Does the Presence of Renal Vascular Variation in the Renal Allograft Determine the Outcome of Renal Transplantation? Experience from the National Kidney Transplantation Center, Ethiopia

Background: Renal transplantation is the treatment of choice for people who suffer from end stage renal disease. Renal vascular anatomy is known for presenting a wide range of variations. Kidneys with variant renal vascular anatomy when used as a graft appear to be a potential risk factor that could impair the outcome of kidney transplantation. Information on renal vascular variations and its implication in the surgical outcome of renal transplantation has not been well studied. Hence, the present study was aimed to evaluate the outcomes of transplantation of renal allografts with variant renal vasculature as compared to allografts without renal vascular variation in the national kidney transplantation center of Ethiopia. Methods: A health institution based cross-sectional study was conducted. A retrospective review of the medical records of kidney recipients was performed. A total of 120 renal transplant recipient’s medical records were evaluated. Chi-square test and Independent t test was used to compare the surgical outcomes of renal transplantation. Graft survival was expressed using Kaplan-Meier curves, and was compared using the log-rank test. P values less than 0.05 was considered as statistically signicant. Result: Evaluation of the renal transplant outcomes did not have shown a signicant difference in the postoperative complication rate, rate of delayed graft function (DGF), creatinine clearance levels at 1 , 6, or 12 months postoperatively, and 1-year graft survival among recipients of allografts with and without renal vascular variations. However, operation time and the length of hospital stay were signicantly longer among recipients of allografts with variant vasculature. Conclusion: No signicant difference was noted in the outcomes of transplantation of renal allografts with and without vascular variations. Hence, renal allografts with vascular variations are safe to be recruited for transplantation as to this study. The study was conducted on the kidney recipients who underwent kidney transplantation from a period of commencement of the rst renal transplantation in on to 2020 the The total number of was 142. had this study was on a total of 120 in transplantation center.


Background
End-stage renal disease (ESRD) is diagnosed when the patient has reached Glomerular ltration rate (GFR) of less than 15 mL/min (1). Renal replacement therapy (RRT) is required for ESRD. Hemodialysis, peritoneal dialysis, and transplantation are the three types of RRT. ESRD patients can be successfully treated with hemodialysis or peritoneal dialysis, but kidney transplantation is by far the best therapeutic choice for the vast majority of ESRD patients (2,3). The operation necessitates extensive preoperative preparation and careful kidney selection. The site for transplanting a kidney is in the iliac fossa of the greater pelvis. The renal artery and vein are joined to the external iliac artery and vein, respectively, and the ureter is sutured into the urinary bladder (4).
Kidneys with variant vasculature are prevalent in the general population (between 18% and 50%).
Worldwide, more than 100,000 kidney transplantations are performed each year (5). Owning the scarcity of donor kidney and the rising frequency of end-stage renal disease (ESRD), there is a global trend toward approving the so-called extended criteria kidney donors. Transplantation of renal allograft with vascular variations necessitates a sophisticated vascular reconstruction and anastomosis. Because renal vascular variations in kidney donors are linked to greater surgical complication rates in both the donor and recipient, recruiting renal allograft with variant vasculature for transplantation is considered as an expanded criterion (6).
Some studies have linked the extensive dissection and back-table reconstruction to an elevated risk that could compromise the renal transplantation outcome (7,8). Besides, transplanting kidneys with arterial and venous variations are thought to have several disadvantages, such as prolonged warm ischemia duration; an increased incidence of acute tubular necrosis, which can increase the risk of acute rejection episodes, prolonged hospitalization; and poorer graft function (7). Consequently, even though kidneys with vascular variation are common in the general population, the kidney with simple vascular anatomy (ideally one artery, one vein) is often chosen for transplantation since the technical components of the process are usually completed without di culties (9)(10)(11). However, there is a dearth of literature that has assessed and reported the outcomes of transplantation of a renal allograft with a variant vasculature in Ethiopia.
In Ethiopia, the rst kidney transplantation took place in 2015 (4). Since then, the practice of kidney transplantation in the country has shown steady expansion and progress (4). Given the rising number of kidney transplantation procedures, and being the variations of renal vascular are is common in the general population, renal allografts with variant vasculature are to be reputed for transplantation.
Otherwise, signi cant number of kidney donors will not be entitled for donating a kidney only for having a variant renal vasculature; this may worse the shortage of a kidney for transplantation. Hence, it has become important at this point to evaluate the outcome of transplantation of a renal allograft with a variant vasculature. The nding of the present study will advance the available information on the association between renal vascular anatomy and its transplantation outcomes.

Materials And Methods
A health institution based cross-sectional study with retrospective record review was conducted at the

Statistical Analysis
The collected data was coded, cleaned, and entered into Epi-data version 4.4 and exported to SPSS version 25 for analysis. Variables were described as frequency, percentages, mean, and standard deviation (SD). Chi-square test was used for comparison of categorical variables whereas Independent ttest for the comparison of continuous variables. Graft survival was expressed using Kaplan-Meier curves, and was compared using the log-rank test. Statistical signi cance was declared at P < 0.05. Results were presented by using tables, gures, and texts.

Baseline characteristics of Kidney Transplantation recipients
Among a total of 120 recipients, 86 (71.6%) were males with a mean age of 33.3 years (SD ± 11.41). 34 (28.3%) recipients received renal allografts with renal vascular variations. Of the 34 recipients who received kidney with variant vasculature, 28 (82.4%) patients received an allograft with renal arterial variation, and 6 (17.6%) patients received an allograft with renal venous variations. With regard to age, sex, and BMI, no signi cant difference (P > 0.05) was noted between groups of patients who received renal allograft with anatomically variant renal vasculature and without (Table 1).  (Fig. 1). Diuresis of the transplanted kidney on the operation table was achieved in 95% of the transplantations and did not signi cantly differed (P > 0.05) based on the renal vascular anatomy; that is, between groups who received allografts with and without variant renal vasculature. Only two of the patients who received allografts without vascular variation and, one patient who received an allograft with vascular variation needed dialysis during the rst postoperative week, this is nearly similar rate between groups. Although not signi cant (P > 0.05), post-operative complications were more frequently reported in patients who received grafts with variant renal vascular anatomy than without. Re-admission and re-operation rates were similar between the groups (Table 2). P-value with "*" shows statistically signi cant variables, "a", "b", "c" represents independent t test, pearson chi-square, and sher exact test, respectively.

Graft survival
Postoperative graft survival was analyzed at 1week, 1 month, 6month and 1 year (Fig. 2). The 1-year graft survival for 86 patients who received grafts without vascular variations was 95.4%, and that for the 34 patients who received grafts with vascular variations was 91.2%. The result exhibited that the variation of renal vascular anatomy is not a determinant for the graft survival (P = 0.378).

Discussion
Evaluation of the renal transplant outcomes did not have shown a signi cant difference in the postoperative complication rate, rate of delayed graft function (DGF), serum creatinine levels at 1, 6, or 12 months postoperatively, and 1-year graft survival among recipients of allografts with and without renal vascular variations. However, operation time and the length of hospital stay were signi cantly longer among recipients of allografts with variant vasculature.
In the present study 34 (28.3%) renal transplantations were performed by using renal allografts with variant vasculature. All the renal allografts (100%) that have been used for the transplantations carried out in the center were left kidneys. The practice of selecting left-sided grafts is not uncommon and has been reported in several studies (12)(13)(14). Furthermore, previous studies have commented on an increased risk of early graft failure with transplanting right-sided renal allografts (15). In contrast, some centers have used a large number of right-sided renal allografts and reported no signi cant difference in graft function (16). The preference of left-sided renal allografts is often due to the longer left renal vein, which makes vascular anastomosis technically easier and also been shown to decrease operating time (16).  (20). Similarly, Kok et al, reported urine production within one hour of reperfusion was 91% for single artery allograft recipients and 92% for multiple artery allograft recipients (p = 0.639) (21).

Post
In the present study, operation time and the length of hospital stay were signi cantly longer among recipients of allografts with variant vasculature. In contrast to this nding, several other studies have reported that operation time and length of hospital stay were shorter and not signi cantly different among recipients of allografts with and without vascular variation (12,20,22). The longer operation time reported in this study is may be due to the open approach of the donor nephrectomy procedure employed in the transplantation center as this procedure is performed simultaneously with the transplantation surgery. Open donor nephrectomy takes longer operation time as compared to laparoscopic nephrectomy (14). Despite a statistically signi cant difference noted in the operation time and length of hospital stay, the clinical impact of these parameters is limited (12). Estimated blood loss, 30 day readmission and reoperation rates were not signi cantly different with the renal vascular variations of the renal allograft, and this nding is supported by many other authors (20)(21)(22)

Conclusion
Transplantation of renal allografts with and without renal vascular variations has comparable outcomes as to the present study. Although operation time and length of hospital stay were signi cantly different between the groups, their clinical relevance is minimal. Hence, renal allografts with vascular variations are safe to be recruited for transplantation, and the entitlement of such allografts will increase the availability of kidneys for renal transplantations. Availability of data and materials All the datasets used and/or analysed during the current study are available from the corresponding author on reasonable request

Competing interests
The authors declare that they have no competing interests Funding The current study was monetarily supported by AMU.