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Table of Contents
ORIGINAL ARTICLE
Year : 2021  |  Volume : 15  |  Issue : 1  |  Page : 24-28

Renal angiographic evaluation of prospective renal donors: Single-center data and outcome analysis from South India - A retrospective observational study


1 Department of Nephrology, SRIHER, Chennai, Tamil Nadu, India
2 Department of Radiology, SRIHER, Chennai, Tamil Nadu, India

Date of Submission11-Jul-2020
Date of Acceptance22-Nov-2020
Date of Web Publication31-Mar-2021

Correspondence Address:
Dr. Varadharajan Jayaprakash
Department of Nephrology, SRIHER, Porur, Chennai - 600 116, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijot.ijot_77_20

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  Abstract 


Introduction: In countries without a well-developed deceased donor program, living donors form the backbone of the renal replacement strategy. Computed tomography (CT) angiography forms an integral part of the predonation evaluation. The course, number, and morphometric evaluation of the renal vasculature provided by CT angiography help to identify which kidney to harvest and which kidney to exclude from the donation. The characteristics of the Indian renal donor are a rarely studied topic with only a few studies on the same to date. Methodology: This is an observational study done over a period of 3 years noting the clinical and morphometric characteristics of the renal donors from a database. Results: In this study, 57 prospective living renal donors were included. Most donors were women. The length of the renal artery and renal vein was shorter in this cohort than in previously known statistics. The diameter of the renal vessels was also smaller than previous data. The left side kidney was more commonly harvested compared to the right. Conclusion: Renal angiographic morphometric data among the Indian population were different from previously known statistics. Angiographic data correlated well with intraoperative findings in the majority of patients.

Keywords: Computed tomography findings, morphometric analysis, renal angiography, renal donor


How to cite this article:
Jose N, Jayaprakash V, Deiva A, Sai V, Jayakumar M. Renal angiographic evaluation of prospective renal donors: Single-center data and outcome analysis from South India - A retrospective observational study. Indian J Transplant 2021;15:24-8

How to cite this URL:
Jose N, Jayaprakash V, Deiva A, Sai V, Jayakumar M. Renal angiographic evaluation of prospective renal donors: Single-center data and outcome analysis from South India - A retrospective observational study. Indian J Transplant [serial online] 2021 [cited 2021 Jun 16];15:24-8. Available from: https://www.ijtonline.in/text.asp?2021/15/1/24/312758




  Introduction Top


The renal donation has been a boon to the patient with end-stage kidney disease.[1] Choosing the right donors has come to mean a detailed evaluation of the prospective donor pretransplant and prolonged postdonation follow-up. Computed tomography (CT) angiography of the renal vasculature plays a key role in predonation evaluation.[2] This step is crucial since it delineates the donors' vascular anatomy providing information on the length and diameter of renal vessels required for transplant and number of vessels. It also provides information about the morphology of the kidney and collecting system and extrarenal organs. The morphology of renal vasculature among the Indian population has been a less studied area and forms the requirement of the current study. In this study, donor angiographic data were analyzed to profile the renal donors in terms of common anomalies, morphometry, and outcomes of transplant.


  Methodology Top


This was a retrospective observational study done between the periods of January 2017 and January 2020. All prospective renal donors who had undergone preliminary evaluation and planned for the donation were included. The database of the hospital provided the detailed angiographic report and the clinical details of the donors. Fifty-seven potential donors' clinical data were recorded and analyzed along with CT angiographic data using SPSS 17 software (SPSS Inc. Chicago, USA) to yield the results below.

Statistical analysis

All statistical analyses were performed using statistical package for social science SPSS 17 for Microsoft windows. Descriptive statistics was presented as numbers and percentage. Data was expressed as mean and standard deviation. Independent sample t-test was used to compare continuous variables between two groups. A 2-sided p-value <0.05 was considered as statistically significant.

Patient consent

The patient consent has been taken for participation in the study and for publication of clinical details and images. Patients understand that the names, initials would not be published, and all standard protocols will be followed to conceal their identity.

Ethics statement

This project has been approved by the Institution Ethics committee CSP-MED/20/DEC/64/204. All protocols were followed as per Declaration of Helsinki.


  Results Top


[Table 1] shows the baseline characteristics of the study population. The mean age of the population was 45.38 years. Females donated kidneys more often than males (61.4% vs. 38.6%, respectively). Most donors (92.9%) did not have any detected comorbidities after preliminary evaluation for fitness for donation. In donors with comorbidities, the most common comorbidity was hypothyroidism. Baseline renal function evaluation showed a mean creatinine of 0.68 mg/dl. The mean glomerular filtration rate (GFR) measured by Diethylene Triamine Penta-acetic acid (DTPA) was 91.2 ml/min/1.73 m2. Overall, the right kidney appeared to have better function than the left in most patients. Urinalysis was normal in all the donors. The mean 24 h urine protein was 62.3 mg.
Table 1: Baseline characteristics (n=57)

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[Table 2] shows the difference between kidney length as measured by ultrasound and that measured by CT. The right side kidney measurement showed greater discrepancy than the left-sided measurement, the mean difference being 0.38 cm on the right side. [Table 3] shows the common renal system abnormalities with cysts being the most common finding (22.8%), followed by renal calculi and microliths (3.5% each). Collecting system abnormalities were seen in only 3.6% of all patients overall with the only abnormalities being a duplex system and calculi. The most common extrarenal anomaly was ovarian mass or cyst (seen in 8.7%), followed by fibroid uterus and cholelithiasis (3.5% each).
Table 2: Computed tomography versus ultrasound characteristics with regard to renal length estimation

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Table 3: Renal, collecting system, and extrarenal anomalies on computed tomography angiography of renal donors (n=57)

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[Table 4] shows the characteristics of the renal vasculature. Most patients had a single renal artery (87.7%) and single renal vein (80.7%). However, 10.5% of people had supernumerary renal arteries and 17.5% of individuals had supernumerary renal veins. The mean diameter of the renal artery on the right side was 5.09 mm and on the left side was 5.14 mm. Most patients had no accessory vessels. Among those with accessory vessels, two vessels were most common. Most renal veins did not have tributaries (73.7%). Among those with tributaries, three numbers of tributaries were most common. The most common tributaries were the gonadal veins and the adrenal veins [Figure 1].
Table 4: Renal vasculature morphometric analysis

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Figure 1: Tributaries of the renal vein in this patient Donor cohort (n = 57)

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The left kidney was harvested in 96.4% of donors. The median time to the elevation of creatinine postdonation was 1 day. The median time to achieve nadir creatinine postdonation was 5 days and the change of creatinine from baseline to highest value was 0.4 mg/dl, whereas the change of creatinine from baseline to new nadir was 0.25 mg/dl. The median duration of follow-up was 13.5 days.

CT findings correlated well with the intraoperative findings in 72.7% of patients. The most common abnormality noted during surgery was supernumerary arteries and veins.


  Discussion Top


Characteristics of Indian kidney donors in terms of renal angiography are a scarcely studied aspect of kidney donation. The diameter, course, accessory vessels, and tributaries need to be well described before transplant to help the surgeon during transplant surgery and for overall good outcomes. The discrepancy between expected vasculature and unexpected findings intraoperatively needs to be minimized with adequate pretransplant workup so that appropriate donors can be selected and side of donation can be chosen. This observational study looks into the baseline GFR and other nonrenal characteristics of the kidney donor with an emphasis on the attributes of the renal vessels.

The median age of donors was 46 years [Figure 1]. This is similar to other Indian studies where the mean age of donation was 41.26 years.[1] Yet another Indian study quoted the median age of the donor to be 40 years (range 18–52).[2] In this study, majority of donors were female (61.4%). This is an expected finding as there has been a strong gender disparity among living donors in the past also.[3] Comorbidities that were seen with renal donation in this study were hypothyroidism, impaired glucose tolerance, and fibroid uterus. There were no hypertensive donors in this cohort. Baseline creatinine was 0.68 mg/dl and mean GFR on DTPA was 91.2 ml/min. The right kidney had better GFR in most patients. In a study by Schold et al., depression, obesity, hypertension, hypothyroidism, and chronic obstructive pulmonary disease were the common comorbidities.[4] In comparison, data from Glasgow showed that the mean creatinine predonation was 90.2 μmol/l (1.017 mg/dl)[5] and another cohort of patients from Australia had a mean predonation mGFR of 94 ml/min/1.73 m2.[6]

The size of the kidney on the ultrasound was 0.38 cm larger than the size estimated by the CT; the difference was significant on the right side, but not for the left side [Table 2]. This is in contrast to data from other studies which state that ultrasound measurement underestimates renal length by 1.5 mm on average.[7] Interobserver variations in ultrasound assessment of kidney size can explain the discrepancy. In a study comparing renal size on ultrasound and CT with actual measures of the kidney at the time of transplant, the difference between actual measures of kidney length by ultrasound was 0.7 cm and by transverse CT was −0.8 cm.[8]

Renal abnormalities were detected in 33.3% of patients screened [Table 3]. The most common abnormalities were cysts (most common–22.8%), followed by asymptomatic renal calculi and microliths (7.0% of the study population). Collecting system abnormalities were fewer with only two patients having abnormalities. Other incidental findings on CT were those of ovarian mass or cyst (most common 9%), followed by fibroid uterus and cholelithiasis. The overall incidence of extrarenal findings was 30%. In a western study where 1957 donors were screened, the most common abnormality was kidney stones – 11% and focal scarring (3.6%).[9] In another study by Mutneja et al. involving 632 living donors, incidental extrarenal findings were noted in 525 of 632 potential donors. These findings led to an additional cost of 407$ and an added source of apprehension for the donor.[10] A cost–benefit analysis of the study population should be an area for future studies in this field.

Renal vasculature was evaluated with CT angiogram in all patients planning donation. The median number of renal arteries was 2.1 (i.e., single renal vessels for each kidney). Accessory vessels or supernumerary vessels were noted in 20.4% of patients [Table 4]. Data from Turkey showed 29.6% of donors had abnormal number of vessels.[11] Early branching of the renal artery was seen in only one donor in this cohort. In other studies, early branching had been seen in up to 12% of donors.[12] Data from Pakistan showed that the mean length of the right renal artery was 44.69 mm and the left renal artery was 35 mm. This had a significant variation with age and gender.[13] The mean length of the renal artery on the right side in this study was 31.76 mm and on the left side was 28.85 mm. This presents a much smaller length than expected. In the same study from Pakistan, the diameter of the renal artery was found to be 6.66 and 6.79 mm for the right and left sides, respectively. This was also larger than that of this current Indian cohort where the renal artery diameters were 5.14 mm and 5.09 mm, respectively. Renal artery diameter <3 mm is not compatible with transplant and was not seen in any of the study cohort.

Data on renal veins previously published from India explained that variations in renal vein anatomy were common with retroaortic veins, circumaortic veins, and plexiform left renal veins being seen in 2.5%, 4%, and 0.5% of cases, respectively.[14] In this study, the most common renal vein anomaly noted was that of a preaortic vein (26.3%), followed by a circumaortic vein seen in 5.26% of cases. The renal vein length in studies from Chennai showed a mean length of 30.1 mm on the right side and a mean length of 70.1 on the left side.[15] The length of the renal vein on the right side in this study was 19 mm and on the left side was 50.6 mm, which was smaller than the expected length by a large margin. However, it satisfied the known dictum quoted by Williams that the left renal vein is 3 times (in this case 3.8 times) the length of the right renal vein.[16] The left renal vein is generally always associated with more variation than the right side with gonadal, suprarenal, and renolumbar veins being the most common tributaries (two tributaries being seen in 34.7%) of cases.[17] In this study, most patients did not have any tributaries. Among those who had renal vein tributaries, three tributaries were more common than two. The most common ones identified were the gonadal vein and the adrenal vessels [Figure 1].

The clinical significance of the data presented above lies in that abnormality of renal vasculature makes a significant impact on the risk of complications associated with transplant surgery. For example, multiple renal vessels have been considered a relative contraindication to transplant surgery, although they have been used successfully in several transplants.[18] Size discrepancy between donor and recipient renal arteries has been noted as one of the contributing factors for the later development of transplant renal artery stenosis.[19] The shorter length of the right renal vein is what predisposes this vein for an increased risk of thrombosis in the peritransplant period.[20] Hence, size does matter to transplant outcomes and surgical complications.

At the penultimate stage of transplant evaluation, two patients had the renal transplant cancelled owing to abnormal CT findings. One cause of exclusion based on CT was extrarenal (a large ovarian mass) and another was a large cyst. In other studies, abnormalities of the collecting system accounted for the most frequent cause of exclusion (41 of 81 patients) and complex renal anatomy following close behind in 29 of 81 patients.[21] In most patients, the left side was preferred over the right for renal transplantation (96.4% vs. 3.6%). The left side has traditionally been preferred since the renal vein is longer on the left side and makes for easier anastomosis. The right side, however, has the advantage of having fewer tributaries. The discrepancy between CT and surgical findings was seen in four patients and all four instances, the discrepancies were related to abnormal renal vasculature. A study by Pozniak et al. showed a good correlation between CT angiography and surgical findings with both sensitivity and specificity of 99.6% for detecting main renal arteries. When it comes to polar vessels, sensitivity decreases to 76.9%. With renal veins, anatomy is more variable with sensitivity of 98.7% and specificity of 95.5%.[22]

The median time to reach maximum creatinine postdonation was 1 day in this study. Nadir creatinine was reached at day 5 postdonation in most patients. In this study, follow-up was limited to a median of 13.5 days, but wide variability in the follow-up time was noted varying between 3 and 1100 days. The expected postdonation GFR drop is estimated to be up to 35 ml/min/1.73 m2.[23] In this study, the follow-up period was inadequate to comment appropriately on change in GFR over time.

The strengths of the study were that an in-depth morphometric analysis of the renal vasculature and postdonation outcomes were analyzed for this donor cohort. This study has also brought out different findings when compared to other studies done in this region.

Limitations of the study

The limitations of this study are that it is from a single center and the sample size is small. Intraoperative findings of deceased donors were not analyzed as part of this study. These data represent a small cohort of patients in South India and may not be representative of statistics from the rest of the subcontinent. Detailed morphometric analysis of renal vasculature for the rest of the Indian population is an area where information is deficient.


  Conclusion Top


The gender bias of society is reflected in this transplant scenario with women being more often the source of the donor kidneys. The length and diameter of both the renal artery and renal vein appear to be smaller than previously known data. The course of the renal vessels in this cohort was also different from those in previously recorded. CT findings correlate with intraoperative findings in most cases.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Sahay M, Narayen G, Anuradha. Risk of live kidney donation – Indian perspective. J Assoc Physicians India 2007;55:267-70.  Back to cited text no. 1
    
2.
Srivastava A, Prabhakaran S, Sureka SK, Kapoor R, Kumar A, Sharma RK, et al. The challenges and outcomes of living donor kidney transplantation in pediatric and adolescent age group in a developing country: A critical analysis from a single center of north India. Indian J Urol 2015;31:33-7.  Back to cited text no. 2
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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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