Kidney transplantation in children with posterior urethral valves

Antenatal and postnatal management of posterior urethral valves: where do we stand?

Introduction

Posterior urethral valve (PUV) is the leading etiology of lower urinary tract obstruction (LUTO) in boys and is an important cause of end-stage renal disease (ESRD) in children. The aim of this article is to review the current status on antenatal intervention for PUV as well as postnatal medical and surgical management.

Main body

MEDLINE, EMBASE, Pubmed and Google Scholar search was conducted throughout December 2020 using the keywords: posterior urethral valves, congenital urinary obstruction, antenatal, valve bladder syndrome, medical, anticholinergics, alpha blocker, antibiotics, biofeedback, diversion, augmentation cystoplasty and renal transplantation. Only papers written in English were included. The relevant literature was summarized. Despite advances in antenatal intervention for fetal LUTO, it remains associated with considerable fetal and maternal morbidity. Patient selection criteria for antenatal intervention are greatly debated. Fetal intervention has resulted in improved perinatal survival in properly selected cases, with a questionable benefit to postnatal renal function. There is decent evidence supporting the use of anticholinergics in infants and young children following valve ablation, with less robust evidence advocating alpha blockers, overnight catheter drainage and biofeedback. The role of urinary diversion remains contentious. Optimizing bladder dynamics is crucial for successful renal transplantation outcomes.

Conclusion

While antenatal intervention has failed to improve renal function outcomes of PUV, patient-centered medical and sometimes surgical interventions can help delay the progression of chronic kidney disease. Lifelong monitoring and management of the associated bladder dysfunction is indispensable even after successful renal transplantation.

Long-Term Outcome of Kidney Transplant Among Iranian Children: A Systematic Review and Meta-Analysis

OBJECTIVES

End-stage kidney disease has dramatic health effects and life consequences in children. Presently, kidney transplant has been globally accepted as a treatment of choice for end-stage kidney disease in both children and adults, leading to better quality of life and longer patient survival. Because of lack of comprehensive information on the outcome of kidney transplant among children in Iran, we aimed to present a proper vision of pediatric kidney transplant in Iran by systematically reviewing the current literature.

MATERIALS AND METHODS

Major databases were searched, including Medline, Web of Knowledge, Google Scholar, Scopus, Cochrane, and the Iranian Scientific Information Database for all eligible studies in accordance with specific keywords. The inclusion criteria for the retrieved studies were determination of graft survival, patient survival, and reasons for graft failure. The exclusion criteria were as follows: (1) a lack of clear results; (2) non-English or non-Persian language format; (3) lack of access to the full-text manuscripts; and (4) case reports, case series, and review papers. A total of 115 studies were initially assessed based on the keywords; of these, 8 met inclusion criteria and were considered for final analysis; these were published between 2005 and 2017.

RESULTS

According to our results, 1-year graft survival rates were overall 89.7%, and 5-year graft survival rates were 65.4%. The 1-year patient survival rates were estimated to be 97.1%, and 5-year patient survival rates were estimated to be 89.8%. Acute rejection, dialysis status before transplant, and inappropriate immunosuppression were the main risk factors.

CONCLUSIONS

Our systematic review and meta-analysis indicated a high success rate of childhood kidney transplant in Iran according to long-term graft and patient survival rates.

Renal transplantation in patients with an augmentation cystoplasty

Background

The effects of renal transplantation in patients with augmentation cystoplasty are still controversial. We retrospectively analyzed nine patients who underwent renal transplantation after augmentation cystoplasty.

Methods

A total of nine patients who underwent augmentation cystoplasty prior to renal transplantation between January 1990 and May 2020 were reviewed. Basic information on augmentation cystoplasty, transplant procedures, and long-term outcomes of renal transplantation were analyzed.

Results

The bowel segments utilized for augmentation cystoplasty were the stomach in two patients (one patient needed revision using the ileum), the ileum in four patients, the ileocolic pouch in one patient, the sigmoid in one patient, and the ureter in one patient. All the cystoplasties were performed prior to renal transplantation. The mean follow-up period after transplantation was 161 months (range, 2–341 months). Two patients had an episode of acute rejection each; however, their graft functions were well-maintained. Five patients had recurrent urinary tract infections, and three of these patients progressed to allograft failure. One patient died from bladder cancer with a functioning graft. Five of nine patients showed well-maintained graft function.

Conclusions

Renal transplantation after bladder augmentation surgery is a major operation requiring a high level of surgical skill. Based on our long-term experiences, we recommend diligent postoperative monitoring for urinary tract infections, optimal catheter use, and use of appropriate antibiotic prophylaxis to avoid severe complications.

Comparative outcome analysis of pediatric kidney transplant in posterior urethral valves children with or without pretransplant Mitrofanoff procedure

BACKGROUND

Urinary diversion using catheterizable channel among posterior urethral valve (PUV) patients may help to alleviate the functional concerns of the bladder on the allograft. Herein, we review our series of PUV patients undergoing renal transplants at a single institution to determine outcomes between those with and without pretransplant Mitrofanoff.

METHODS

PUV cases in our transplant database from 2000 to 2017 were identified. Data collected included clinical demographics, presentation of PUV, bladder function, implementation of dialysis and donor type. Post-transplant variables included graft function, and bladder function including incontinence and UTI development. Comparison between with vs without pretransplant Mitrofanoff patient groups was performed using Fisher's exact and t test analysis.

RESULTS

Overall, 22 cases were analyzed. The majority (77%) had a prenatal diagnosis of PUV, and 23% had a symptomatic presentation. Pretransplant Mitrofanoffs were performed in 40.9% of cases. The overall age at transplant was 10 ± 5 years. Five percent experienced post-transplant incontinence and 23% UTIs. No difference between groups was noted in variables including age at transplant, the timing of PUV diagnosis. Mitrofanoff group patients had more symptomatic febrile UTIs than those without Mitrofanoff (67% vs 15%; P = .03); however, there was no difference in post-transplant UTI development. Furthermore, the Mitrofanoff group seems to have later onset of dialysis or need for transplant (age at the start of dialysis 36 ± 56 vs 156 ± 25 months, P < .001).

CONCLUSION

Our study suggests that patients with early PUV diagnoses who develop symptomatic UTI may benefit from early creation of a Mitrofanoff cathetherizable channel, which is associated with delayed ESRD progression and need for dialysis.

Long-term outcome of kidney transplantation in patients with congenital anomalies of the kidney and urinary tract

BACKGROUND

Congenital anomalies of the kidney and urinary tract (CAKUT) are a leading cause of end-stage kidney failure in the young. However, there is limited information on long-term outcomes after kidney transplantation in this group. We explored the outcomes of kidney transplant in patients with the 3 most common severe forms of CAKUT: posterior urethral valves (PUV), reflux nephropathy and renal hypoplasia/dysplasia.

METHODS

Data were extracted from the Australian & New Zealand Dialysis & Transplant Registry on first kidney transplants performed between 1985 and 2015 in recipients with a primary diagnosis of PUV, renal hypoplasia/dysplasia or reflux nephropathy (under the age of 30 years). Using multivariate Cox regression, we compared death-censored graft survival between the three groups.

RESULTS

One hundred twenty-seven patients with PUV, 245 with hypoplasia/dysplasia and 727 with reflux nephropathy were included. A 10-year graft survival in PUV, hypoplasia/dysplasia and reflux nephropathy was 70%, 76% and 70%, respectively and a 20-year graft survival was 30%, 53% and 49%. After adjusting for age at transplant, graft source and HLA matching, there was evidence for poorer graft survival in PUV (HR, 1.65; 95% CI, 1.15 to 2.38).

CONCLUSIONS

Graft survival of the first transplant in CAKUT is favourable at 10 years; however, recipients with PUV have increased risk of graft loss beyond a 10-year post-transplant, which may be related to bladder dysfunction.

Consensus on the Management of Posterior Urethral Valves from Antenatal Period to Puberty

The need for successful management of posterior urethral valves always captivates the minds of pediatric surgeons. Its success, however, depends on several factors ranging from prenatal preservation of upper tracts to postoperative pharmacological compliance. Regardless of measures available, some cases do not respond and progress to end stage. The management depends on several issues ranging from age and severity at presentation to long-term follow-up and prevention of secondary renal damage and managing valve bladder syndrome. This article is based on a consensus to the set of questionnaires, prepared by research section of Indian Association of Paediatric Surgeons and discussed by experienced pediatric surgeons based in different institutions in the country. Standard operating procedures for conducting a voiding cystourethrogram and cystoscopy were formulated. Age-wise contrast dosage was calculated for ready reference. Current evidence from literature was also reviewed and included to complete the topic.

Favorable Outcomes of Renal Transplant in Children With Abnormal Lower Urinary Tract

OBJECTIVES

Chronic kidney disease caused by lower urinary tract abnormalities is a significant complication in pediatric care. Although there are conflicting reports about clinical outcomes in the past, favorable outcomes have been reported in recent years. Despite this, many centers still refrain from performing renal transplant in these patients. Here, we compared clinical outcomes of renal transplant recipients with and without lower urinary tract abnormalities.

MATERIALS AND METHODS

Our study included 71 renal transplant recipients who were divided into 3 groups: 17 patients with abnormal lower urinary tracts having vesicoureteral reflux (group 1), 7 patients with abnormal lower urinary tracts having bladder dysfunction (group 2), and 47 patients with anatomically and functionally normal lower urinary tracts (group 3). We retrospectively compared demographic features, clinical course, graft survival, pre- and posttransplant incidence of urinary tract infections, and final graft function among the groups.

RESULTS

There were no statistically significant differences among groups regarding median age at time of transplant, graft survival, median creatinine level, and median glomerular filtration rate (P > .05). Significant differences were shown in incidence of urinary tract infections between patients in groups 1 and 2 (abnormal lower urinary tracts) and group 3 (normal lower urinary tracts) before transplant (P < .05). Although frequency of urinary tract infections in groups 1 and 2 were moderately higher than shown in group 3 after transplant, this difference was not statistically significant.

CONCLUSIONS

Although the children with abnormal lower urinary tracts had slightly higher incidence of urinary tract infections, there were no differences between patients with abnormal and normal lower urinary tracts regarding allograft survival and function. In addition, proper follow-up of patients before and after transplant, based on our experience, should include educating patients and their parents about potential complications after transplant for the best outcome of renal transplant.

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.

Does bladder augmentation negatively affect renal transplant outcome in posterior urethral valve patients?

OBJECTIVE

Although renal transplant (RT) is a safe and effective treatment for end-stage renal disease, the outcome of RT has been mixed for posterior urethral valve (PUV) patients. In addition, some PUV patients need an augmentation cystoplasty (AC), which may negatively affect their RT outcome. The aim of this study is to compare RT outcome between PUV children with and without AC.

MATERIALS AND METHODS

Between 1985 and 2012 a total of 309 children received 369 RTs at our institution. Among these patients, 36 were had classified as having PUV. Of these, 12 underwent an AC before RT (AC group) and 24 did not (controls). Data, including age at transplant, allograft source, urological complications, urinary tract infection (UTI) incidence, the presence of vesicoureteral reflux (VUR), and patient and graft survival, were compared between groups.

RESULTS

Mean age at RT and mean follow-up were 7.6 versus 7.9 years and 8.9 versus 7.9 years in the AC group and in the control group, respectively (not significant [NS]). Allografts were from living donors in 50% of the AC group and in 41.6% of the controls (NS). The rate of UTI was 0.02 UTI/patient/year and 0.004 UTI/patient/year in the AC and control group, respectively (p = 0.001). Of the nine patients with UTI in the augmented group, five (55.5%) had VUR, while 5/8 (62.5%) patients in the control group with UTI had VUR. All patients with VUR in either group had UTIs previously. Of the five AC patients with more than three UTIs, two (40%) were non-compliant with clean intermittent catheterization (CIC), and UTI incidence was not associated with either a Mitrofanoff conduit or the urethra being used for CIC. Graft function at the end of study was 87.8 ± 40.5 ml/min/m(2) in the AC group and 88.17 ± 28.20 ml/min/m(2) in the control group (NS). The 10-year graft survival rate was 100% in AC group and 84.8% in controls. Two patients in the AC group lost their grafts (mean follow-up 13.3 ± 0.8 years) and five in the control group (mean follow-up 7.1 ± 4.7 years).

CONCLUSIONS

Bladder augmentation does not negatively affect renal outcome in PUV patients undergoing transplantation. However, recurrent UTIs are more frequent in transplanted PUV patients with an AC than in those without AC, and they are generally related to non-compliance with CIC or the presence of VUR but, mostly, they will not result in impaired graft function.

Long-term consequences of posterior urethral valves

Posterior urethral valves (PUV) are the most common congenital cause of bladder outlet obstruction in infancy, and it is the effect of this obstruction on the bladder and the kidneys that will decide a patient's prognosis. With the improvements in diagnosis and treatments, what was previously a poor prognosis for boys with PUV has improved, and more patients will encounter the long-term sequelae of PUV during puberty and adulthood. In these patients the long-term prognosis in terms of renal and bladder function and fertility, as well as the risk of malignancy in those whose bladders were augmented with gastrointestinal segments, is still a matter of great concern and all of these topics will be discussed in this article.

Renal transplant outcome in children with an augmented bladder

OBJECTIVE

Studies evaluating renal transplant (RT) outcome in children who underwent an augmentation cystoplasty (AC) are contradictory and the current knowledge is based on studies with a limited number of patients. The aim of this study is to compare RT outcome between children who underwent AC and those without augmentation.

PATIENTS AND METHODS

A total of 20p who underwent an AC prior to the RT (12 with ureter and 8 with intestine) were enrolled in the study and were compared to a control group of 24p without AC, transplanted in the same time period (1991-2011). Data including; age at transplant, allograft source, urological complications, urinary tract infections (UTI) incidence, the presence of VUR, and patient and graft survival were compared between the groups.

RESULTS

Mean age at RT and mean follow-up were 9.7 vs. 7.9 years and 6.9 vs. 7.9 years in the AC group and control group, respectively (NS). The graft originated in living donors for 60% of AC patients and 41.6% of the control RT patients. The rate of UTI were 0.01 UTI/patient/year and 0.004 UTI/patient/year in the augmented group and controls, respectively (p = 0.0001). In the AC group of 14p with UTIs, 10 (71%) had VUR and 5p out of 8 (62.5%) in the control group had VUR. In the AC group, of the 7p with ≥3 UTIs, 3 (43%) were non-compliant with CIC and the incidence of UTIs was not related with the type of AC or if the patient did CIC through a Mitrofanoff conduit or through the urethra. Graft function at the end of study was 92.9 ± 36.85 ml/min/m(2) in the AC group and 88.17 ± 28.2 ml/min/m(2) in the control group (NS). Graft survival at 10 years was also similar 88% in the AC group and 84.8% in controls. In the AC group 3p lost their grafts and 5 in the control group with respective mean follow-up of 10.6 ± 4.3 and 7.1 + 4.7 years.

CONCLUSION

There are no significant differences in the RT outcome between children transplanted with AC or without. However, recurrent UTIs are more frequent in the former group and these UTIs are related with non-compliance with CIC or the presence of VUR but, even so, UTIs will not lead to impaired graft function in most of the patients.

Should a complex uropathy be a contraindication for renal transplantation in children?

BACKGROUND

Anatomic and functional disorders of the lower urinary tract represent up to 40% of the causes of renal failure in children. Several centers avoid renal transplantation in these patients because of the high risk of complications and lower graft survival. The aim of this work was to determine the frequency of urinary tract abnormalities (UTAs) among our pediatric series, and to compare the frequency of complications, function, and long-term graft survival among patients without versus with UTA.

METHODS

This single-center, retrospective study compared outcomes between pediatric recipients with versus without UTA. We analyzed demographic features, etiology, pretransplant protocol, urinary tract rehabilitation, incidence of complications, rejection events, as well as graft function and survival.

RESULTS

Among 328 pediatric cases performed between 1998 and 2008, we excluded nine patients due to incomplete medical records, analyzing 319 procedures in 312 patients. Sixty-seven patients (21%) had UTA. The average age, weight, and height at the time of grafting were significantly lower in the urologic group: 11.1 versus 12.6 years, 28.8 versus 34.4 kg; 125.4 versus 138.4 cm, respectively. There were significantly higher frequencies of a transperitoneal approach and vena cavae and aortic anastomoses among patients with UTA (P < .001), posing a greater technical challenge in this population. No differences in creatinine levels were observed at 0.5, 1, 2, 5, and 10 years: 1.3 versus 1.6 at 5 years, and 1.4 versus 1.5 at 8 years. Urologic complications, including urinary tract infections (UTIs), occurred among 80.6% of patients with UTA versus 42.1% in the non-UTA group (P < .001). UTIs appeared predominantly in patients with UTA (62.7% vs 35.3%, P < .001), representing a 2.7-fold risk compared with those children transplanted for other reasons. Rejection incidence was similar in both groups (49.8%). There was no significant difference in 5-y (89.8% vs 85%) or 10-year (83% vs 67%) graft survivals between the groups (P = .162).

CONCLUSION

Our results demonstrated that with proper interdisciplinary care, graft and patient survivals of pediatric recipients with UTAs were not affected; therefore, these patients should not be rejected for transplantation.

CONGENITAL URINARY BLADDER OUTLET OBSTRUCTION

The term congenital ‘bladder outlet obstruction (BOO)’ describes the collection of conditions in which the normal, urethral egress of urine from the fetal bladder is impaired. The term is interchangeable with fetal ‘lower urinary tract obstruction’, as used by other authors. After considering normal urinary tract embryology, we describe the epidemiology of congenital BOO and the primary anatomical disorders associated with it. We then proceed to describe its fetal and postnatal clinical manifestations and then consider therapies and interventions which have been used to manage the condition. We not only focus on urethral and bladder disease with constitutes BOO itself, but also describe associated kidney disorders which, via chronic renal excretory failure, are important causes of morbidity. Rather than provide an exhaustive review, we emphasise studies published in the last decade, and therefore readers are referred to other reviews citing numerous earlier references.