Evaluation of the Effectiveness of Interventions on Nephrolithiasis in Transplanted Kidney

Renal transplant nephrolithiasis: Presentation, management and follow-up with control comparisons

Objectives

To analyse the presentation, management and long-term outcomes of renal transplant patients who formed kidney stones in their allograft. The secondary aim was to identify risk factors for stone formation in this cohort.

Materials and Methods

Patient information from an institutional renal transplant database was used to identify individuals who both did and did not form kidney stones following renal transplantation. Computerized tomography (CT) imaging was used to make the diagnosis of kidney stones and measure stone size. Age- and gender-matched controls never forming a stone in their allograft were used for comparative analysis to identify risk factors for stone formation in transplant patients.

Results

A total of 8835 transplant patients were included in the study, of which 128 (1.4%) formed a kidney stone in their allograft after surgery. The mean time to kidney stone identification was 6.2 years, and the mean number of stones formed was 1.7, with a mean maximum size dimension on a CT scan of 5.7 mm per stone. A total of 26 patients were subjected to stone-removing procedures, the most common being ureteroscopy (42.3%). The primary intervention failed in eight patients requiring a secondary intervention, and percutaneous nephrolithotomy (PCNL) had the lowest success rate (60%). A total of 164 controls were identified. In comparison to controls, stone formers had lower serum calcium (p = 0.008), lower estimated glomerular filtration rates (p = 0.019), higher lymphocyte counts (p = 0.021) and greater rate of urinary tract infection (p = 0.003). Graft failure rates were the same (p = 0.524), but time to graft failure was significantly longer in stone patients compared with controls (p = 0.008).

Conclusions

The rate of stone formation is low in transplant patients. Success rates for stone treatment vary based on the surgery selected, with PCNL being the worst. Graft survival rates were equivocal, but survival time was better in stone patients. Our analysis calls for further investigation of this important topic.

Evaluating the safety of bariatric surgery as a bridge to kidney transplant: a retrospective cohort study

BACKGROUND

Bariatric surgery has been proven safe in end-stage kidney disease (ESKD); however, few studies have evaluated whether a history of bariatric surgery impacts transplant-specific outcomes. We hypothesize that a history of bariatric surgery at the time of transplant does not adversely impact transplant-specific outcomes.

METHODS

The IBM MarketScan Commercial Claims and Encounters database was queried for patients with a history of kidney transplant between 2000 and 2021. Patients were stratified into three groups based on bariatric surgery status and body mass index (BMI) at the time of transplant: patients with obesity (O), patients without obesity (NO), and patients with a history of bariatric surgery (BS). Inverse probability of treatment weighting was used to control for confounding. Adjusted hazard ratios (aHRs) describing the risk of transplant-specific and postoperative outcomes were estimated using weighted Kaplan-Meier curves. Primary outcomes included 30-day and 1-year risk of transplant-specific outcomes. Secondary outcomes included 30-day and 1-year postoperative complications and 30-day and 1-year risk of wound-related complications.

RESULTS

We identified 14,806 patients; 128 in the BS group, 1572 in the O group, and 13,106 in the NO group. There was no difference in 30-day or 1-year risk of transplant-specific complications between the BS and NO group or the O and NO group. Patients with obesity (O) were more likely to experience wound infection (aHR 1.49, 95% CI 1.12-1.99), wound dehiscence (aHR 2.2, 95% CI 1.5-3.2), and minor reoperation (aHR 1.52, 95% CI 1.23-1.89) at 1 year. BS patients had increased risk of wound infection at 1 year (aHR 2.79, 95% CI 1.26-6.16), but were without increase in risk of minor or major reoperation.

CONCLUSION

A history of bariatric surgery does not adversely affect transplant-specific outcomes after kidney transplant. Bariatric surgery can be safely utilized to improve the transplant candidacy of patients with obesity with CKD and ESKD.

Successful percutaneous nephrolithotomy in patient with ipsilateral dual kidney transplant, a case report

Percutaneous Nephrolithotomy is a minimally-invasive procedure used in the setting of complex stone burden. Among its uses, PCNL can be employed to treated renal allograft calculi. This case presented a unique challenge and a rare usage of PCNL that involved removal of a 2.6 cm stone that presented in a 43-year-old male with dual renal allografts. The unique location of the allograft presented challenges that were navigated successfully with an uneventful postoperative course and no residual stone burden. The utilization of PCNL to treat calculi in dual renal allografts has been minimally reported in the literature.

A case of a transplanted kidney with an orthotopic kidney stone

A 39-year-old man was admitted to our hospital with kidney stones after kidney transplantation. Kidney, ureter, and bladder radiographs showed multiple stones in the transplanted and orthotopic kidneys, which had not been reported previously. Owing to the larger size of the stones in the transplanted kidney, they needed to be removed. Percutaneous nephrolithotomy and ureteroscopy were performed under B-mode ultrasound guidance. The stone measured 1.9 × 1.6 cm and was located under the calyx of the kidney. A titanium laser fiber was used to dissolve the stones, which were subsequently removed. No adverse reactions occurred during or after the surgery. The causes of stone formation included dietary factors, related drugs, improper fluid intake, and urinary tract infections. As neither the donor nor the recipient had a history of kidney stones, we hypothesized that the stones were a new entity that either developed following transplantation or a long-term complication.

Percutaneous nephrolithotomy for adult renal transplant de novo graft lithiasis: a single center analysis and systematic review of the literature

INTRODUCTION/OBJECTIVE

Graft stones in renal transplant recipients pose a unique challenge, finding effective interventions to ensure optimal graft function and patient well-being. Various methods of stone clearance have been described for graft stones, including percutaneous nephrolithotomy (PCNL). While PCNL is a promising approach for managing graft stones, specific outcomes and associated characteristics for this approach have not been comprehensively evaluated before. This study aims to evaluate the safety and efficacy of the use of PCNL as the primary intervention of graft stones by assessing stone-free rates (SFR), treatment impact on graft function, and perioperative complications.

METHODS

A retrospective clinical audit was performed for all transplants performed in a single center from 2007 to 2022, which included all graft lithiasis patients who were treated with PCNL. Both perioperative parameters and post-operative outcomes were collected. In addition, a systematic review including articles from MEDLINE, Embase, Web of Science yielded 18 full-text articles published between 1/1/2000 and 15/11/2023. The results pertaining to patients who underwent PCNLs for graft stones were cross-referenced and thoroughly evaluated. The review encompassed a comprehensive analysis of clinical data, postoperative outcomes, and procedural details. The protocol for the systematic review was prospectively registered on PROSPERO (CRD42023486825).

RESULTS

In our center, 6 graft lithiasis patients were treated with PCNL. The initial SFR was 83.3%. SFR at 3 months and 1 year were both 100.0%. SFR at 3 years was 66.7%. Other centers reported initial SFR of 82.6-100.0% (interquartile range). SFR at 3 months, 1 year, 3 years was not well reported across the included studies. Incidence of graft lithiasis ranged from 0.44%-2.41%. Most common presentations at diagnosis were oliguria/anuria/acute kidney injury and asymptomatic. Reported complications included blood loss, transient hematuria, high urine output, sepsis, and damage to surrounding structures. The most commonly reported metabolic abnormalities in transplant lithiasis patients included hyperuricemia and hyperparathyroidism.

CONCLUSION

PCNL is a practical and efficient choice for addressing graft lithiasis, demonstrating excellent stone clearance and minimal perioperative complications. These findings show the importance of PCNL as a primary intervention in this complex patient population.

URS for de-novo urolithiasis after kidney transplantation: a systematic review of the literature

INTRODUCTION

There is a gap in the available literature and guidelines concerning the optimal approach for treating allograft stones, which currently include external shockwave lithotripsy, ureteroscopy and laser lithotripsy, or percutaneous nephrolithotomy. The objective of this systematic review was to evaluate the safety and effectiveness of URS as a treatment option for patients in this scenario.

EVIDENCE ACQUISITION

A comprehensive search of the literature was conducted until August 2023. Only original articles written in English were considered for inclusion. This review has been registered in PROSPERO (registration number CRD42023451154).

EVIDENCE SYNTHESIS

Eleven articles were included (122 patients). The mean age was 46.9±9.5 years, with a male-to-female ratio of 62:49. The preferred ureteral reimplantation technique was the Lich-Gregoire. The mean onset time was 48.24 months. Acute kidney injury, urinary tract infections and fever were the most frequent clinical presentations (18.3% each), followed by hematuria (10%). The mean stone size measured 9.84 mm (±2.42 mm). Flexible URS was preferred over semirigid URS. The stone-free rate stood at 83.35%, while the overall complication rate was 13.93%, with six (4.9%) major complications reported. Stones were mainly composed of calcium oxalate (42.6%) or uric acid (14.8%). Over an average follow-up period of 30.2 months, the recurrence rate was 2.46%. No significant changes in renal function or allograft loss were reported.

CONCLUSIONS

URS remains an efficient choice for addressing de-novo allograft urolithiasis, offering the advantage of treating urinary stones with a good SFR and a low incidence of complications. Procedures should be performed in an Endourology referral center.

Management of de novo nephrolithiasis after kidney transplantation: a comprehensive review from the European Renal Association CKD-MBD working group

The lifetime incidence of kidney stones is 6%-12% in the general population. Nephrolithiasis is a known cause of acute and chronic kidney injury, mediated via obstructive uropathy or crystal-induced nephropathy, and several modifiable and non-modifiable genetic and lifestyle causes have been described. Evidence for epidemiology and management of nephrolithiasis after kidney transplantation is limited by a low number of publications, small study sizes and short observational periods. Denervation of the kidney and ureter graft greatly reduces symptomatology of kidney stones in transplant recipients, which may contribute to a considerable underdiagnosis. Thus, reported prevalence rates of 1%-2% after kidney transplantation and the lack of adverse effects on allograft function and survival should be interpreted with caution. In this narrative review we summarize current state-of-the-art knowledge regarding epidemiology, clinical presentation, diagnosis, prevention and therapy of nephrolithiasis after kidney transplantation, including management of asymptomatic stone disease in kidney donors. Our aim is to strengthen clinical nephrologists who treat kidney transplant recipients in informed decision-making regarding management of kidney stones. Available evidence, supporting both surgical and medical treatment and prevention of kidney stones, is presented and critically discussed. The specific anatomy of the transplanted kidney and urinary tract requires deviation from established interventional approaches for nephrolithiasis in native kidneys. Also, pharmacological and lifestyle changes may need adaptation to the specific situation of kidney transplant recipients. Finally, we point out current knowledge gaps and the need for additional evidence from future studies.

Kidney stones in renal transplant recipients: A systematic review

INTRODUCTION

Lithiasis in renal graft recipients might be a dangerous condition with a potential risk of organ function impairment.

EVIDENCE ACQUISITION

A systematic literature search was conducted through February 2023. The primary objective was to assess the incidence of lithiasis in kidney transplant (KT) recipients. The secondary objective was to assess the timing of stone formation, localization and composition of stones, possible treatment options, and the incidence of graft loss.

EVIDENCE SYNTHESIS

A total of 41 non-randomized studies comprising 699 patients met our inclusion criteria. The age at lithiasis diagnosis ranged between 29-53 years. Incidence of urolithiasis ranged from 0.1-6.3%, usually diagnosed after 12 months from KT. Most of the stones were diagnosed in the calyces or in the pelvis. Calcium oxalate composition was the most frequent. Different treatment strategies were considered, namely active surveillance, ureteroscopy, percutaneous/combined approach, or open surgery. 15.73% of patients were submitted to extracorporeal shock wave lithotripsy (ESWL), while 26.75% underwent endoscopic lithotripsy or stone extraction. 18.03% of patients underwent percutaneous nephrolithotomy whilst 3.14% to a combined approach. Surgical lithotomy was performed in 5.01% of the cases. Global stone-free rate was around 80%.

CONCLUSIONS

Lithiasis in kidney transplant is a rare condition usually diagnosed after one year after surgery and mostly located in the calyces and renal pelvis, more frequently of calcium oxalate composition. Each of the active treatments is associated with good results in terms of stone-free rate, thus the surgical technique should be chosen according to the patient's characteristics and surgeon preferences.

Shockwave Lithotripsy for De-Novo Urolithiasis after Kidney Transplantation: A Systematic Review of the Literature

BACKGROUND

Allograft urolithiasis is an uncommon, challenging, and potentially dangerous clinical problem. Treatment of allograft stones includes external shockwave lithotripsy (SWL), flexible ureteroscopy and lasertripsy (fURSL), or percutaneous nephrolithotomy (PCNL). A gap in the literature and guidelines exists regarding the treatment of patients in this setting. The aim of this systematic review was to collect preoperative and treatment characteristics and evaluate the outcomes of post-transplant SWL for stone disease.

METHODS

A systematic search in the literature was performed, including articles up to March 2023. Only original English articles were selected.

RESULTS

Eight articles (81 patients) were included in the review. Patients were mainly male, with a mean age of 41.9 years (±7.07). The mean stone size was 13.18 mm (±2.28 mm). Stones were predominantly located in the kidney (n = 18, 62%). The overall stone-free rate and complication rates were 81% (range: 50-100%) and 17.2% (14/81), respectively, with only one major complication reported. A pre-operative drainage was placed in eleven (13.5%) patients. Five patients (6.71%) required a second treatment for residual fragments.

CONCLUSIONS

SWL is a safe and effective option to treat de novo stones after transplantation. Larger studies are needed to better address allograft urolithiasis management.