Assessing the value of ureteral stent placement in pediatric kidney transplant recipients. Transplantation. 2008;85:986-991. [PMID: 18408579 DOI: 10.1097/tp.0b013e318169bf11]

Paediatric kidney transplantation: Towards a framework for pretransplant urological evaluation

The role of the urologist in paediatric kidney transplantation has evolved alongside advances in management for the various causes of end-stage kidney disease. Improvements in antenatal intervention and postnatal care have seen children with increasingly complex urological anomalies survive until transplant. Once solely responsible for the oversight of a child's surgical care, the paediatric urologist now works within a multidisciplinary transplant team, alongside transplant surgeons, paediatric nephrologists, transplant coordinators, psychologists, social workers, and transitional care specialists. We sought to identify available pretransplant evaluation frameworks to guide urological preparation and decision-making. Drawing from available evidence and reflecting on multi-institutional experience, we propose a streamlined approach to urologic assessment, which recognises that optimal transplant outcomes in this heterogenous cohort require lower urinary tract dysfunction to be carefully defined preoperatively.

Pearls and Pitfalls in Pediatric Kidney Transplantation After 5 Decades

Worldwide, over 1,300 pediatric kidney transplantations are performed every year. Since the first transplantation in 1959, healthcare has evolved dramatically. Pre-emptive transplantations with grafts from living donors have become more common. Despite a subsequent improvement in graft survival, there are still challenges to face. This study attempts to summarize how our understanding of pediatric kidney transplantation has developed and improved since its beginnings, whilst also highlighting those areas where future research should concentrate in order to help resolve as yet unanswered questions. Existing literature was compared to our own data of 411 single-center pediatric kidney transplantations between 1968 and 2020, in order to find discrepancies and allow identification of future challenges. Important issues for future care are innovations in immunosuppressive medication, improving medication adherence, careful donor selection with regard to characteristics of both donor and recipient, improvement of surgical techniques and increased attention for lower urinary tract dysfunction and voiding behavior in all patients.

Review of stentless, tubeless, apposed renal (STAR) transplant wound management programme

INTRODUCTION We aimed to review the necessity of conventional interventions in renal transplant for preventing complications arising out of the use of wound drains, ureteral stents and stapled skin closures. METHODS We reviewed a series of 33 patients who received stentless, tubeless/drainless and suture-apposed living donor renal transplants (STAR group) and compared the results to a control non-STAR group of 36 patients in whom all three interventions of drains, stents and skin staples were used. RESULTS No significant differences in demographics and clinical characteristics were observed between the two groups. With regard to the overall surgical complications, no significant differences in terms of wound infection, seroma, perinephric collections, urinoma, bacteriuria or vascular complications were observed between the groups. When analysed according to the interventions specific for preventing complications, although slightly more asymptomatic perinephric collections were observed and two lymphoceles required treatment in the STAR group, these differences were not statistically significant. Similarly, no significant differences in ureteric or skin-related complications were observed between the groups. Both groups had comparable good outcomes for renal function, graft survival and patient survival. CONCLUSION The routine use of ureteric stents, drains or skin staples may not be necessary for uncomplicated renal transplants. Potential complications associated with the placement of these interventions can be avoided without compromising on the safety of patients and/or the outcome of transplants.

Surgical complications in pediatric kidney transplantation-Incidence, risk factors, and effects on graft survival: A retrospective single-center study

The field of pediatric kidney transplantation remains challenging due to an ongoing lack of size-matched grafts and anatomical peculiarities. In the current study, we investigated the incidence of surgical complications in pediatric recipients, with a focus on risk factors and effects on graft outcome. We retrospectively reviewed all 2386 kidney transplantations at our institution from January 2005 until December 2018. Of these, 221 transplants were performed in pediatric recipients, defined as under the age of 18 years. Donor-recipient body surface area ratios were calculated to evaluate the effects of size mismatching. Regression analyses were performed to identify independent risk factors for surgical complications and graft survival, respectively. Perioperative surgical complications requiring revision were observed in 34 (15.4%) cases. Leading cause for revision were vascular complications such as thrombosis or stenosis (n = 15 [6.8%]), which were significantly more frequent in case of young donors, (ie, donor age <6 years; OR: 4.281; CI-95%:1.385-13.226; P = .012), previous nephrectomy (OR: 3.407; CI-95%:1.019-11.387; P = .046), and en-bloc grafts (OR: 4.923; CI-95%:1.355-17.884; P = .015), followed by postoperative hemorrhage (n = 10 [4.5%]), ureteral complications (n = 8 [3.6%]), and lymphoceles (n = 7 [3.2%]). Median follow-up was 84.13 (0.92-175.72) months. One-, 5-, and 10-year graft survival rates were 97.1%, 88.9%, and 65.1%, respectively. Except for vascular complications (HR: 4.727; CI-95%:1.363-16.394; P = .014), none of the analyzed surgical morbidities significantly influenced graft survival. In conclusion, pediatric kidney transplantation achieves excellent long-term results. However, meticulous surgical technique and continuous postoperative monitoring are imperative for early detection and treatment of imminent vascular complications, especially in case of young donors and en-bloc grafts.

Epidemiology of and Risk Factors for BK Polyomavirus Replication and Nephropathy in Pediatric Renal Transplant Recipients: An International CERTAIN Registry Study

BACKGROUND

BK polyomavirus-associated nephropathy (BKPyVAN) constitutes a serious cause of kidney allograft failure, but large-scale data in pediatric renal transplant recipients and a comprehensive analysis of specific risk factors are lacking.

METHODS

We analyzed the data of 313 patients in the Cooperative European Pediatric Renal Transplant Initiative Registry, with an observation period of 3.3 years (range, 1-5). The net state of immunosuppressive therapy was assessed by the modified Vasudev score.

RESULTS

Presumptive BKPyVAN (defined as sustained [>3 wk] high-level BK viremia >10 copies/mL) within 5 years posttransplant occurred in 49 (15.8%) of 311 patients, and biopsy-proven BKPyVAN in 14 (4.5%) of 313. BKPyV viremia was observed in 115 (36.7%) of 311 patients, of whom 11 (9.6%) of 115 developed viremia late, that is, after the second year posttransplant. In 6 (12.5%) of 48 patients with high-level viremia and in 3 (21.4%) of 14 with BKPyVAN, this respective event occurred late. According to multivariable analysis, BKPyV viremia and/or BKPyVAN were associated not only with a higher net state of immunosuppression (odds ratio [OR], 1.3; P < 0.01) and with tacrolimus-based versus ciclosporin-based immunosuppression (OR, 3.6; P < 0.01) but also with younger recipient age (OR, 1.1 per y younger; P < 0.001) and obstructive uropathy (OR, 12.4; P < 0.01) as primary renal disease.

CONCLUSIONS

Uncontrolled BKPyV replication affects a significant proportion of pediatric renal transplant recipients and is associated with unique features of epidemiology and risk factors, such as young recipient age, obstructive uropathy, and overall intensity of immunosuppressive therapy. BKPyV surveillance should be considered beyond 2 years posttransplant in pediatric patients at higher risk.

How to stent the ureter after kidney transplantation in children?-A comparison of two methods of urinary drainage

Ureteral stenting after pediatric renal transplantation serves to prevent obstruction and urinary leakage, but can also cause complications. This study compares the complication rates of both methods. Data were retrospectively collected at Erasmus MC, Rotterdam, the Netherlands (splint group, n = 61) and Hospital for Sick Children, Toronto, Canada (JJ catheter group, n = 50). Outcome measures included urological interventions and incidence of UTIs during the first 3 months post-transplantation. The splint was removed after a median of 9 (IQR 8-12), the JJ catheter after 42 (IQR 36-50) days. Seven (11.5%) children in the splint group needed at least one urological re-intervention versus two in the JJ catheter group (P-value .20). UTIs developed in 19 children (31.1%) in the splint group and in twenty-five (50.0%) children in the JJ catheter group (P-value .04), with a total number of 27 vs. 57 UTIs (P-value .02). Nine (33.3%) vs. 35 (61.4%) of these, respectively, occurred during the presence of the splint (P-value <.001). Children with a JJ catheter developed more UTIs than children with a splint; the latter, however, tended to require more re-interventions. Modification of either method is needed to find the best way to stent the ureter.

Infection-related hospitalizations after kidney transplantation in children: incidence, risk factors, and cost

BACKGROUND

Infection is the leading cause of death and hospitalization in renal transplant recipients. We describe posttransplant infections requiring hospitalization, their risk factors and cost in a national pediatric kidney transplantation cohort.

METHODS

Data on renal transplant recipients <20 years were extracted from the French National Medicoadministrative Hospital Discharge database between 2008 and 2013 and matched with the Renal Transplant Database. We used Cox regression to study risk factors of hospitalization and calculated the instantaneous risk of hospitalization per month for all infections and by infection type.

RESULTS

Five hundred and ninety-three patients were included, and 660 infection-related hospitalizations were identified in 260 patients. The leading cause of hospitalization was urinary tract infection (UTI), followed by viral infection (16.6 and 15.6 per 100 person-years, respectively). Risk factors were younger age at transplantation, high number of HLA mismatches, and use cyclosporine rather than tacrolimus as first anticalcineurin treatment. Risk factors varied by infection type. Female gender, uropathy, cold ischemia time, and cyclosporine were associated with increased risk of UTI, while only age at transplantation inversely correlated with virus-related hospitalizations. Instantaneous risk of all infections decreased with time, except for cytomegalovirus (CMV) infection that displayed a peak at 6 months posttransplantation after prophylaxis withdrawal. Total cost of infection-related hospitalizations was 1600 kilo-euro (k€) (933 €/person-years).

CONCLUSIONS

This study highlights the high burden of infection in transplanted pediatric patients, especially the youngest. This should be considered both for pretransplantation information and designing procedures aiming to decrease hospitalization rate and duration.

Pediatric kidney transplantation

Since first performed in 1954, kidney transplantation has evolved as the preferred long-term treatment of children with end stage renal disease (ESRD). The etiology of chronic kidney disease (CKD) and ESRD in children is broad and can be quite complicated, necessitating a multidisciplinary team to adequately care for these patients and their myriad needs. Precise surgical techniques and modern protocols for immunosuppression provide excellent long-term patient and graft survival. This article reviews the many etiologies of renal failure in the pediatric population focusing on those most commonly leading to the need for kidney transplantation. The processes of evaluation, kidney transplantation, short-term and long-term complications, as well as long-term outcomes are also reviewed.

Urologic Complications After Renal Transplant: A Single-Center Experience

OBJECTIVES

Urologic complications after kidney transplant are associated with significant morbidity, mortality, and prolonged hospital stay. An intervention or second surgical procedure is frequently required. Here, we report urologic complications in adult kidney recipients.

MATERIALS AND METHODS

Since 2006, 171 adult kidney transplant procedures have been performed at the Gazi University Transplantation Center (Ankara, Turkey). Among these patients, there were 65 adult female (38%) and 106 adult male (62%) recipients. Donor source included 61 deceased donations (36%) and 110 living related donations (64%). The Haberal corner-saving technique was used for ureteroneocystostomy anastomosis. All recipients received a calcineurin-based triple immunosuppression regimen. All recipients also received trimethoprim/sulfamethoxazole prophylaxis for 3 months after transplant.

RESULTS

In the 171 adult kidney recipients analyzed for urologic complications, mean age was 32.5 ± 14.1 years (median: 32.5 y; range, 18-67 y); mean donor age was 41 ± 14.2 years (median: 42 y). We focused on 3 specific urologic complications: urine leak, ureteric stenosis, and symptomatic vesicoureteral reflux. In our study group, urologic complications were encountered in 7 patients (4%), with 5 complications detected in the early period and 2 complications detected in the late period. No symptomatic vesicoureteral reflux complications were shown in this study group. Urologic complications did not result in any patient deaths or graft loss.

CONCLUSIONS

In this study, the Haberal corner-saving suture technique with double J stent seemed to have a protective effect for development of urologic complications.

Outcome of the Double-J Stent Placement in Pediatric Kidney Transplant: A Single Center Experience

OBJECTIVES

Double J stent placement at kidney transplant may reduce stenosis or leakage complication rates. However, placement may also increase risk for early urinary tract infection (ie, < 3 mo after transplant). In children, the usefulness of double J stent placement is not well defined.

MATERIALS AND METHODS

We analyzed retrospective data from children who received transplants at the Gazi University Transplantation Center and Pediatric Nephrology (Ankara, Turkey) for outcomes related to double J stents. At our center, double J stent placement decision is made by the transplant surgery team during operation. Placements were routinely performed in all transplant recipients. Stent removal occurs within 6 week after transplant.

RESULTS

Among 42 transplants since 2006, early urinary tract infection was seen in 7% and stenosis in 3.6% of patients, with no leakage reported. Mean stent removal time was 6 ± 0.5 weeks. Early urinary tract infection was seen in 3 recipients with posterior urethral valve and neurogenic bladder (2 recipients) and meningoma cells and neurogenic bladder (1 recipient). All 3 recipients with early urinary tract infection received clean intermittent catheterization after transplant for adequate emptying of the bladder. In our study group, stent complications such as migration (2 patients) and hematuria (1 patient) were seen, but crusting, breakage, and stone formation were not seen. The 3 patients with urinary tract infection had neurogenic bladder types, complicating the urine outflow system. Stent placement was not a significant risk factor for early urinary tract infection and but had a protective effect.

CONCLUSIONS

In our study group, we observed no risk factors for routine double J stent placement in pediatric renal transplant procedures. Stent placement was not a risk factor for early urinary tract infection. However, regardless of stent placement, when a recipient had complicated urologic outflow problems, infection became a long-term hurdle.

Ureteral stent placement and immediate graft function are associated with increased risk of BK viremia in the first year after kidney transplantation

Ureteral stent (UrSt) placement has been shown to be a significant independent risk factor for BK viruria, viremia, and BK virus nephropathy. We assessed whether this observation could be validated at our high volume kidney transplant center that has had a strong historical focus on BK virus nephropathy detection. We performed a retrospective case-control study of adults receiving a kidney-only transplant and followed for 1 year between 2004 and 2011 with uniform immunosuppression and use of blood BK virus PCR screening protocol. Among 1147 patients, 443 (38.6%) received a UrSt and 17.2% with a UrSt had BK viremia versus 13.5% without stent (odds ratio 1.33; 95% CI: 1.00-1.78). We confirmed a previously reported association between immediate graft function (IGF) and higher rate of BK viremia (15.7% vs. 5.9% in patients without IGF). On multivariable competing risks Cox regression in patients with IGF, UrSt (adjusted hazard ratio [aHR] 1.35; 95% CI: 1.04-1.75) and African American race (aHR 1.47; 95% CI: 1.04-2.09) significantly increased the risk for BK viremia. In the largest sample size to date, we confirmed that UrSt placement during kidney transplant surgery is a risk factor for BK viremia within the first year post-transplant and that IGF is associated with BK viremia.

Clinical and economic consequences of first-year urinary tract infections, sepsis, and pneumonia in contemporary kidney transplantation practice

We examined United States Renal Data System registry records for Medicare-insured kidney transplant recipients in 2000-2011 to study the clinical and cost impacts of urinary tract infections (UTI), pneumonia, and sepsis in the first year post-transplant among a contemporary, national cohort. Infections were identified by billing diagnostic codes. Among 60 702 recipients, 45% experienced at least one study infection in the first year post-transplant, including UTI in 32%, pneumonia in 13%, and sepsis in 12%. Older recipient age, female sex, diabetic kidney failure, nonstandard criteria organs, sirolimus-based immunosuppression, and steroids at discharge were associated with increased risk of first-year infections. By time-varying, multivariate Cox regression, all study infections predicted increased first-year mortality, ranging from 41% (aHR 1.41, 95% CI 1.25-1.56) for UTI alone, 6- to 12-fold risk for pneumonia or sepsis alone, to 34-fold risk (aHR 34.38, 95% CI 30.35-38.95) for those with all three infections. Infections also significantly increased first-year costs, from $17 691 (standard error (SE) $591) marginal cost increase for UTI alone, to approximately $40 000-$50 000 (SE $1054-1238) for pneumonia or sepsis alone, to $134 773 (SE $1876) for those with UTI, pneumonia, and sepsis. Clinical and economic impacts persisted in years 2-3 post-transplant. Early infections reflect important targets for management protocols to improve post-transplant outcomes and reduce costs of care.

Ureteral Stent Placement Increases the Risk for Developing BK Viremia after Kidney Transplantation

The placement of ureteral stent (UrSt) at kidney transplantation reduces major urological complications but increases the risk for developing nephropathy from the BK virus. It is unclear whether UrSt placement increases nephropathy risk by increasing risk of precursor viral replication or by other mechanisms. We retrospectively investigated whether UrSt placement increased the risk for developing BK Viremia (BKVM) in adult and pediatric kidney transplants performed at the University of Florida between July 1, 2007, and December 31, 2010. In this period all recipients underwent prospective BKV PCR monitoring and were maintained on similar immunosuppression. Stent placement or not was based on surgeon preference. In 621 transplants, UrSt were placed in 295 (47.5%). BKVM was seen in 22% versus 16% without UrSt (P = 0.05). In multivariate analyses, adjusting for multiple transplant covariates, only UrSt placement remained significantly associated with BKVM (P = 0.04). UrSt placement significantly increased the risk for BKVM. Routine UrSt placement needs to be revaluated, since benefits may be negated by the need for more BK PCR testing and potential for graft survival-affecting nephritis.

Effect of ureteric stents on urological infection and graft function following renal transplantation

AIM: To compare urological infections in patients with or without stents following transplantation and to determine the effect of such infections on graft function.

METHODS: All 285 recipients of kidney transplantation at our centre between 2006 and 2010 were included in the study. Detailed information including stent use and transplant function was collected prospectively and analysed retrospectively. The diagnosis of urinary tract infection was made on the basis of compatible symptoms supported by urinalysis and/or microbiological culture. Graft function, estimated glomerular filtration rate and creatinine at 6 mo and 12 mo, immediate graft function and infection rates were compared between those with a stent or without a stent.

RESULTS: Overall, 196 (183 during initial procedure, 13 at reoperation) patients were stented following transplantation. The overall urine leak rate was 4.3% (12/277) with no difference between those with or without stents - 7/183 vs 5/102, P = 0.746. Overall, 54% (99/183) of stented patients developed a urological infection compared to 38.1% (32/84) of those without stents (P = 0.0151). All 18 major urological infections occurred in those with stents. The use of stent (Wald χ² = 5.505, P = 0.019) and diabetes mellitus (Wald χ² = 5.197, P = 0.023) were found to have significant influence on urological infection rates on multivariate analysis. There were no deaths or graft losses due to infection. Stenting was associated with poorer transplant function at 12 mo.

CONCLUSION: Stents increase the risks of urological infections and have a detrimental effect on early to medium term renal transplant function.

Obstructive uropathy is associated with polyomavirus viremia in pediatric kidney transplantation

BKVN leads to allograft dysfunction following kidney transplantation and is preceded by BK viremia. Studies in pediatric kidney transplant recipients reveal an incidence of viruria ranging from 18% to 33%, viremia 6-16%, and BKVN 2-8%. Specific risk factors have not been clearly elucidated. Retrospective chart review of pediatric kidney transplants performed from January 2005 through December 2009; to identify risk factors associated with BK viremia in pediatric kidney transplant recipients from a single center. Of the 93 patients who received kidney transplants in the study period, 22 (24%) developed BK viruria, including 12 (13%) who developed viremia. One patient with viremia (1.6%) had BKVN. Obstructive uropathy was identified as the cause of ESKD in 22 (24%) of all recipients. 27% (n = 6) of these 22 patients developed viremia, while only 8.5% (6/71) with ESKD from another cause had viremia (p = 0.001). No other examined variable differed between the two groups. Although the overall incidence was no higher than other reported series, we identified that BK disease was more frequent in children with OU. A higher index of suspicion for invasive BK disease is necessary in patients with OU who receive kidney allografts. Transplant protocols may need to consider underlying cause of ESKD when designing screening protocols for BK disease in children after kidney transplantation.

The BK virus in renal transplant recipients-review of pathogenesis, diagnosis, and treatment

The BK virus, a DNA virus from the Polyomavirus group, represents an opportunistic infection of immunosuppressed transplant recipients. Though the virus was discovered approximately 40 years ago, the emergence of BK virus nephropathy since 1995 onwards, with associated high graft loss rates, has revolutionized renal transplantation medicine. Kidney transplant professionals realized that the consequences of over-immunosuppression were as severe as the consequences of under-immunosuppression and we entered the era of immunosuppressive minimization. Despite this recognition, the optimal testing type for BK virus infections and frequency of testing are hotly debated. Similarly, optimal treatment strategies remain sources of intense controversy. The authors review the current strategies of screening, diagnosis, and possible treatment, and also review the amount and quality of evidence in favor or against. Similarities and differences between cytomegalovirus, Epstein-Barr virus, and BV virus, the three major viral infections in kidney transplantation, are highlighted.

There is no need to stent the ureterovesical anastomosis in live renal transplants

Double-J (DJ) stents are used in urology practice for various reasons. In renal transplantation, DJ stenting is used to treat the complications like urine leak and ureteric obstruction. However, the role of routine or prophylactic DJ stenting during renal transplantation is debatable. Most of the urinary complications occurring following renal transplantation are because of poor surgical technique and transplant ureteric ischemia. Routine DJ stenting cannot be a substitute for sound surgical technique, which avoids ureteric devascularization and create watertight ureterovesical anastomosis. DJ stenting increases the risk for complications like recurrent urinary tract infection, stent encrustation, stone formation, hematuria, and severe storage lower urinary tract symptoms. Routine DJ stenting during renal transplantation is not mandatory. It can harm an immunosuppressed renal transplant recipient by predisposing to various complications.

Cost-efficient screening for BK virus in pediatric kidney transplantation: a single-center experience and review of the literature

BKVNP is an increasingly recognized cause of graft dysfunction and loss in kidney transplant recipients. Protocols for BKV screening and for the diagnosis of BKVNP are still evolving. PCR-based BKV detection became available at our institution in 2007, when we began using it according to published guidelines. We subsequently reviewed our experience with urine and plasma BKV PCR testing in our pediatric kidney transplant recipient population. We found rates of viruria, viremia, and BKVNP that were similar to the published literature. We also conducted a cost analysis suggesting that urine PCR testing, as used by us, is not cost efficient in the detection of BKV. We conclude that plasma only-based PCR testing for BKV may be sufficient in most clinical settings.