ORIGINAL ARTICLE
Year : 2009 | Volume
: 20 | Issue : 6 | Page : 1005--1009
Urological complications of renal transplantation: Reducing the risk
Jacob A Akoh, Abdu S Opaluwa, David Weller
Directorate of Surgery & Renal Services, Plymouth Hospitals NHS Trust, Derriford Hospital, Plymouth PL6 8DH, United Kingdom
Correspondence Address:
Jacob A Akoh
Consultant General and Transplant Surgeon, Level 04 Derriford Hospital Plymouth PL6, 8DH
United Kingdom
Abstract
Urological complications can have a significant effect on the outcome of renal transplantation including the loss of the graft. The aims of this study were to determine the incidence of urological complications occurring after kidney transplantation at our unit, and how the risk of complications can be reduced. All 398 renal transplantations performed at Derriford Hospital, Plymouth between August 1997 and December 2006 were reviewed. Twenty nine (7.3%) urological complications were noted with a median time to diagnosis of 8.5 days (range 1-950 days) following transplantation; 81% occurring within two weeks. Fourteen (48.3%) of these patients had identifiable risk factors; 10 patients required ureteric reimplantation, 6 had Boari flap reconstruction, and 3 underwent transurethral resection prostatectomy. One graft was lost to severe ureteric necrosis. Steps to reduce the risk of complications include avoiding damage to organs during retrieval, meticulous bench preparation including hydrodilating ureters to exclude ureteric injury and vigilance during the transplant procedure. Prompt and appropriate corrective surgery can diminish the effect of urological complications on graft survival.
How to cite this article:
Akoh JA, Opaluwa AS, Weller D. Urological complications of renal transplantation: Reducing the risk.Saudi J Kidney Dis Transpl 2009;20:1005-1009
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How to cite this URL:
Akoh JA, Opaluwa AS, Weller D. Urological complications of renal transplantation: Reducing the risk. Saudi J Kidney Dis Transpl [serial online] 2009 [cited 2023 Jan 27 ];20:1005-1009
Available from: https://www.sjkdt.org/text.asp?2009/20/6/1005/57254 |
Full Text
Introduction
Since the first successful renal transplantation from one twin to another in 1954, significant improvements in the techniques of renal transplantation and the use of immunosuppressive agents have resulted in better outcomes for renal transplant recipients. Effort is now being concentrated on ways to improve the quality of life of transplant recipients by reducing the complications of immunosuppressive drugs, decreasing post-transplant morbidity and length of stay in hospital, and intervening to prevent early or late graft loss.
Urological complications can have a significant effect on the outcome of renal transplantation and may lead to the loss of the graft. At a time when organ shortage is still the most important factor limiting transplantation with increasing usage of extended criteria kidneys, efforts must be made to maximize the use of these scarce resources.
The aim of this study is to evaluate the incidence of urological complications in consecutive transplants and determine how the risk of urological complications can be lowered.
Patients and Methods
All recipients of kidney transplantation at the South West Transplant Centre (SWTC), Derriford Hospital, Plymouth between August 1997 and December 2006 were included in the study. The patients were identified using the renal computer database (PROTON Information System, Clinical Computing, PLC, London, England). Their discharge summaries were retrieved, and patients who had urological complications were identified. Patients who developed significant urological complications in the allografts were included in the analysis. We entered into proforma sheets and analyzed relevant data that included age, type and date of transplant, and recognized risk factors for urological complications such as skeletonized/stripped ureters, damaged or short ureters, damaged renal arteries/bench surgery, multiple renal arteries, baseline immunosuppression, prolonged cold ischemic time (CIT) greater than 24 hours, and lower urinary tract obstruction and bladder abnormality.
Statistical analysis
The association of risk factors with urological complications was evaluated using Pearson's Chi square test (P≤ 0.05 was regarded as significant). Patients with perirenal collections not compromising renal function, hematuria (not requiring operative intervention) and urinary tract infection were excluded from the study. The duration of follow-up of these patients ranged from 8 to 120 months, with none lost to followup.
Results
A total of 398 renal transplant procedures (355 deceased and 43 living donors) were carried out in 394 patients during the study period with a male to female ratio of 2:1. The mean age of the recipients was 46.2 ± 1.71 compared to 45.5 ± 1.77 (range, 12-75 years) for donors. Urological complications were encountered in 29 (7.3%) patients [Table 1]. Risk factors for urological complications were identified in 14 of 29 patients with complications compared to 24 of 369 who did not develop any urological complications (x 2 = 54.323; P = 0.000). In our series 5 kidneys were reported to have ureteric damage. Four patients had prolonged cold ischemia time (CIT) of greater than 24 hours. Other risk factors included delayed graft function in 2, multiple renal arteries in 2 (one of these had 4 renal arteries with 2 of these transected) and one patient with bladder abnormality who had several reconstructive operations prior to transplantation.
One of the seven patients with a urine leak was the recipient of a living related donor kidney who failed to pass urine after the operation. An ultrasound scan revealed a fluid collection around the transplant and at exploration urine was found to be draining from a freely floating ureter. The gonadal vein, mistaken for the ureter, had been anastomosed to the bladder. Another patient leaked urine from an unrecognized cut to the renal pelvis. Fifty percent of the complications were diagnosed during the first and 31% in the second week. The procedures used in treating the 29 patients with complications are shown in [Table 2]. The only case of graft loss due to urological complication in this series resulted from extensive necrosis of the ureter extending from the lower end to the anterior portion of the renal pelvis. Of the two patients managed by permanent stenting, one suffered necrosis of the lower transplant ureter, but had an adequate length of a well vasculized ureter to allow re-implantation; this was complicated by a stricture. Further attempts at corrective surgery were deemed too hazardous. A stent was inserted during a combined antegrade and retrograde approach. The second patient developed a stricture 2 years post transplant. Following a failed attempt to dissect the ureter due to severe fibrotic adhesions, a stent was inserted with a plan to change every 4-6 months.
Discussion
The 7.3% incidence of urological complications reported in our study compares favorably with 2.9 to 21% reported in large series. [1],[2],[3],[4],[5] It is noteworthy that 81% of the complications occurred within the first 2 weeks of transplantation. Vigilance and methodical assessment of post transplant patients are essential in order to identify correctable causes of graft dysfunction at any point in the survival curve.
Our study shows that urological complications are more likely to develop in patients with recognized risk factors. However, given the number of transplants and the variety and numbers of risk factors seen, it is difficult to determine whether there are any independent risk factors in our study. Reek et al [1] identified two major etiological factors responsible for urinary leak and early ureteric obstruction to be technical (poor techniques of organ retrieval and ureteric re-implantation) and ureteric ischemia. Injury du-ring retrieval was reported in 1726 of 9014 (19%-7% vascular, 12% non vascular) retrieved kidneys in the UK. [6] Both the vascular and non vascular injuries contribute to the risk of urological complications.
We are not aware of any previous reports of failure to anastomose the ureter, and advocate that the gonadal vein, which serves as a useful anatomical guide to the renal vein during living donor nephrectomy, should be ligated and divided close to the renal vein. This case also high lights the need for vigilance throughout the entire transplant procedure. The preferred method of uretero-neocystostomy in our centre was the extravesical technique with stenting when indicated. This is in agreement with Butterworth et al [7] who reported that both stented and non stented extravesical technique were associated with a lower complication rate than the LeadbetterPolitano technique for vesico-ureteric anastomosis.
Though ureteric necrosis was said to be rare in some reports, 5 were recorded in our study. Emiroglu et al [8] experienced 6/1275 patients with distal ureteric necroses. They all required ureteric re-implantation for restoration of function as in our patients. Ureteric ischemia may be due to denudation of the fragile arterial supply to the ureter. In the retroperitoneal position, the ureter receives segmental blood supply from the renal, common iliac, middle rectal, gonadal, superior and inferior vesical arteries. These arteries anastomose with each other in the adventitia. Following kidney retrieval and transplantation, the ureter depends on the renal artery or arteries until a new vascularization from the vesicular arteries is established. This tenuous blood supply makes the transplant ureter, particularly the lower end, vulnerable to the effects of ischemia-stenosis/stricture and necrosis, the commonest complications observed in our patients. Acute rejection reaction can also cause ischemia of the ureter. [9] Minnee et al [10] identified acute rejection and delayed graft function as the only independent risk factors for a urological complication. Furthermore, Karam et al [11] analyzed the course of 1629 kidney transplants and showed that the independent risk factors for ureteric necrosis included donor age, delayed graft function, cytomegalovirus, high dose steroids and short ureteric length. Our experience of one graft loss in a patient with necrosis of the ureter is similar to that of Chmura et al. [5] Great care should be exercised during retrieval and bench preparation of the donor kidney to preserve its tenuous arterial blood supply.
Complete obstruction of the renal artery resulting in total renal infarction has been reported in patients with fibromuscular dysplasia, [12] which tends to affect the mid or distal renal artery and may result in stenosis of a branch renal artery. Moreover, CsA is known to cause chronic fibrosis due to its ability to increase the production of transforming growth factor β1 . [13]
Stented ureteric re-implantation is often sufficient to treat urine leaks and anastomotic stenosis of the lower ureter. However, in the presence of necrosis or a long stricture of the transplant ureter, the challenge remains to ensure an adequate length of well vascularised ureter to anastomose to the bladder. Although the native ureter can be used to provide a tension free conduit from the residual transplant ureter to the bladder, frequently this requires mobilization of the native ureter with the attendant risk of stricture of the uretero-ureteric anastomosis. Due to its rich blood supply, a pedicled flap of bladder wall (Boari flap) can be used to bridge a 10-15 cm defect in the ureter without tension. [14] A flap length to breadth ratio of 3:1 will ensure the apex is well vascularised. During the mobilization of the ureter, care is taken to preserve its adventitia. The ureter is spatulated and anastomosed to the flap ensuring that the anastomosis is free of tension and watertight. Tension-free anastomosis is important to avoid stricture, the most common complication in Boari flap reconstruction. One of our patients who had ureteric necrosis received a kidney with a damaged arterial patch. In the United Kingdom, marginal or suboptimal donors account for about 30% of kidneys transplanted, [15] and will continue as a source for the ever increasing demand for organs.
Symptoms in patients with lower urinary tract obstruction manifest usually after renal transplantation. This is not unexpected because most patients with chronic renal failure pass little or no urine. There is no agreement with regard to the timing of evaluation and surgical intervention of patients with bladder outlet obstruction (BOO) undergoing renal transplantation. Instrumentation prior to transplantation may predispose patients to urethral strictures. [2] Some advocate early intervention following renal transplantation. Streeter et al [2] reported that only 2% of patients with lower urinary tract obstruction are likely to require surgical intervention within 6 months after transplantation. Three patients in our study who required transurethral resection of the prostate (TURP) had their procedures within 6 months of renal transplantation. It is still controversial whether to evaluate the lower urinary tract of asymptomatic patients before transplantation in order to avoid or reduce symptomatic bladder outlet obstruction (BOO) after surgery. Given the low incidence of BOO (1.3% in our study), such a practice would not be cost effective.
In conclusion, our analysis shows that patients with risk factors are more likely to develop urological complications. We can reduce the risk of these complications by avoidance of damage to organs during retrieval, meticulous bench preparation including hydrodilating ureters to exclude lacerations, and vigilance throughout the entire transplant procedure. Furthermore, early diagnosis and prompt and appropriate corrective surgery can diminish the effect of complications on graft function and prevent graft loss.
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