult to manage and some patients will ultimately require surgery. There have been previous studies on the success of revision ureteroneocystostomy in treating reflux but no data on the reduction in hospitalizations associated with recurrent infections following the procedure. Limitations of this study are the small cohort size, retrospective nature, multi-surgeon study, and inherent selection bias due to evaluation of only surgical patients.

CONCLUSION

Revision ureteroneocystostomy can limit the negative consequences of recurrent graft infections with reduction in hospitalization days and improved hospitalization rates due to urinary tract infections. The reduction in hospitalizations can greatly improve the cost of care along with quality of life for transplant patients and should be strongly considered in children with symptomatic vesicoureteral reflux who have failed conservative therapy.

Emergency Department Utilization and Serious Bacterial Infection Rates in Children With Renal Transplants

OBJECTIVES

Emergency department (ED) visits by children with solid organ transplants have increased significantly. Our objectives were to describe the common complaints, diagnosis, types, and rates of serious bacterial infection (SBI) in children with renal transplant (RT) who present to the hospital.

METHODS

We conducted a retrospective study from 2012 to 2016 of RT children up to 18 years who presented to the ED or were directly admitted. We excluded patients who presented for a procedure. We collected demographics, transplant type, immunosuppressive data, chief complaints, diagnostic testing with results, interventions performed, and final diagnosis.

RESULTS

We analyzed 131 visits in 29 patients during the study period. Most common chief complaints were infectious (34.4%) and gastrointestinal (26%). Infection was proven in 42.0% of visits with only 3.1% being organ rejection. Serious bacterial infection was diagnosed in 34 visits (26.0%) with urinary tract infection (UTI) being the most common (20.6%). Of the 33 visits for fever, SBI occurred in 16 (48.5%) patients with the most common SBI being UTI 10 (30.3%). Bacteremia occurred in 1 patient and hypotension in 4 patients. Antibiotic administration was the most common intervention performed (78; 59.5%). Significant interventions were uncommon (2 patients). Logistic regression revealed no factors to be associated with SBI.

CONCLUSIONS

Our cohort of children with RT presented most commonly with infections to the hospital with UTI being the most common SBI. Bacteremia and significant interventions were rare. Future studies are needed to identify subgroups of low-risk pediatric RT patients who can possibly be safely discharged home from the ED.

Pediatric kidney transplant recipients with and without underlying structural kidney disease have a comparable risk of hospitalization associated with urinary tract infections

INTRODUCTION

Urinary tract infections (UTIs) are a common and potentially serious kidney transplant complication. Pediatric kidney transplants are potentially at increased risk for UTIs when structural kidney disease is the underlying end-stage kidney disease (ESKD) etiology. The objective of this manuscript is to determine if children with structural kidney disorders are more prone to UTIs post kidney transplant.

MATERIALS AND METHODS

Hospitalizations for pediatric kidney transplant recipients were retrospectively reviewed over a 4-year period for UTIs in the diagnostic codes. The patient's age, sex, graft age, underlying diagnosis for cause of ESKD, symptoms at presentation, urinalysis results, and urine culture results were recorded. UTI rates, febrile UTI rates, and UTI rates in the 1st year post-transplant were compared between children with ESKD due to structural vs. non-structural kidney disease.

RESULTS

Overall, 62 of 145 pediatric patients with kidney transplants accounted for 182 hospitalizations for kidney transplant complications over the 4-year study period. UTIs were components of 34% of the hospitalizations. Overall, UTI rates, febrile UTI rates, and UTI rates for the 1st year post kidney transplant were comparable for children with vs. without structural ESKD etiologies.

CONCLUSION

Urinary tract infections are frequent components of hospitalizations for pediatric kidney transplant recipients. Children with and without structural kidney disease as an ESKD etiology have similar UTI rates indicating that UTI susceptibility is primarily due to the transplant process and/or medication regimens. UTIs represent a potentially modifiable risk factor for pediatric kidney transplant complications.

A systematic review of outcomes of Deflux® treatment for vesicoureteral reflux following pediatric renal transplantation

INTRODUCTION

Vesicoureteral reflux (VUR) after renal transplant in the pediatric population may be associated with an increased incidence of urinary tract infection (UTIs) leading to increased morbidity, including graft dysfunction and graft loss. The non-orthotopic location of the transplanted ureter, and lack of submucosal tunnel may pose challenges in correcting the VUR using endoscopic injection techniques. Herein we report the results of a systematic review evaluating the outcomes of endoscopic treatment of VUR using Deflux® in this population.

METHODS

Pubmed and Embase databases were searched from October 2001 to April 2019. Full-text English articles involving patients less than 18 years old at the time of transplant, with a diagnosis of VUR post-transplantation, who underwent Deflux® treatment were included. Figure 1 outlines our PRISMA-compliant search strategy.

RESULTS

We found 6 eligible studies describing Deflux® treatment outcomes in 67 pediatric patients with post-transplant VUR where voiding cystourethrogram (VCUG) confirmed the diagnosis and resolution of VUR. The mean success rate was 36.8%. Ureteral obstruction occurred in 7/67 cases (10.4%). In all these 7 cases of obstruction, ureteric stenting was the initial management, but was only successful in 1 patient. Open ureteroneocystostomy (UNC) was performed in 4/7 cases, while 2/7 were managed expectantly (unknown outcomes). Persistent VUR with UTI despite Deflux® were reported in 20 out of 67 cases. Of these, 7 were managed with prophylactic antibiotics, and 13 with UNC. Success rates were consistently low for UNC after failed Deflux® in comparison to redo UNC in transplant ureters without prior injection.

CONCLUSION

Low success rates are seen following injection techniques for VUR after pediatric renal transplant. Although an appealing option, Deflux® may prove counterintuitive due to the high rate of obstruction and suboptimal results if open reimplantation is required. A multi-institutional prospective study with a larger population size may further elucidate these results.

Increasing bladder capacity and vesicoureteral reflux in pediatric kidney transplant patients

OBJECTIVES

To investigate the frequency of vesicoureteral reflux, and the relationship of pretransplant decreased bladder capacity and post-transplant vesicoureteral reflux in children undergoing kidney transplantation.

METHODS

A voiding cystourethrography was carried out in 172 pediatric kidney transplantation recipients before, and 4 months after, transplantation to evaluate bladder capacity and vesicoureteral reflux. The correlation of post-transplant vesicoureteral reflux with pretransplant bladder capacity, vesicoureteral reflux in the native kidney and the method of ureteral reimplantation (intravesical/extravesical) was analyzed. Atrophic bladder was defined as having ≤50% functional bladder capacity (age in years + 2) × 25 (mL) or ≤150 mL in patients aged >10 years.

RESULTS

Bladder capacity increased remarkably after transplantation in both post-transplant vesicoureteral reflux- group (from 180 to 253 mL) and vesicoureteral reflux+ group (from 82 to 171 mL). Voiding cystourethrography showed vesicoureteral reflux in 12 cases of kidney transplantation (7%; grade 1: 2, grade 2: 3, grade 3: 7). Pretransplant atrophic bladder was an independent risk factor of post-transplant vesicoureteral reflux (P = 0.004, hazard ratio 9.5). There was no difference in renal function between the vesicoureteral reflux- group and vesicoureteral reflux+ group at 4 months to 5 years post-transplantation.

CONCLUSIONS

Pretransplant atrophic bladder is a risk factor of post-transplant vesicoureteral reflux in pediatric patients. However, bladder capacity can remarkably increase after transplantation, and kidney function in the post-transplant vesicoureteral reflux+ group is stable.

When does vesicoureteral reflux in pediatric kidney transplant patients need treatment?

PURPOSE

The treatment of VUR in children with UTI has changed significantly, due to studies showing that antibiotic prophylaxis does not decrease renal scarring. As children with kidney transplants are at higher risk for UTI, we investigated if select patients with renal transplant VUR could be managed without surgery.

MATERIALS AND METHODS

A total of 18 patients with VUR into their renal grafts were identified, and 319 patients underwent transplantation from 2006 to 2016. The cause for the detection of the VUR, treatment, and graft function was reviewed.

RESULTS

Six boys and 12 girls were identified, 13 of whom had grade 3 or 4 VUR into the renal graft. Nine patients presented with hydronephrosis or abnormal renal biopsy: eight were successfully managed with antibiotic prophylaxis and bladder training, one developed UTI and underwent Dx/HA subureteric injection. Nine patients presented with recurrent febrile UTI, only one was successfully managed without surgery. Only 2 of 9 (22%) patients who underwent Dx/HA injection had resolution of their reflux. Of the remaining seven, five required open ureteral reimplantation (two for obstruction), one lost the graft due to rejection, and one had significant hydronephrosis. eGFR was similar between the hydronephrosis, UTI, and abnormal renal biopsy groups at all times.

CONCLUSION

Patients with transplant VUR and recurrent febrile UTI are more likely to require surgical therapy, but the complication and failure rate for Dx/HA injection is significant. Patients with transplant VUR without febrile UTI can be successfully managed with bladder training and temporary antibiotic prophylaxis.

Comparison of Surgical Correction Techniques for Post-Renal Transplantation Vesicoureteral Reflux

BACKGROUND

Symptomatic urinary tract infection (UTI) after renal transplantation (RT) is an important morbidity in transplant recipients and may cause pyelonephritis and sepsis. Surgical correction of high-grade vesicoureteral reflux (VUR) after RT is suggested, performing ureteral reimplantation or pyelo-ureteral/uretero-ureteral anastomosis. Recently, extravesical seromuscular tunnel lengthening techniques have been reported with favorable results and low complication rates.

METHODS

We retrospectively reviewed the charts of 38 patients with post-transplantation VUR who underwent reflux correction surgery. Patient characteristics were analyzed to compare our extravesical seromuscular tunnel lengthening technique with uretero-ureteral and pyelo-ureteral anastomosis techniques.

RESULTS

Twenty patients were treated with the extravesical approach (group I) and 18 patients by pyelo-ureteral or uretero-ureteral anastomosis with the use of native ureter (group II). Mean operative time was significantly shorter in group I than in group II (64.8 vs 110.1 min; P < .05), and mean duration of hospital stay after the operation also was shorter in group I (1.5 vs 5.1 d; P < .05). We determined persistent VUR in postoperative voiding cystouretrography in 2 patients (10%) in group I, but there was regression in VUR grades of all of the patients. There was no significant difference in postoperative number of UTI episodes and serum creatinine levels between the 2 groups.

CONCLUSIONS

Extravesical seromuscular tunnel lengthening is an effective and safe technique for post-transplantation VUR management.

Kidney transplant in pediatric patients with severe bladder pathology

The aim of the current study was to compare results in pediatric renal transplantation of patients with and without SBP. Between 2001 and 2013, a total of 168 kidney transplants were performed at our center. A retrospective analysis was performed and recipients were divided into two groups: NB and SBP. Incidence of surgical complications after procedure, and graft and patient survival were evaluated. A total of 155 recipients (92%) with complete data were analyzed, and 13 recipients that had had previous bladder surgeries were excluded (11 with VUR surgery and two with previous kidney transplants), of the 155 recipients: 123 (79%) patients had NB, and 32 (21%) patients had SBP, with a median follow-up of 60 (1-137) and 52 (1-144) months, respectively. Among post-transplant complications, UTI (68.8% vs. 23%, p < 0.0001) and symptomatic VUR to the graft (40.6% vs. 7.3%, p < 0.0001) were significantly higher in the SBP group. There was no significant difference in overall graft and patient survival between groups. Renal transplantation is safe in pediatric recipients with SBP; however, urologic complications such as UTI and VUR were significantly higher in this group. Graft and patient survival was similar in SBP and NB groups.

National risk factors and estimated costs for redo ureteroneocystostomy after pediatric renal transplant

Approximately 800 pediatric renal transplants are performed annually in the United States. VUR or obstruction may cause graft failure requiring redo ureteroneocystostomy. We examined possible risk factors and cost using the PHIS national database. We examined the PHIS for 8.5 yr to determine the association between redo ureteroneocystostomy following pediatric renal transplant to demographics, comorbidities, GU conditions, insurance status, and hospital characteristics, and looked at relative costs using descriptive and comparative statistics. A total of 2390 pediatric renal transplants were identified, of which 69 (2.3%) underwent redo ureteroneocystostomy (median 11.6 months post-transplant). Risk factors for redo ureteroneocystostomy are younger age (p = 0.048), PUVs (p < 0.001), female gender (p = 0.005), race (p = 0.014), insurance type (p < 0.027), region (p = 0.045), and transplant surgery volume (p = 0.048). Redo ureteroneocystostomy after transplant does not significantly increase the overall cost of transplant (p = 0.175). We confirmed previous findings that younger age and PUVs increase the risk of post-transplant redo ureteroneocystostomy, with a five-yr plateau. We found an association with gender, race, insurance status, and hospital characteristics. Redo ureteroneocystostomy, which increases costs, does not statistically significantly increase overall cost of individual treatment in this database, although costs may be underreported.

A nipple-valve technique for ureteroneocystostomy in pediatric kidney transplantation

The ureteroneocystostomy in kidney transplantation can be performed with a variety of techniques. Over a 20-yr period, we utilized a technique of nipple-valve ureteroneocystostomy for the pediatric kidney transplants performed at our institution. The distal ureter is everted upon itself and anchored in place with four interrupted sutures to create a nipple valve, which is then inserted into the bladder and sewn mucosa-to-mucosa with the same sutures. The muscularis layer is closed around the ureter without tunneling and without routine ureteral stenting. After 109 transplants, patient survival was 97.2, 97.2, and 86.9% at one, five, and 10 yr, respectively. Graft survival was 91.7, 71.7, and 53.9% at one, five, and 10 yr, respectively. The most common cause of graft loss was acute or chronic rejection, seen in 75% of those experiencing graft loss. Two patients (1.8%) developed pyelonephritis in the transplanted kidney. Nipple-valve ureteroneocystostomy in pediatric kidney transplantation is a safe and simple method for performing the ureterovesical anastomosis with a low rate of pyelonephritis after transplantation.

Hydronephrosis in pediatric kidney transplant: clinical relevance to graft outcome

OBJECTIVE

To evaluate our pediatric renal transplant patient population at the Children's Hospital of Pittsburgh to better understand the clinical significance of hydronephrosis.

MATERIALS AND METHODS

We retrospectively reviewed records of patients who had received a renal transplant in 1998-2008. Exclusion criteria included multi-organ transplants and allograft failure within 3-months. We determined the incidence of hydronephrosis and compared serum creatinine, incidence of pyelonephritis, rejection and vesicoureteral reflux between the hydronephrotic and non-hydronephrotic cohorts. Data were analyzed using descriptive statistics, Student's t-test and Pearson Chi-Square test.

RESULTS

51 patients (35 male, 68.6%) were identified. The mean age at time of transplant was 8.7 ± 5.9 years and the mean follow-up period was 45.2 ± 45.4 months. Common causes of renal failure included posterior urethral valves, renal dysplasia, reflux and prune belly syndrome. Twenty-five (49%) patients developed hydronephrosis. This was associated with worsening renal function (p = 0.008). Hydronephrosis was also associated with pyelonephritis (p = 0.03) and male gender (p = 0.004). Age at transplant may be a predictor of pyelonephritis: median age of 10 patients with pyelonephritis was 4.6 years (range 0.6-19.9 years). Hydronephrotic cohort had increased rate of reflux and rejection; as not all patients underwent voiding cystourethrogram and/or allograft biopsy, this result was not significant.

CONCLUSIONS

Pediatric renal graft hydronephrosis was correlated with worsening renal function and increased incidence of pyelonephritis. More aggressive preoperative and postoperative urological testing and management should help preserve renal function.

Non-viral infections in children after renal transplantation

Renal transplantation has long been recognised as the gold standard treatment for children with end-stage renal failure. There has been an improvement over the years in patient and renal allograft survival because of improved immunosuppression, surgical techniques and living kidney donation. Despite reduced acute allograft rejection rates, non-viral infections continue to be a serious complication for paediatric renal transplant recipients (RTR). The risk of infections in RTR is determined by the pre-transplantation immunisation status, post-transplant exposure to potential pathogens and the amount of immunosuppression. The greatest risk of life-threatening and Cytomegalovirus infections is during the first 6 months post-transplant owing to a high immunosuppressive burden. The potential sources of bacterial infections are donor derived, transplant medium fluid, peritoneal and haemodialysis catheter and transplant ureteric stent. Urinary tract infections are frequent in patients with lower urinary tract dysfunction and can result in renal allograft damage. This review outlines the incidence, timing, risk factors, prevention and treatment of non-viral infections in paediatric RTR by critically reviewing current immunosuppressive regimens, their risk-benefit ratio in order to optimise renal allograft survival with reduced rates of rejection and infectious complications.

Low incidence of urinary tract infections following renal transplantation in children with bladder augmentation

PURPOSE

Children with end-stage renal disease and bladder dysfunction may require augmentation cystoplasty before kidney transplantation. Previous reports have suggested unacceptable urinary tract infection rates in these immunosuppressed patients. We reviewed our experience in this population.

MATERIALS AND METHODS

We retrospectively studied patients undergoing augmentation cystoplasty and subsequent renal transplantation by a single surgeon between 1989 and 2007. This cohort was compared with a control group on clean intermittent catheterization who had undergone transplantation without augmentation. Patient demographics, etiology of renal failure, surgical details, surgical/allograft outcomes and occurrence of urinary tract infection were analyzed.

RESULTS

The augmented group included 17 patients with a median age at reconstruction of 6.4 years. Stomach was used in 15 patients and colon in 2. Median time between reconstruction and transplantation was 1.2 years. Median followup after transplantation was 7.7 years. The control group included 17 patients with a median age at transplantation of 10.9 years. Median followup in the controls was 6.1 years. All ureteral reimplantations were antirefluxing. Patients on clean intermittent catheterization were maintained on oral antibiotic suppression and/or gentamicin bladder irrigations. In the augmented group 35 episodes of urinary tract infection were noted, and the number of documented infections per patient-year of followup was 0.22, compared to 32 episodes of urinary tract infection and 0.28 infections per patient-year of followup in the controls. No allograft was lost to infectious complications.

CONCLUSIONS

In our series there was no increase in urinary tract infection rate following renal transplantation in patients with augmented bladders compared to controls. This finding may be due to the use of gastric augmentation, antirefluxing reimplantation and gentamicin irrigations.

Endoscopic application of dextranomer/hyaluronic acid copolymer in the treatment of vesico-ureteric reflux after renal transplantation

OBJECTIVE

• To evaluate the success of endoscopic dextranomer/hyaluronic acid copolymer (DHAC) application in the treatment of patients with recurrent urinary tract infections (UTIs) and vesico-ureteric reflux (VUR) into the transplanted graft after renal transplantation.

PATIENTS AND METHODS

• Between January 2008 and April 2009, 19 patients with recurrent UTIs presented VUR proven by voiding cystourethrography. • To correct VUR of the transplanted ureter, DHAC was injected endoscopically using hydrodistention technique. • Pre- and postoperative serum creatinine levels, the number of pre- and postoperative UTIs, postoperative complications and reflux resolution rate were recorded. The mean follow-up was 6.5 months.

RESULTS

• The average number of UTIs was reduced significantly from 4.89 (range 2-14) to 1.31 (range 0-4) on pre- and postoperative follow-up, respectively, of 6 months (P < 0.001). The success rate increased from 57.9% after the first injection to 78.9% after the second injection. • The remaining four patients with residual VUR received long-term low dose antibiotic prophylaxis. In total, two (10.5%) patients developed increasing creatinine levels postoperatively as a result of distal ureteral obstruction, and temporary urinary drainage was necessary in both patients.

CONCLUSIONS

• DHAC appears to be an efficient and minimal invasive method for treating VUR after renal transplantation with respect to short-term success. • Further investigation with a larger group of patients and longer follow-up is needed to evaluate the prolonged effect, as well as any potential side effects.

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.

Urinary tract infections in children after renal transplantation

Urinary tract infections (UTI) after pediatric kidney transplantation (KTX) are an important clinical problem and occur in 15-33% of patients. Febrile UTI, whether occurring in the transplanted kidney or the native kidney, should be differentiated from afebrile UTI. The latter may cause significant morbidity and is usually associated with acute graft dysfunction. Risk factors for (febrile) UTI include anatomical, functional, and demographic factors as well as baseline immunosuppression and foreign material, such as catheters and stents. Meticulous surveillance, diagnosis, and treatment of UTI is important to minimize acute morbidity and compromise of long-term graft function. In febrile UTI, parenteral antibiotics are usually indicated, although controlled data are not available. As most data concerning UTI have been accumulated retrospectively, future prospective studies have to be performed to clarify pathogenetic mechanisms and risk factors, improve prophylaxis and treatment, and ultimately optimize long-term renal graft survival.

Endoscopic Deflux injection for pediatric transplant reflux: a feasible alternative to open ureteral reimplant

OBJECTIVE

Pediatric renal transplantation is frequently performed using a freely refluxing vesicoureteral anastomosis. The resulting vesicoureteral reflux (VUR) may increase the morbidity of urinary tract infections (UTIs) that commonly occur in this setting, yet open surgical correction of the refluxing anastomosis can prove difficult. We report our experience using endoscopic injection of dextranomer/hyaluronic acid (Deflux) to correct transplant VUR.

MATERIALS AND METHODS

We retrospectively reviewed the charts of patients treated with endoscopic injection of Deflux (Q-Med, Uppsala, Sweden) for VUR into their renal allograft. Indications for inclusion in the study were renal allograft transplantation for primary end-stage renal disease, radiographically proven VUR into the allograft, normal voiding history, and at least one documented febrile UTI. Preoperative and postoperative images, including voiding cystourethrogram and allograft ultrasound, were compared. Location of the transplant orifice and volume of Deflux were recorded. Clinical outcomes, including documented UTI and changes in serum creatinine following treatment, were also assessed.

RESULTS

Eight patients were identified who were treated for transplant VUR, with a total of nine transplant ureters injected. Mean patient age at time of injection was 11.6 years (range: 7-19 years). Post-injection voiding cystourethrograms and allograft ultrasound were available for all patients. Following treatment, four ureters demonstrated resolution of VUR and one ureter demonstrated improvement to grade 1 VUR. The remaining four ureters demonstrated no change in VUR grade. No patients showed any change in their serum creatinine, and no episodes of transplant pyelonephritis have occurred during the follow-up period. Mean post-injection follow-up has been 17.3 months (range 9-26 months).

CONCLUSION

Initial results demonstrate that endoscopic treatment with Deflux is feasible and may provide a less invasive alternative for treatment of transplant VUR. Further investigation with a larger group of patients and longer follow-up is needed.

Urinary tract infection in the renal transplant patient

Urinary tract infection (UTI) is the most common type of bacterial infection contracted by recipients of renal allografts in the post-transplantation period. Fungi and viruses can also cause UTIs, but infections caused by these organisms are less common than those caused by bacteria. Both the lower and upper urinary tract (encompassing grafted or native kidneys) can be affected. Factors that might contribute to the development of UTIs include excessive immunosuppression, and instrumentation of the urinary tract (e.g. urethral catheters and ureteric stents). Antimicrobials are the mainstays of treatment and should be accompanied by minimization of immunosuppression when possible. The use of long-term antimicrobial prophylaxis is controversial, however, as it might increase the likelihood of infective organisms becoming resistant to treatment. There are conflicting data on the associations of post-transplantation UTI with graft and patient survival.

Vesicoureteral reflux after kidney transplantation in children

We analyzed the frequency of vesicoureteral reflux and the factors that favor its appearance after kidney transplantation in pediatric patients. This retrospective analysis examined the prevalence of post-transplant vesicoureteral reflux in a total of 181 kidney transplants performed in children at our center between 1978 and 2004. In patients who required corrective surgery for this problem, we analyzed pretransplant residual diuresis, pretransplant pathology and post-transplant problems related to vesicoureteral reflux. We also analyzed form of presentation, whether reflux was to the graft or to the native kidney, degree of reflux, and surgical technique used to correct reflux. Ten patients (5.5%) needed surgery to correct reflux to the graft (nine children) or to the native kidney (one child). Reflux was manifested as urinary tract infection in six children and progressive graft failure in one. Urethrovesical disorders that favored vesicoureteral reflux were present in eight patients (non-compliance bladder, detrusor overactivity, posterior urethral valves, urethral stenosis). Lengthening the submucosal tunnel stopped urinary tract infections in all 10 patients, whereas six-month voiding cystourethrograms showed resolution in 8 patients and (only) reduction in the degree of reflux in two. The high percentage of post-transplant vesicoureteral reflux in pediatric patients were related with higher frequencies of ureterovesical pathology in children who received the transplant. Lengthening the submucosal ureteral tunnel vesicoureteral reflux was corrected in 80%. We recommend during implantation in children with pretransplant urethrovesical abnormality an initial technique, which utilizes a longer submucosal tunnel such as the Lich-Gregoir.

Urinary Tract Infections and Bladder Dysfunction After Renal Transplantation in Children

PURPOSE

Urinary tract infection remains a major cause of morbidity in pediatric renal transplant recipients. In otherwise healthy children bladder dysfunction increases the susceptibility to urinary tract infection. The aims of this study were to determine whether bladder dysfunction affects the incidence of urinary tract infection after renal transplantation, and to assess the impact of recurrent urinary tract infections on graft function.

MATERIALS AND METHODS

We evaluated bladder function with a questionnaire, uroflowmetry and bladder ultrasound, and renal function with clearance of inulin or iohexol (glomerular filtration rate) in 68 recipients of renal transplants 5 to 20 years old, at 1 to 15 years after transplantation, with and without recurrent urinary tract infections.

RESULTS

Bladder dysfunction was equally common in children with and without recurrent urinary tract infections (68% vs 74%, not significant). Therefore, it had no effect on the incidence of recurrent urinary tract infections. Graft function deteriorated at a faster rate in patients with recurrent urinary tract infections than in those without (mean glomerular filtration rate 45 vs 57 ml per minute per 1.73 m(2) at 4 years after transplantation, p=0.02).

CONCLUSIONS

Bladder dysfunction did not predispose patients to recurrent urinary tract infections. Graft function declined with time in all patients but the rate of deterioration was faster in the group with recurrent urinary tract infections.

Redo Ureteroneocystostomy Using an Extravesical Approach in Pediatric Renal Transplant Patients With Reflux: A Retrospective Analysis and Description of Technique

PURPOSE

Vesicoureteral reflux and pyelonephritis following transplantation may significantly contribute to renal damage and premature graft loss. We report our retrospective experience with redo ureteral reimplantation of refluxing pediatric renal transplants and describe our surgical technique.

MATERIALS AND METHODS

We identified 20 children with a diagnosis of symptomatic post-transplant vesicoureteral reflux, of whom 16 underwent redo ureteral reimplantation. Patient characteristics including etiology of end stage renal disease, presenting symptoms, serum creatinine and postoperative followup were documented. The presence or absence of lower urinary tract dysfunction was documented and values between the 2 groups were analyzed for significance.

RESULTS

All 20 patients presented after assessment for a febrile urinary tract infection, and 35% had concurrent lower urinary tract dysfunction. Median interval between transplantation and vesicoureteral reflux diagnosis was 1.3 years, and mean vesicoureteral reflux grade was 3.2. Patients with lower urinary tract dysfunction presented significantly earlier and had a higher postoperative serum creatinine than those without lower urinary tract dysfunction (1.1 vs 1.7 years, p = 0.048). Redo reimplantation was performed in 94% of patients using an extravesical approach with ureteral stent placement. Seven of 16 patients underwent followup voiding cystourethrogram, with 5 demonstrating resolution and 2, both with lower urinary tract dysfunction, exhibiting persistent vesicoureteral reflux. At a mean followup of 3.6 years 25% of patients experienced recurrent pyelonephritis, while 75% were asymptomatic. One instance of anastomotic stricture occurred in a patient with lower urinary tract dysfunction.

CONCLUSIONS

Effective repair of post-transplantation vesicoureteral reflux can be performed using an extravesical technique, facilitated by preoperative ureteral stent placement. Patients with lower urinary tract dysfunction are likely to present earlier after transplantation than those without lower urinary tract dysfunction, and may have an increased risk of persistent vesicoureteral reflux and renal damage despite surgical correction.

Vesicoureteral reflux after kidney transplantation in children

BACKGROUND

The prevalence and significance of vesicoureteral reflux (VUR) after kidney transplantation in adults varies between authors and there have been few reports in children.

METHODS

We conducted a retrospective study in a single-centre paediatric cohort. Fifty-five of the 84 children who underwent kidney transplantation over a 5-year period were checked with routine cystography after a median of 8 months post-transplantation. Graft function and urinary-tract infections were assessed during the first 6 years after transplantation.

RESULTS

VUR into the graft was present in 58% of the patients. Graft function and incidence of urinary-tract infections were similar in the two groups, independent of VUR. After having excluded infections attributed to the presence of a catheter, actuarial survival rates without pyelonephritis and without pyelonephritis following a first lower urinary-tract infection were worse in patients with VUR (P:=0.017 and P:=0.0039 respectively). None of the eight patients with VUR treated with antibiotic prophylaxis after a first acute pyelonephritis (APN) episode presented subsequent APN after 4.4+/-3.3 years on therapy.

CONCLUSIONS

VUR to the graft occurred in more than half paediatric renal transplant recipients. This condition was associated with an increased risk of APN. Long-term antibiotic prophylaxis seems to be able to prevent APN in transplanted children with VUR.

Vesicopyeloplasty in renal transplant patients: a 20-year followup

Loss of a ureter in a renal transplant patient often results in transplant nephrectomy. In 1973 we used vesicopyelostomy with the bladder directly sutured to the renal pelvis as a method of reconstruction in 2 renal transplant patients following ureteral loss. These patients have been followed for more than 20 years and both renal allografts have functioned well. The status of these patients and a review of the literature on vesicopyelostomy are presented.

Diagnosis and management of urinary tract infection in adults

Images