Ureteral complications: analysis of risk factors in 1000 renal transplants

Kidney transplantation from expanded criteria donors: an increased risk of urinary complications - the UriNary Complications Of Renal Transplant (UNyCORT) study

OBJECTIVES

To assess the impact of expanded criteria donors (ECD) on urinary complications in kidney transplantation.

PATIENTS AND METHODS

The UriNary Complications Of Renal Transplant (UNyCORT) is a cohort study based on the French prospective Données Informatisées et VAlidées en Transplantation/Computerized and VAlidated Data in Transplantation (DIVAT) cohort. Data were extracted between 1 January 2002 and 1 January 2018 with 1-year minimum follow-up, in relation to 44 pre- and postoperative variables. ECD status was included according to United Network for Organ Sharing (UNOS) definition. The primary outcome of the UNyCORT study was the association between the donor's ECD/standard criteria donors (SCD) status and urinary complications at 1 year in uni- and multivariate analysis. Sub-group analysis, stratified analysis on ECD/SCD donor's status and transplant failure analysis were then conducted.

RESULTS

Between 1 January 2002 and 1 January 2018, 10 279 kidney transplants in adult recipients were recorded within the DIVAT network. A total of 8559 (83.4%) donors were deceased donors and 1699 (16.6%) were living donors (LD). Among donation after circulatory death (DCD) donors, 224 (2.85%) were uncontrolled DCD and 93 (1.09%) were controlled DCD donors. A total of 3617 (43.9%) deceased donors were ECD. The overall urological complication rate was 16.26%. The donor's ECD status was significantly associated with an increased risk of urological complications at 1 year in multivariate analysis (odds ratio: 1.50, 95% CI 1.31-1.71; P < 0.001) and especially with stenosis and ureteric fistulae at 1 year. There is no association with LD, uncontrolled and controlled DCD. The placement of an endo-ureteric stent was beneficial in preventing urinary complications in all donors and particularly in ECD donors.

CONCLUSION

The donor's ECD status is associated with a higher likelihood of stenosis and ureteric fistulae at 1 year. Recipients of grafts from ECD donors should probably be considered for closer urological monitoring and systematic preventive measures.

Urological Complications in Kidney Transplant Recipients: Analysis of the Risk Factors and Impact on Transplant Outcomes in the Era of “Extended Criteria Donors”

Urological complications (UC) following kidney transplantation (KT) are associated with increased morbidity. The aim of this study is to evaluate the risk factors for UC in the era of “extended criteria donors” (ECD) and their impact on patient and graft survivals. A retrospective monocentric study of all patients undergoing KT from 2010 to 2019 with a follow-up ≥30 days was performed. Out of 459 patients (males: 296 (64.5%); age: 57 (19–77) years) enrolled, 228 (49.7%) received ECD organs, moreover, 166 (67.2%) grafts had a cold ischemia time ≥10 h. UCs were reported in 32 (7%) patients. In 21 (65.6%) cases UC occurred within 3 months post-KT and 24 (5.2%) were associated with early urinary tract infection (UTI). The overall 5 year patient and graft survival rates were 96.5% and 90.6%, respectively. UC decreased graft survival (UC-group: 75.0% vs. noUC-group: 91.8%, p < 0.001), especially if associated with early UTI (UC-group: 71.4% vs. noUC-group: 77.8%, p < 0.001). At multivariate analysis, early UTI after KT (OR: 9.975, 95%-IC: 2.934–33.909, p < 0.001) and delayed graft function (DGF) (OR: 3.844, 95%-IC: 1.328–11.131, p: 0.013) were significant risk factors for UC, while ECD graft did not increase the risk of post-transplant UC. ECD grafts are not associated with UC. DGF and early UTI post-KT increase the risks of UC and reduce graft survival in the long-term. Therefore, aggressive management of early post-transplant UTI and strategies to reduce DGF incidence, such as machine preservation, are essential to prevent UC after KT.

Ultra-high-risk pregnancies in women after renal transplantation

OBJECTIVES

This study evaluates pregnancy outcomes in renal transplant recipients who have additional obstetrical, surgical, or urological risk factors.

STUDY DESIGN

Data from our transplantation and obstetrical databases were retrospectively analyzed to identify all women of reproductive age who had undergone renal transplantation between 1999 and 2013 at our tertiary referral center and had subsequently become pregnant. Characteristics of pregnancy and perinatal outcome parameters; obstetrical, urological, and surgical risk factors; and graft function were assessed. Descriptive data analysis, Fisher's exact test, unpaired Student's t-test and one-way analysis of the variance were performed.

RESULTS

The overall pregnancy rate after renal transplantation was 5% (n=13). 77% of the patients (n=10) had ultra-high-risk pregnancies due to additional risk factors. These included twin pregnancy, placenta previa/percreta, hypertension; previous heart transplantation, previous myocardial infarction; postoperative lymphocele, urinary leakage, hydronephrosis, or vesico-ureteral reflux. Two patients had two consecutive pregnancies. A total of 12 deliveries with 13 newborns were achieved. Cesarean section and preterm delivery rates were 67% and 50%, respectively. Mean gestational week at delivery was 36 ± 3. Mean creatinine levels were higher in women with preterm deliveries and in those of advanced age. Mean time between transplantation and delivery was 79 ± 36 months. All patients had adequate graft function after a mean follow-up of 128 ± 50 months after renal transplantation.

CONCLUSIONS

Pregnant women after renal transplantation commonly present with additional risk factors. In these ultra-high-risk pregnancies successful outcomes can be achieved in a multidisciplinary setting. Adequate graft function and urinary tract evaluation is necessary.

Value of routine voiding cystourethrography after renal transplantation

The impact of vesicoureteral reflux (VUR) on renal allograft outcomes is debatable, with small cohort studies reporting controversial results. The objective of this retrospective study was to evaluate long-term clinical effects of early VUR in a large cohort of kidney transplant patients. Posttransplantation voiding cystourethrography was used to evaluate 646 consecutive kidney transplant recipients before discharge. The study endpoints included VUR grade, death-censored graft or patient survival, renal function, proteinuria and occurrence of urinary tract infections (UTIs). Of the 646 recipients, 263 (40.7%) were diagnosed with VUR. VUR grade II was most common (19.8%), followed by grades III (10.2%), I (7.9%) and IV (2.8%). VUR was less common in transplantations performed by experienced compared to inexperienced surgeons (36% vs. 48%; p = 0.004). VUR did not affect death-censored graft or patient survival and was not associated with proteinuria or occurrence of UTIs. Patients with VUR had a lower eGFR at 1 year after transplantation than did patients without VUR (60 vs. 52 mL/min/1.73 m(2) ; p = 0.02), although this difference was not observed at 3 and 5 years after transplantation. We conclude that early VUR, a common finding among renal transplant patients, may not have a meaningful impact on long-term transplant outcomes.

Endourological management of ureteric strictures after kidney transplantation: Stenting the stent

The incidence of ureteric obstruction after kidney transplantation is 3–12.4%, and the most common cause is ureteric stenosis. The standard treatment remains open surgical revision, but this is associated with significant morbidity and potential complications. By contrast, endourological approaches such as balloon dilatation of the ureter, ureterotomy or long-term ureteric stenting are minimally invasive treatment alternatives. Here we discuss the available minimally invasive treatment options to treat transplant ureteric strictures, with an emphasis on long-term stenting. Using an example patient, we describe the use of a long-term new-generation ureteric metal stent to treat a transplant ureter where a mesh wire stent had been placed 5 years previously. The mesh wire stent was heavily encrusted throughout, overgrown by urothelium and impossible to remove. Because the patient had several previous surgeries, we first considered endourological solutions. After re-canalising the ureter and mesh wire stent by a minimally invasive procedure, we inserted a Memokath® (PNN Medical, Kvistgaard, Denmark) through the embedded mesh wire stent. This illustrates a novel method for resolving the currently rare but existing problem of ureteric mesh wire stents becoming dysfunctional over time, and for treating complex transplant ureteric strictures.

Retrograde balloon dilation >10 weeks after renal transplantation for transplant ureter stenosis - our experience and review of the literature

Objective

Despite many efforts to prevent ureteric stenosis in a transplanted kidney, this complication occurs in 3–5% of renal transplant recipients. Balloon dilatation (BD) is a possible minimally invasive approach for treatment, but reports to date refer only to the antegrade approach; we analysed our experience with retrograde BD (RBD) and reviewed previous reports.

Patients and methods

From October 2008 to February 2011, eight patients after renal transplantation (RTX) underwent RBD for transplant ureteric stenosis at our hospital. We retrospectively analysed the outcome and reviewed previous reports.

Results

The eight recipients (five men and three women; median age 55 years, range 38–69) were treated with one or two RBDs for transplant ureteric stenosis. There were no complications. The median (range) time after RTX was 4.5 (2.5–11) months. Long-term success was only achieved in one recipient, while five patients were re-operated on (three with a new implant, two by replacement of transplanted ureter with ileum) after a median (range) of 2.8 (0.7–7.0) months after unsuccessful RBD(s). For two recipients the success remained unclear (one graft loss due to other reasons, one result pending). When the first RBD was unsuccessful there was no improvement with a second.

Conclusion

RBD is technically feasible, but our findings and the review of previous reports on antegrade ureteric dilatation suggest that the success rate is low when the ureter is dilated at ⩾10 weeks after RTX. From our results we cannot recommend RBD for transplant ureteric stenosis at ⩾10 weeks after RTX, while previous reports show favourable results of antegrade BD in the initial 3 months after RTX.

Risk factors and treatment success for ureteral obstruction after pediatric renal transplantation

PURPOSE

Risk factors and treatment efficacy for ureteral obstruction following pediatric renal transplantation are poorly understood. We describe a single center experience with pediatric transplant recipients in an effort to discern risk factors and treatment efficacy.

MATERIALS AND METHODS

We retrospectively reviewed the pediatric renal transplant database at our institution from January 1984 to March 2008. Donor and recipient demographics, treatment indications, graft characteristics, surgical techniques, treatment course, complications and graft outcomes were abstracted from clinical records.

RESULTS

A total of 449 children (mean age 8.6 years) who underwent 526 renal transplants were included in the study. Ureteral obstruction requiring intervention developed in 42 cases (8%). Recipient age and gender, recipient and donor race, donor harvest technique, ureterovesical anastomosis with or without stenting, number of donor arteries, number of human leukocyte antigen mismatches, prior renal transplant and ischemia time were not significantly associated with increased incidence of ureteral obstruction. Renal failure secondary to posterior urethral valves was the only parameter significantly associated with increased incidence of ureteral obstruction (univariate OR 4.93, p = <0.0001; multivariate point estimate 7.59, p <0.0001). Of patients with ureteral obstruction 48% presented within 100 days after transplant. Kaplan-Meier analysis showed significantly decreased ureteral obstruction-free survival in patients with vs without posterior urethral valves (log rank test, p <0.0001). Ureteral obstruction, stenting and dilation were not significantly associated with increased graft loss or patient death.

CONCLUSIONS

Ureteral obstruction after renal transplantation in children is a challenging complication that demands clinical vigilance. Posterior urethral valves appear to be a significant risk factor for post-transplant ureteral obstruction likely due to local factors such as ischemia, thick bladder wall and collagen remodeling.

Postrenal transplantation urologic complications

OBJECTIVES

We sought to explore the incidence, risk factors, clinical presentation, management options, and outcomes of post renal transplant urologic complications.

PATIENTS AND METHODS

Between November 1993 and December 2005, we performed 646 renal transplantation procedures in 373 males and 273 females, of whom 81 were children. Kidney grafts were obtained from 461 living and 185 cadaveric donors. The medical records were retrospectively reviewed for urologic complications. Affected patients presented clinically with impaired kidney function: the diagnosis was confirmed by ultrasound scanning, isotope renal scanning, magnetic resonance urography, and/or antegrade urography. Ureteric stricture was managed by percutaneous antegrade ureteric dilatation and stenting, or by surgical reconstruction. Urine leak was treated by prolonged bladder drainage or surgical reconstruction. Renal stones were treated with extracorporeal shockwave lithotripsy.

RESULTS

Urologic complications were detected in 31 recipients (4.8%), including 21 males and 10 females, among whom 4 were children. They had received kidney grafts from 19 living and 12 cadaveric donors. Urologic complications were ureteric strictures in 15 (2.58%), urine leaks in 15 (2.58%), and ureteric stone in 1 (0.17%) recipients. There was no graft loss to urologic complications.

CONCLUSIONS

The incidence of post-kidney transplant urologic complications was 4.8%. They were more common among male recipients and after cadaveric kidney transplantation. Although ureteric stricture presented late posttransplantation and was more common among children (4.23%), urine leak presented early and was more common in the elderly (4.69%). All urologic complications were successfully managed, with no graft loss.

Ureteric lesions detected in normally functioning kidney allografts: risk factors and clinical implications

INTRODUCTION

We characterized the alterations in ureteral biopsies from normally functioning kidney allografts to study risk factors.

MATERIALS AND METHODS

We studied 55 ureteral fragments from kidney grafts obtained during cystoscopy for routine double-J stent extraction. We evaluated the type and severity of the lesions, the risk factors for their occurrence, and their relation to the evolution of the transplant, including the occurrence of renal rejection episodes or ureteral complications.

RESULTS

Borderline or rejection lesions were detected in 21 of the 55 fragments. Rejection lesions were more common among biopsies performed in the first 80 days (54.6%) than during the 120 days afterward (15.4%, P = .043). Similarly, urothelium reactivity was detected in 71.4% and 30.7% of the biopsies performed up to and after 4 months, respectively (P = .008). Urothelial atrophy was detected in 20% of the fragments, the age of the donors being higher in these cases (P = .026). There was a trend to the association of borderline or rejection lesions in the ureteral biopsies and a history of an acute renal rejection episode (P = .053). There were no detectable relations between those findings and the evolution of the transplant.

CONCLUSIONS

Thirty-eight percent of the biopsed ureters showed rejection or borderline lesions, these lesions were more common among biopsies done in the first months after transplantation. These findings are similar to the ones found in routine renal biopsies. We did not find any significant relation between the nature of the lesions encountered on the ureteral biopsies and the evolution of the transplant.