Endourological management of live donors with urolithiasis at the time of donor nephrectomy: a single center experience

Ex Vivo Surgical Removal Versus Conservative Management of Small Asymptomatic Kidney Stones in Living Donors and Long-term Kidney Transplant Outcomes

BACKGROUND

Donors with small asymptomatic kidney stones have been increasingly accepted because of organ shortages and advances in endoscopic urology. This study aims to evaluate and compare long-term living-donor kidney transplant outcomes following ex vivo surgical removal versus conservative management of donors' gifted asymptomatic stones.

METHODS

Between January 2007 and December 2021, 119 kidney transplant recipients received stone-bearing kidneys, divided into the removal group (N = 63) and observation group (N = 56). We evaluated posttransplant stone events, urinary infections, kidney function, delayed graft function, length of hospital stay, and survival outcomes.

RESULTS

After a median follow-up of 75.5 mo, the removal group had a 10.9% lower absolute incidence of stone events (7/56 [12.5%] versus 1/63 [1.6%]; hazard ratio, 0.08; 95% confidence interval, 0.01-0.77) and a 14.3% lower absolute incidence of urinary infections (16/56 [28.6%] versus 9/63 [14.3%]; hazard ratio, 0.42; 95% confidence interval, 0.19-0.95) than the observation group. The removal group also showed superior kidney graft function. The 2 groups had comparable length of hospital stay (11.0 versus 12.0 d; P = 0.297) and exhibited similar delayed graft function incidence (1/56 [1.8%] versus 2/63 [3.2%]; P = 1.000) and urinary stricture incidence (1/56 [1.8%] versus 3/63 [4.8%]; P = 0.621). Graft survival (P = 0.350) and patient survival (P = 0.260) were comparable between 2 groups. Subgroup analyses in recipients who received kidneys with stones <4 mm also reported similar results.

CONCLUSIONS

Ex vivo surgical removal might outperform conservative management for donors' gifted asymptomatic kidney stones, improving long-term transplant outcomes and reducing stone events without increasing perioperative complications, even for stones <4 mm.

Radiologic evaluation of the kidney transplant donor and recipient

The kidney is the most common solid organ transplant globally and rates continue to climb, driven by the increasing prevalence of end stage renal disease (ESRD). Compounded by advancements in surgical techniques and immunosuppression leading to longer graft survival, radiologists evermore commonly evaluate kidney transplant patients and candidates, underscoring their role along the transplant process. Multiphase computed tomography (CT) with multiplanar and 3D reformatting is the primary method for evaluating renal donor candidates, detailing renal size, vascular/collecting system anatomy, and identifying significant pathologies such as renal vascular diseases and nephrolithiasis. Ultrasound is the preferred initial postoperative imaging modality for graft evaluation due to its low cost, accessibility, noninvasiveness, and lack of radiation. CT and magnetic resonance imaging (MRI) may be useful adjunctive imaging techniques in diagnosing transplant pathology when ultrasound alone is not diagnostic. Kidney transplant complications are categorized by an approximate timeline framework, aiding in differential diagnosis based on onset, duration, and severity and include perinephric fluid collections, graft compression, iatrogenic injuries, vascular compromise, graft rejection, and neoplastic processes. This review discusses imaging strategies and important findings along the transplant timeline, from donor assessment to long-term recipient complications.

Current Perspectives on Endourological Ex Vivo Stone Interventions in Kidney Transplantation: A Systematic Review

OBJECTIVE

To conduct a systematic review (SR) of literature to assess the existing evidence concerning the success and complications of endourological ex vivo stone surgeries.

METHODS

Eligible studies for inclusion focused on investigating the success and/or complications related to endourological ex vivo surgeries in donors with nephrolithiasis. A SR was undertaken in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The search included databases of Web of Science, PubMed, and Scopus and only article in English were included. Studies published between 2002 and 2023 included in this SR.

RESULTS

After screening 1726 abstracts, this SR included 16 studies with a total of 209 patients. The mean stone size was 5.6 mm and majority of kidneys contained single stones, located in the lower calyx. After ex vivo endourological stone surgeries, the average stone-free rate was found to be 95.4%. The mean duration of ex vivo surgery was 17.3 minutes. Regarding intraoperative complications, two patients (1%) experienced mucosal injuries during pneumatic lithotripsy. As for postoperative complications, two patients (1%) experienced vascular complications. In terms of urological complications, hematuria was observed in 24 patients (11.5%), while one patient (0.5%) experienced clot formation in renal pelvis. Seven patients (3.3%) had urinary tract infections, and three patients (1.4%) developed urolithiasis during the follow-up. Additionally, one patient (0.5%) experienced complete occlusion of ureteroneocystostomy and required revision.

CONCLUSION

Given the advancements in current technology and techniques, endourological ex vivo stone surgeries are increasingly recognized as an effective and safe option for donors with nephrolithiasis.

TRIAL REGISTRATION

This systematic review was registered under the protocol registration number CRD42024538384/PROSPERO.

Treatment of donors' asymptomatic small kidney stones and post-transplant outcomes: a meta-analysis

Kidney donors with asymptomatic small kidney stones were increasingly accepted in kidney transplantation (KT) due to organ shortage and advances in endoscopic urology. However, recipients' clinical outcomes using these donors remained unclear. We conducted a meta-analysis to summarize transplant outcomes using these donors with asymptomatic small kidney stones. Finally, 15 retrospective studies were included. The prevalence of asymptomatic small kidney stones was 5.3% (95%CI 3.5-7.8%). After transplantation, low incidence of urinary fistula (0%, 95%CI 0-1.0%), obstruction (0%, 95%CI 0-1.1%), relapse of kidney graft stone (0.3%, 95%CI 0-2.5%), and delayed graft function (0.6%, 95%CI 0-3.5%) was reported. Pooled serum creatinine was 1.3 (95%CI 1.2-1.5) mg/dl and 1.4 (95%CI 1.2-1.6) mg/dl at post-transplant 1 month and 1 year, respectively. Notably, we observed numerically higher relapse rate after conservative management (1.8% [0-9.2%] vs 0% [0-1.8%]) but numerically higher DGF rate after surgical removal of asymptomatic stones (1.8% [0-7.0%] vs 0% [0-1.9%]). Overall, short-term transplant outcomes using kidneys with asymptomatic small stones were acceptable. However, long-term transplant outcomes remained unexplored. Well-designed prospective studies are also needed to compare the efficacy of conservative management with surgical removal of "donors' gifted" asymptomatic kidney stones.

Living donor-gifted allograft lithiasis: surgical experience after bench surgery stone removal and follow-up

This study presents the surgical experience and long-term outcomes of living donor kidney transplantations involving asymptomatic kidney stones, using ex vivo flexible ureterorenoscopy (f-URS) during bench surgery for stone removal. Out of 1743 living kidney donors assessed between January 2012 and October 2022, 18 (1%) were diagnosed with urolithiasis. Among them, 12 donors were rejected, and 6 were accepted for kidney donation. Stone removal was successfully performed using f-URS during bench surgery, with no immediate complications or acute rejections observed. The study analyzed six living kidney transplants, of which 4 (67%) donors and three recipients were female, and 4 (67%) donors were blood-related to the recipient. The median age for donors and recipients was 57.5 and 51.5 years, respectively. The stones, primarily located in the lower calyx, had a median size of 6 mm. The median cold ischemia time during surgery was 41.6 min, and ex vivo f-URS ensured complete stone removal in all cases. After a median follow-up of 120 months, the remaining grafts were functioning well, and no urinary stone recurrence was observed in either the recipients or living donors. The findings suggest that bench f-URS is a safe approach for managing urinary stones in kidney grafts, providing good functional outcomes without stone recurrence in selected cases.

Donor kidney lithiasis and back-table endoscopy: a successful combination

INTRODUCTION

Urolithiasis in renal allografts is relatively rare with an incidence of 0.17-4.40%. It is nonetheless an important issue, as there is a risk of obstruction, sepsis and even loss of the renal allograft. The management of stones in renal allografts remains challenging because of the anatomy, the renal denervation and the use of immunosuppressive medication.

CASE PRESENTATION

This report discusses the ex-vivo treatment of asymptomatic nephrolithiasis in a living donor kidney allograft. A CT abdomen revealed a lower pole stone (5.9 × 5.5 × 5.0 mm; 920 HU) in the right kidney of the potential donor. After multidisciplinary discussion, it was decided to procure the right kidney despite the presence of a documented nephrolithiasis. After discussion with both donor and recipient, an ex-vivo flexible ureterorenoscopy for stone removal on the back table just before implantation of the allograft was planned. The stone was found in the lower pole covered by a thin film of the urothelium. The thin film of urothelium was opened with a laser and the stone fragments were retrieved with a basket. CT after one month showed no residual stones in the transplanted kidney.

CONCLUSION

Back-table endoscopy in a renal allograft is a feasible technique and should be discussed as an option in case of urolithiasis in a kidney that is considered for transplantation. Furthermore, the appropriate treatment of donor kidney lithiasis is another, although rare, method to expand the living donor renal allograft pool.

Outcomes of live renal donors with a history of nephrolithiasis; A systematic review

The clinical outcomes of kidney donors with a prior history of nephrolithiasis are poorly defined. We conducted a systematic review assessing the post-donation clinical outcomes of kidney donors with a history of nephrolithiasis. Electronic databases (Ovid and Embase) were searched between 1960 and 2021 using key terms and Medical Subject Headings (MeSH) - nephrolithiasis, renal stones, renal transplantation and renal graft. Articles included conference proceedings and journal articles and were not excluded based on patient numbers. Primary outcome was donor stone-related event. Secondary outcomes were renal function upon follow-up or post-operative nephrectomy complications. In summary, 340 articles were identified through database search. We identified 14 studies (16 cohorts) comprising 432 live donors followed up for a median of 26 months post live kidney donation. Six donors donated the stone-free kidney whilst 23 live donors had bilateral stones. Mean stone size was 4.2 ± 1.4 mm (1-16) with average follow up duration of 21.1 months (1-149). Twelve studies provided primary outcome (n = 138 patients) and eight (n = 348) for secondary outcomes. One donor had a stone-related event upon follow up. A total of 195 patients had eGFR <60 upon follow up. However, they were not significantly different when compared to renal function of live donors that didn't have pre-donation nephrolithiasis. Many of the studies couldn't provide long term follow up, coupled with limited data regarding the nature of the pre-donation stone disease. In conclusion, this systematic review shows that we have very limited information upon which to base recommendation regarding pre-donation risk of post-donation complications. Longer term follow up is required and lifelong follow up with live donor registries will aid further understanding.

Living Donor Gifted Lithiasis: Long-Term Outcomes in Recipients

OBJECTIVES

Presence of nephrolithiasis in a living donor has been at least a relative contraindication to living donor nephrectomy. The concern for stone recurrence and outcomes has been one of the reasons for reluctance to consider these medically complex donors. We evaluate long-term outcomes in recipients of kidney grafts from donors with nephrolithiasis, or history of nephrolithiasis, and provide results from our experience at Indiana University.

MATERIALS AND METHODS

We retrospectively reviewed 57 donor-recipient pairs, where the allograft was received from a living donor with symptomatic calculi, or with imaging evidence of kidney stones, between 2003 and 2018. This research study was done in compliance with the ethical standards set forth in the Helsinki Congress.

RESULTS

The mean age of recipients was 46±19 years and 58% were male. Kidney recipients were followed for a median of 3.5 years and 59.6% of patients had follow-up imaging studies. None of the recipients had obstructing renal calculi or related infections. None of the recipients required any interventions for recurrent calculi and no stone episode lead to adverse event to the graft. Hyperoxaluria and hypercalciuria were the most common risk factors in 24-hour urine collections obtained from donors.

CONCLUSIONS

Our findings from a single large center looking at kidney recipient outcomes over a long follow-up period found that gifted lithiasis is a safe procedure. Careful selection of "medically complex donors" with kidney stones based on appropriate guidelines is a key step. Further studies are needed to help develop consensus guidelines.

Outcomes of Renal Stone Surgery Performed Either as Predonation or Ex Vivo Bench Procedure in Renal Grafts from Living Donors: A Systematic Review

AIMS

We aimed to summarize available evidence about intraoperative and postoperative donors' and recipients' outcomes following stone surgery in renal grafts from living donors performed either before donation or as ex vivo bench surgery at the time of living-donor nephrectomy.

METHODS

A systematic review of PubMed, ISI Web of Knowledge, and Scopus databases was performed in September 2020. We included full papers that met the following criteria: original research, English language, human studies, and describing the results of stone surgery in renal grafts from living donors performed either before transplantation or as ex vivo bench surgery.

RESULTS

We identified 11 studies involving 106 patients aged between 22 and 72 years. Predonation and bench stone surgery was performed in 9 (8.5%) and 96 (90.6%) patients, respectively. Predonation stone surgery involved extracorporeal shock wave lithotripsy, retrograde intrarenal surgery, and percutaneous nephrolithotomy in 8, 1, and 1 patient, respectively. The overall success rate of predonation stone surgery was 78%, and the complication rate was 0%. Bench stone surgery involved ureteroscopy, pyelolithotomy, or a combination of both in 79 (82.3%), 10 (10.4%), and 7 (7.3%) cases, respectively, with an overall success rate of 95.8% and an overall complication rate of 9.37%.

CONCLUSIONS

Predonation and bench stone surgery in grafts from living donors represents efficacious and safe procedures. Further studies on wider series with a longer follow-up are required.

Intra-operative Postperfusion Micronephrolithotomy for Renal Allograft Lithiasis: A Case Report

Increasing demand drives the expansion of criteria for kidney donation, and nephrolithiasis is now considered a relative contraindication. We report for the first time a case of intra-operative, postperfusion kidney allograft micronephrolithotomy. A 64-year-old man with end-stage renal disease secondary to Alport syndrome underwent primary deceased donor kidney transplantation at our center. Pre-operative ultrasound of the donor identified a 7-mm calculus in the anterior, lower pole calyx. The kidney was extra-peritoneally implanted in the right iliac fossa and reperfused homogenously. Stone retrieval with a flexible ureteroscope failed due to the narrow calyceal infundibulum. Instead, the calculus was removed using the micropercutaneous nephrolithotomy system under ultrasonographic guidance. The calyx was punctured using a 4.85 Fr needle and the stone was fragmented to dust using a Holmium laser. No bleeding was observed. The post-operative course was uneventful. Outpatient follow up demonstrated good function of the graft which was stone free on ultrasound. Postperfusion micropercutaneous nephrolithotomy for kidney allograft calculi offers a safe and feasible option when pre-operative or intra-operative retrograde intrarenal surgery fails.