Introduction
Urological problems account for the majority of surgical complications in kidney transplant recipients, occurring at rates of 1–15 percent after transplantation. These issues are a leading cause of patient mortality and morbidity, with far-reaching consequences for graft survival over the course of the graft’s lifetime. Finally, because the transplant includes a significant component of the urinary system, the transplant team must be prepared for both known and unforeseeable urological complications in the short and long term.
Urological problems like urine leakage, ureteral stenosis, and vesicoureteral reflux, bladder outlet obstruction, and graft urolithiasis are the most common. Significant progress has been made in the management of urological problems in recent years, thanks to advancements in endourologic procedures. This article takes a comprehensive look at post-transplant urological diseases. The goal of this review is to synthesise the existing knowledge on the management of urological issues following kidney transplantation.
Postoperative Urological Complications
Urological problems that arise soon after surgery are the leading cause of lengthy hospital stays. Older donor age and a history of cardiac events in the recipient are also predictors of urological problems. Long dialysis times and limited bladder capacity are two further independent risk factors. However, the link between urological problems and living or deceased donor transplants is unknown.
The use of ureteral stenting during surgery has been proven to reduce the rate of urological problems. Intraoperatively, ureteral stents can be implanted as an internal double-J stent or as an exterior (percutaneous) stent. Internal double-J stents, on the other hand, have no agreed-upon dwell period. The goal is to remove the double-J stent as quickly as possible to avoid stent-related problems such as urinary tract infection (UTI). At the same time, this interval must be lengthy enough for the ureterovesical anastomosis to heal completely. When looking at current studies and meta-analyses, a dwell duration of roughly 3 weeks appears to be the most appropriate.
Ureteral Stenosis
With an incidence of between 2 and 13% in different series, ureteral stenosis is one of the most common major urological complications following transplantation. It may occur in the early (<3 months) or late (>3 months) postoperative period. It is primarily attributed to poor surgical technique and ureteral devascularization. Ureteral stenosis often manifests in the early period as ureteral obstruction.
The ischemia most often occurs due to devascularization or BK polyomavirus infection. For this reason, endourologic approaches are usually sufficient for its treatment. For patients who do not respond to minimally invasive methods, the implantation of self-expanding metallic ureteral stents is a safe and effective treatment.
Urine Leakage
Urine leakage is the most prevalent early postoperative urological problem, occurring in 1.5 to 8.9% of cases. It is mainly caused by ischemia necrosis of the ureterovesical anastomosis’s distal ureteral segment. For the treatment of urine leakage, minimally invasive methods should be considered first. Ureteral catheterization, percutaneous nephrostomy, and antegrade or retrograde double-J stent implantation are examples of these procedures.
The primary approach should be urethral catheterization. This permits tiny leaks caused by delayed healing to be repaired. Furthermore, ureteric stenting and percutaneous nephrostomy with urethral catheterization can provide a decisive therapeutic choice when graft performance is closely monitored. The goal of treatment should be to ensure that the urinary tract is decompressed as much as possible.
Due to the danger of subsequent ureteral stricture, which reduces the long-term success of endourologic therapies to about 60%, patients must be constantly monitored after the removal of a double-J stent. If endourologic interventions are not effective, open surgical approaches such as ureteral reimplantation or pyeloureterostomy with the native ureter should be considered.
Vesicoureteral Reflux (VUR)
VUR occurs after kidney transplantation in 2–79% of the cases.The most commonly used ureteroneocystostomy (UNC) technique in transplant surgery is the Lich-Gregoir technique with an extravesical approach. VUR is the most common postoperative urological complication in pediatric kidney transplant recipients and can cause serious morbidity when accompanied by lower urinary tract symptoms (LUTSs).
It should be kept in mind that while the role of urological disorders is up to 60% in the etiology of ESRD in children, this rate is between 1.4 and 5% in adults. Studies published about 2 decades ago implicated VUR as a major factor in late renal graft failure. Endoscopic treatment with submucosal Teflon injection (Sting) is widely used for the treatment of VUR because it is easily performed and is associated with low morbidity.
In brief, the Sting procedure should be the first choice for low-grade symptomatic VUR, for which it has high success rates, while open surgery should be considered for patients with high-grade VUR.
Bladder Outlet Obstruction
Urinary retention due to bladder outlet obstruction (BOO) is a common urological condition that can develop early or late following a kidney transplant, especially in middle-aged and older men. BOO can be caused by a blocked bladder neck or benign prostatic hyperplasia (BPH).
In urinary retention, increased intravesical pressure that forms due to contraction of the detrusor muscle adversely affects graft function. However, identifying these patients before transplantation is a major challenge. It should be known that it is very difficult to predict the incidence of BOO in these patients due to oliguria or anuria resulting from dialysis.
For this reason, in patients who are oliguric or anuric and diagnosed with BPH pretransplantation, it is recommended to perform the operation after transplantation due to the high risk of morbidity. In light of their short- and long-term outcomes, TURP and TUIP also seem to be safe to perform on patients who do not benefit from medical treatment for urinary retention that occurs within the first month after a transplant. A risk of surgery that should be avoided during this period is damage to the ureterovesical anastomosis created during transplantation.
TURP is also an effective solution for the surgical treatment of BPH occurring in the long term after transplantation. TUIP is a TURP alternative especially applicable for the surgical treatment of BOO. Due to the high morbidity rates with TURP, urology guidelines recommend TUIP for small prostate volumes (<30 cm3) and patients at risk of postoperative retrograde ejaculation.
Allograft Urolithiasis
Urinary lithiasis following kidney transplantation is a relatively uncommon urological problem seen in 0.17–1.8% of the cases. Stones in a transplanted kidney present a risk of obstruction, sepsis, and loss of graft function. Due to these potential problems, lithiasis in the donor kidney has been regarded as a relative contraindication to donation.
There are 3 approaches in the management of stones detected in a donor candidate who meets radiological and metabolic criteria.
- Clearance of stones from the donor kidney using retrograde intrarenal surgery or extracorporeal shock wave lithotripsy.
- A single-stage procedure involving ex vivo ureteroscopy/pyelotomy of the donor kidney immediately afternephrectomy (bench surgery).
- Conservative surveillance of stones ≥4 mm with Non-contrast computed tomography.
Options for the management of allograft lithiasis include the conservative approach, extracorporeal shock wave lithotripsy, and endourologic, percutaneous, and open surgical approaches. Minimally invasive approaches such as rigid or flexible ureteroscopic (URS) lithotripsy are currently the most commonly used methods for the treatment of allograft lithiasis.
An important factor in the success of URS is the location of the UNC. The position and orientation of the transplanted ureter may be problematic. As ureter implantations to the anterior aspect or dome of the bladder do not leave a suitable anatomic passage posttransplant, it can be difficult to access the ureter and even the renal graft using standard equipment, which can prolong the operative time.
The posterolateral extravesical UNC method, also referred to as the modified Lich-Gregoir technique, largely solves this problem. This technique has been observed to substantially facilitate retrograde procedures and shorten the operative time.
Conclusion
To summarize the conclusions that can be gleaned from this review, an internal double-J stent should be considered in order to reduce posttransplant urological complications. Conservative follow-up is sufficient for asymptomatic VUR that develops after transplantation in adults. The Sting procedure is an effective treatment solution, especially for low-grade VUR.
In the surgical treatment of BOO, TURP and TUIP can be performed safely both in the first month after transplantation and in the long term. Asymptomatic stones <4 mm in the donor can be followed up conservatively, and transplantation can be performed with the stone-bearing kidney. For stones 4–15 mm in size, ex vivo stone surgery is an effective solution.
For UNC during transplantation, the modified Lich-Gregoir technique offers a major advantage in endourologic approaches to the treatment of posttransplant allograft lithiasis.
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