Surg Radiol Anat DOI 10.1007/s00276-014-1403-6

ORIGINAL ARTICLE

Classification of the renal vein variations: a study with multidetector computed tomography Jingqi Zhu • Lei Zhang • Zhangwei Yang Huang Zhou • Guangyu Tang

•

Received: 23 August 2014 / Accepted: 8 December 2014 Ó Springer-Verlag France 2015

Abstract Purpose To estimate the incidence, anatomical feature as well as type of the renal vein variation with multidetector computed tomography (MDCT) in an adult population. Methods A total of 1,452 patients who underwent MDCT angiography were retrospectively evaluated for the presence (number, length, origination, destination, branching pattern and course) of the renal vein variation. v2 test was used to compare the incidence of variations in left and right renal veins and the incidence of variations in each side renal vein between males and females. Results Renal vein variations were observed in 358 patients (24.7 %, 358/1,452), which included 103 patients (7.1 %, 103/1,452) with left renal vein (LRV) variations, 279 patients (19.2 %, 279/1,452) with right renal vein (RRV) variations and 24 patients (1.7 %, 24/1,452) with bilateral renal vein variations. The frequency of RRV variations was significantly higher than that of LRV variations (p \ 0.05). No statistically significant correlation was found between variations of renal vein (LRV and RRV) and gender (p [ 0.05). According to the morphology of the renal vein, we classified LRV variations into five types: type I, circumaortic LRV (2.1 %, 31/1,452); type II, retroaortic LRV (2.1 %, 30/1,452); type III, abnormal reflux (1.7 %, 24/1,452); type IV, late venous confluence of J. Zhu
G. Tang (&) Department of Radiology, Shanghai Tenth People’s Hospital, Tongji University School of Medicine, 301 Middle Yanchang Road, Shanghai 200072, China e-mail: [email protected] J. Zhu
L. Zhang
Z. Yang
H. Zhou Department of Radiology, East Hospital, Tongji University School of Medicine, Shanghai 200120, China

LRV (0.9 %, 13/1,452); type V, rare type (0.3 %, 5/1,452), and RRV variations into three types: type 1, additional renal vein (18.7 %, 271/1,452); type 2, abnormal reflux (0.4 %, 6/1,452); type 3, rare type (0.1 %, 2/1,452). Conclusion The renal vein variations are not unusual, particularly in the RRV. Anomalies of the LRV are more complex than those of the RRV. The renal vein anatomy can be well depicted by MDCT angiography. Our new classification of the renal vein variations will improve the recognition of the renal vein morphology preoperatively. Keywords Variation
Renal vein
X-ray computed tomography

Introduction Kidneys are drained by left and right renal veins. The left renal vein (LRV) passes the space between the superior mesenteric artery and the abdominal aorta, then it opens into the inferior vena cava (IVC). However, the right renal vein (RRV) directly opens into the IVC with a shorter course. The LRV is approximately three times longer than the RRV. Variations of renal vein are frequent and result from anomalies in vessel embryogenesis. Knowledge on the renal vein variations is very important for retroperitoneal operation, interventional procedure, diagnosis of nutcracker syndrome and staging for renal cancers, particularly in renal transplantation [4, 12, 14, 16, 17]. Variations of renal vein are usually silent and unnoticed until they are found by the retroperitoneal surgery, radiologic examination or necropsy. Multidetector computed tomography (MDCT) is a preferable imaging modality in the evaluation of renal vein variations since it has improved spatial and

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temporal resolution and better z-axis resolution. Many studies have reported that MDCT can provide an accurate evaluation of the renal vein anatomy in living renal donors. The sensitivity, specificity and accuracy for identifying the number of renal veins on MDCT angiography are 94.44–98, 94.11–96.07 and 94.3–99 %, respectively [3, 9, 11, 18]. But few studies introduced a comprehensive classification system for the renal vein variations. In our study, based on the high-quality MDCT angiography, we classified the renal vein variations in detail.

Materials and methods Subjects 1,452 patients who underwent abdominal MDCT angiography from September 2006 to May 2014 at the East Hospital affiliated to Tongji University School of Medicine (Shanghai, China) were recruited for the study. This group consisted of 767 men and 685 women with an age range of 19–94 years (mean age ± standard deviation, 56 ± 15 years). Exclusion criteria included less than 18 years old, situs inversus viscerum, severe artifacts impairing accurate evaluation, congenital diseases of the kidneys and renal tumors. Institutional review board permission was obtained for the retrospective review of medical records and MDCT images without informed consent. CT scanner and technique MDCT examinations were performed with a 64-detector CT scanner (n = 620, Philips Brilliance, Philips Medical Systems, Eindhoven, The Netherlands) or a dual-source CT scanner (n = 832; Somatom Definition Flash, Siemens Healthcare, Forchheim, Germany). The venous images from MDCT angiography were acquired in the arterial and venous phases after the contrast agent (Ultravist, 370 mgI/ ml, Bayer Schering, Berlin, Germany; 1.2 ml/kg body weight) was injected at a flow rate of 3.5–4 ml/s followed by 30 ml of saline solution. Contrast agent application was controlled by bolus tracking in the abdominal aorta (threshold 120 Hounsfield units) cranial to the kidneys. Arterial-phase acquisition was initiated with a mean delay of 6 s after reaching the threshold. Venous-phase acquisition began 85 s after the start of injection of the intravenous contrast agent. The coverage of MDCT scan extended from the diaphragmatic dome to iliac crest level. CT parameters were as follows: tube voltage 120 kV, tube current 250 mA/s, detector collimation 64 9 0.6 or 64 9 0.625 mm, gantry rotation time 750 ms, pitch 1.0–1.2, field of view 350 mm and matrix 512 9 512. Axial slices with a slice thickness of 0.75–0.9 mm and a

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slice increment of 0.40–0.45 mm were reconstructed. The multiplanar reformation (MPR), maximum intensity projection (MIP) and volume rendering (VR) in arterial and venous phases were used for image post-processing and image analysis. Image analysis MDCT angiographic images were independently analyzed on workstations by two radiologists with 20 and 30 years of experience in abdominal radiology, respectively. Based on the characteristics of renal veins (including number, length, origination, destination, branching pattern and course), a classification system for renal vein variations was proposed with unique descriptive names given for each type. To describe the course of LRV briefly, course 1 is defined as LRV running anteriorly to the abdominal aorta and draining into the IVC; course 2 is defined as LRV running posteriorly to the abdominal aorta and draining into the IVC; and course 3 is defined as LRV following a course downward for a distance and then crossing behind the left common iliac artery and draining into the left common iliac vein. Statistical analysis Continuous data were expressed as mean ± standard deviation. Categorical data were presented in frequencies and percentages. v2 test was used to compare the incidence of variations in left and right renal veins and the incidence of variations in each side renal vein between males and females. Statistical analyses were performed using SPSS 13.0 (SPSS Inc., Chicago, IL, USA). A two-sided p value of less than 0.05 was considered to indicate statistical significance.

Results Renal vein variations were observed in 358 patients (24.7 %, 358/1,452; 192 males and 166 females), which included 103 patients (7.1 %, 103/1,452; 58 males and 45 females) with LRV variations, 279 patients (19.2 %, 279/1,452; 149 males and 130 females) with RRV variations and 24 patients (1.7 %, 24/1,452; 15 males and 9 females) with bilateral renal vein variations. The frequency of RRV variations was significantly higher than that of LRV variations (p \ 0.05). No statistically significant correlation was found between variations of renal vein (LRV and RRV) and gender (p [ 0.05). Among these anomalies, LRV variations could be classified into five types (type I–V; Table 1) and RRV variations could be classified into three types (type 1–3; Table 1). The detailed characteristics of each type could be

Surg Radiol Anat Table 1 Classification of renal vein variations in 1,452 patients Classification

Morphology

LRV variations Type I (circumaortic LRV)

(A)

(A)

(B)

(A)

(B)

(A)

(A)

(A)

(B)

(B)

(B)

(B)

Type II (retroaortic LRV)

Type III (abnormal reflux)

Type IV (late venous confluence of LRV)

Type V

Figs. 5-7

(rare type) RRV variations Type 1 (additional renal vein)

Type 2 (abnormal reflux)

(A) Type 3

(B) Fig. 9

Figs. 10 and 11

(rare type)

LRV left renal vein, RRV right renal vein, A subtype A, B subtype B, filled upper triangle inferior vena cava, filled heart abdominal aorta, filled square left common iliac vein, filled lower triangle left lumbar vein, filled circle vena hemiazygos

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Surg Radiol Anat Table 2 Proportion of the renal vein variations in 1,452 patients Classification LRV variations

Proportion 7.1 % (103/1,452)

Type I

2.1 % (31/1,452)

IA

0.7 % (10/1,452)

IB

1.4 % (21/1,452)

Type II

2.1 % (30/1,452)

IIA

1.7 % (25/1,452)

IIB

0.3 % (5/1,452)

Type III

1.7 % (24/1,452)

IIIA

0.5 % (7/1,452)

IIIB

1.2 % (17/1,452)

Type IV Type V

0.9 % (13/1,452) 0.3 % (5/1,452)

RRV variations

19.2 % (279/1,452)

Type 1

18.7 % (271/1,452)

Type 2

0.4 % (6/1,452)

2A

0.3 % (5/1,452)

2B

0.1 % (1/1,452)

Type 3

0.1 % (2/1,452)

Bilateral renal vein variations

1.7 % (24/1,452)

LRV left renal vein, RRV right renal vein

Fig. 1 A 54-year-old man with a variation of type IA (circumaortic LRV). VR image shows that single LRV is divided into two branches, one of them (arrow) runs anteriorly to the abdominal aorta and drains into the IVC while the retroaortic limb is divided into two branches (arrowheads) coursing behind the abdominal aorta to drain into the IVC separately

depicted in MDCT angiography as follows. Descriptive and percentage information about the renal vein variations was summarized in Table 2.

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Fig. 2 A 20-year-old man with a variation of type IB (circumaortic LRV). VR image shows two LRVs arising separately from the hilum, one of them (short arrow) runs anteriorly to the abdominal aorta and drains into the IVC (black arrow) while the retroaortic limb (long arrow) is divided into two branches (arrowheads) coursing behind the abdominal aorta to drain into the IVC separately

Type I (circumaortic LRV, CLRV): this type took up 30.1 % (31/103) of patients with LRV variations. It was divided into two subtypes. IA: single LRV divided into two branches which followed course 1 and course 2, respectively (n = 8), or one of them followed course 1 while the other followed course 3 (n = 2). Of the ten patients, 1 was special who showed that the retroaortic limb was divided into two branches following course 2 separately (Fig. 1). IB: two LRVs arised separately from the hilum. One of them followed course 1 while the other followed course 2 (n = 20), or one of them followed course 1 while the other followed course 3 (n = 1). Of the 21 patients, 2 were special who showed that the retroaortic limb was divided into two branches following course 2 separately (Fig. 2). Type II (retroaortic LRV, RLRV): this type took up 29.1 % (30/103) of patients with LRV variations. It was divided into two subtypes. IIA: single LRV followed course 2 (n = 25). Of the 25 patients, 1 was special who showed that the LRV was divided into two branches following course 2 separately (Fig. 3). IIB: single LRV followed course 3 (n = 5). Type III (abnormal reflux): this type took up 23.3 % (24/ 103) of patients with LRV variations. It was divided into two subtypes. IIIA: single LRV arising from the renal

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Fig. 3 A 78-year-old woman with a variation of type IIA (retroaortic LRV). VR image shows that the LRV (long arrow) is divided into two branches (arrowheads) coursing behind the abdominal aorta to drain into the IVC (short arrows) separately

hilum followed course 1, while an abnormal vein originating from the upper or lower pole of the kidney followed course 2 (n = 4), course 3 (n = 2) or drained into the left lumbar vein (n = 1). IIIB: single or multiple LRV(s) drained into the adjacent vein including the left limb of double IVC (n = 11; 0.8 %, 11/1,452), left-sided

Fig. 4 A 58-year-old man with a variation of type IIIB (abnormal reflux). MPR image shows that single LRV (long arrow) drains into vena hemiazygos (short arrow) instead of the IVC (arrowheads)

IVC (n = 5; 0.3 %, 5/1,452) or vena hemiazygos (n = 1; Fig. 4). Type IV (late venous confluence of LRV): this type took up 12.6 % (13/103) of patients with LRV variations. It was defined as a final confluence point within 1.5 cm from the left lateral border of the abdominal aorta for the LRV. Type V (rare type): this type took up 4.9 % (5/103) of patients with LRV variations. Two patients both showed variations of type IA, which formed a venous circle around the abdominal aorta before draining into the IVC. One of them also showed a vein arising from the renal hilum followed course 2 (Fig. 5), while the other one showed a vein originating from the lower pole of the kidney followed course 2. One patient showed a variation of type IV, and an abnormal vein originating from the posterior tributary near the renal hilum followed course 2 (Fig. 6). One patient showed a variation of type IB with a limb following course 3, and a branch originating from the lower pole of the kidney followed course 2. Another patient showed a LRV followed course 1, and an abnormal vein originating from the superior tributary near the renal hilum followed course 3 (Fig. 7). Type 1 (additional renal vein): this type took up 97.1 % (271/279) of patients with RRV variations. It was defined as multiple RRVs arising from the renal hilum and draining into the IVC. In this type, the number of RRVs was 2

Fig. 5 A 62-year-old man with a variation of type V (rare type). VR image shows a variation of type IA, which forms a venous circle (arrowheads) around the abdominal aorta before draining into the IVC, and also shows that a vein (arrow) arising from the left renal hilum follows a course downward for a distance and then crosses behind the abdominal aorta and drains into the IVC

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Fig. 8 An 86-year-old man with a variation of type 1 (additional renal vein). MIP image shows two RRVS. Superior RRV (black arrowhead) is divided into two branches (white arrowheads) draining into the IVC separately, and the inferior RRV (arrow) drains into the IVC directly Fig. 6 An 87-year-old man with a variation of Type V (rare type). MIP image shows a variation of type IV (arrowhead), and an abnormal vein (arrow) originating from the posterior tributary near the renal hilum crosses behind the abdominal aorta and drains into the IVC

Fig. 9 A 41-year-old man with a variation of type 2B (abnormal reflux). MIP image shows single RRV (arrowheads) goes through the renal parenchyma and drains into the right lumbar vein

Fig. 7 A 28-year-old man with a variation of type V (rare type). MIP image shows that a normal LRV (arrowhead) drains into the IVC, and an abnormal vein (arrows) originating from the superior tributary near the renal hilum follows a course downward for a distance and then crosses behind the left common iliac artery and drains into the left common iliac vein

(n = 210), 3 (n = 52) and 4 (n = 9), respectively. Of the 271 patients, one was special who showed two RRVS. Superior RRV was divided into two branches draining into the IVC separately, and the inferior RRV drained into the IVC directly (Fig. 8). Type 2 (abnormal reflux): this type took up 2.2 % (6/279) of patients with RRV variations. It was divided into two subtypes. 2A: single RRV arising from the renal hilum drained into IVC, while the abnormal vein originating from the upper or lower pole of the kidney drained into the IVC

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(n = 5). 2B: single RRV drained into the adjacent vein such as the right lumbar vein (n = 1; Fig. 9) instead of the IVC. Type 3 (rare type): this type took up 0.7 % (2/279) of patients with RRV variations. One patient showed two RRVs arising from the renal hilum drained into the IVC and a vein originating from the lower pole of the kidney drained into the IVC (Fig. 10). The other patient showed two RRVs. The superior RRV drained into the IVC and the inferior RRV drained into the distal segment of LRV (Fig. 11).

Discussion The embryogenesis of the bilateral renal veins is closely related with the development of the IVC. The renal veins

Surg Radiol Anat

Fig. 10 A 73-year-old woman with a variation of type 3 (rare type). MIP image shows two RRVs (arrowheads), and a vein (arrow) originating from the lower pole of the kidney drains into the IVC

Fig. 11 A 75-year-old man with a variation of type 3 (rare type). VR image shows two RRVs. The superior RRV (arrowhead) drains into the IVC and the inferior RRV (short arrow) drains into the distal segment of LRV (long arrow)

and IVC occur between the fourth and the eighth gestational weeks by the sequent formation, anastomoses and regression of three paired veins (posterior cardinal, subcardinal and supracardinal veins) [19, 22]. The subcardinal veins and the supracardinal veins form a circumaortic venous ring, which consists of subcardinal veins and intersubcardinal anastomosis anteriorly, supracardinal veins and intersupracardinal anastomosis posteriorly, and

supracardinal–subcardinal anastomosis on each side [13]. The symmetrical cardinal venous system drains into the right-sided IVC at around 8 weeks [21]. Anomalies during the development process cause the variations of renal vein and IVC. The most common anomalies of the LRV are CLRV and RLRV [1, 5, 9, 10]. CLRV results from persistence of the dorsal arch of the renal ring and intersupracardinal anastomosis. Persistence of the intersupracardinal anastomosis and regression of the intersubcardinal anastomosis and ventral arch result in the formation of RLRV. Previous studies reported the prevalence of CLRV and RLRV as 0.3–6.3 and 0.5–3.7 %, respectively [5, 20, 23]. Our results are consistent with the prior reports. The most common variation of the RRV is additional renal vein (20–23 %) [8, 18, 20], which is also similar to our work. The most frequent variations of IVC are left-sided IVC and double IVC, which are closely related with the anomalies of the LRV [5, 7, 20]. Persistence of the left supracardinal vein results in the formation of double IVC and regression of the right supracardinal vein results in the formation of left-sided IVC. Prevalence of double IVC and left-sided IVC had been reported as 0.2–3 and 0.2–0.5 %, respectively [5, 23]. In our study, the incidence of IVC variations is concurrent with other series. According to the prior reports [5, 8, 18, 20], our results show that the incidence of renal vein variations in Chinese population is similar to that of other races. The incidence of RRV variations is more common than that of LRV variations (19.2 vs. 7.1 %). However, the types of RRV variations are less complex than those of LRV variations (3 vs. 5 types). This phenomenon depends on the different embryological development of the bilateral renal veins. Our study also shows a prevalence of bilateral renal vein variations (1.7 %) in Chinese adults which has never been reported in prior studies. Previous studies reported no statistical significance between LRV variations and gender [6, 24]. Dilli et al. [5] found that RLRV was more common in females than in males. In the present study, no significant relationship is found between renal vein variations and gender. The difference may be due to the number and constitution of patients. To our knowledge, a few studies introduced the classification of renal vein variations. Aljabri et al. [1] classified the LRV variations into five types: (1) RLRV; (2) CLRV; (3) left-sided IVC without situs inversus; (4) left-sided IVC with situs inversus; (5) duplicate IVC. Karaman et al. [10] categorized the LRV abnormalities into four types: (1) RLRV joining the IVC in the orthotopic position; (2) RLRV joining the IVC at level L4–L5; (3) CLRV; (4) RLRV joining the left common iliac vein. Natsis et al. [15] proposed a classification of CLRV into three different forms: (1) one LRV splitting into two branches, a preaortic

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and a retroaortic, draining into the IVC; (2) two LRVs, the one preaortic and the other retroaortic, draining into the IVC; (3) either anastomoses between the preaortic and retroaortic vein, being multiple or not, or multiple preaortic or retroaortic renal veins without anastomoses. Variations concerning the RRV are mostly additional renal vein [2]. A few rare anomalies of RRV have been described from case report. Lavy et al. [14] discovered an unusual case of Y-shaped RRV during the routine dissection. Kim et al. [12] reported an extremely rare case of a right circumaortic renal vein combined with a right ectopic kidney by MDCT. Based on the MDCT findings of 1,452 patients and a literature review, we propose a more comprehensive classification of the renal vein variations in detail. Our classification has some features as follows: (1) number, length, origination, destination, branching pattern and course are taken into consideration as classification; (2) the renal vein variations are classified based on each side; (3) subtypes are added in some types; (4) although a few renal vein variations confirmed by other studies have not been found in our study [12, 14], they belong to some types of our classification; (5) our study also presents a few rare renal vein variations which have never been described, either anatomically by dissection or radiologically. This new classification will improve the prior systems because it contains more detailed anatomic information, which can be depicted by reliable MDCT angiography prior to management, particularly in the evaluation of venous anatomy in potential renal donors before laparoscopic nephrectomy. Some limitations exit in our study. First, all participants recruited from a single medical center are patients with various abdominal problems. Healthy population and patients without abdominal problems are not included, which may lead to selection bias. Second, we have no comparative study between digital subtraction angiography and MDCT angiography for evaluating the renal vein variations. In conclusion, the renal vein variations are not unusual, particularly in the RRV. Anomalies of the LRV are more complex than those of the RRV. The renal vein anatomy can be well depicted by MDCT angiography. Our new classification of the renal vein variations will improve the recognition of the renal vein morphology preoperatively. Conflict of interest

None.

References 1. Aljabri B, MacDonald PS, Satin R, Stein LS, Obrand DI, Steinmetz OK (2001) Incidence of major venous and renal anomalies relevant to aortoiliac surgery as demonstrated by computed tomography. Ann Vasc Surg 15(6):615–618

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2. Ballesteros LE, Saldarriaga V, Ramirez LM (2014) Morphologic evaluation of the renal veins: a study with autopsy material from Colombian subjects. Rom J Morphol Embryol 55(1):77–81 3. Chai JW, Lee W, Yin YH, Jae HJ, Chung JW, Kim HH, Park JH (2008) CT angiography for living kidney donors: accuracy, cause of misinterpretation and prevalence of variation. Korean J Radiol 9(4):333–339 ´ , Doros A, Lovro´ Z, Toronyi E, Kova´cs JB, Ve´gso¨ G, 4. Dea´k PA Piros L, To´th S, Langer RM (2011) The significance of the circumaortic left renal vein and other venous variations in laparoscopic living donor nephrectomies. Transplant Proc 43(4): 1230–1232 5. Dilli A, Ayaz UY, Kaplanog˘lu H, Saltas H, Hekimoglu B (2013) Evaluation of the left renal vein variations and inferior vena cava variations by means of helical computed tomography. Clin Imaging 37(3):530–535 6. Dilli A, Ayaz UY, Karabacak OR, Tatar IG, Hekimoglu B (2012) Study of the left renal variations by means of magnetic resonance imaging. Surg Radiol Anat 34(3):267–270 7. Eid N, Ito Y, Otsuki Y (2013) The left inferior vena cava: a surgically important variant tributary of left renal vein. Surg Radiol Anat 35(5):455–456 8. Janschek EC, Rothe AU, Ho¨lzenbein TJ, Langer F, Brugger PC, Pokorny H, Domenig CM, Rasoul-Rockenschaub S, Mu¨hlbacher F (2004) Anatomic basis of right renal vein extension for cadaveric kidney transplantation. Urology 63(4):660–664 9. Kang M, Kalra N, Sharma A, Kumar A, Minz M, Khandelwal N (2009) Single-phase 16-slice multidetector computed tomographic angiography in the evaluation of the venous system in potential laparoscopic renal donors. J Comput Assist Tomogr 33(5):710–714 10. Karaman B, Koplay M, Ozturk E, Basekim CC, Ogul H, Mutlu H, Kizilkaya E, Kantarci M (2007) Retroaortic left renal vein: multidetector computed tomography angiography findings and its clinical importance. Acta Radiol 48(3):355–360 11. Kim JK, Park SY, Kim HJ, Kim CS, Ahn HJ, Ahn TY, Cho KS (2003) Living donor kidneys: usefulness of multi-detector row CT for comprehensive evaluation. Radiology 229(3):869–876 12. Kim MK, Ku YM, Chun CW, Lee SL (2013) MDCT findings of right circumaortic renal vein with ectopic kidney. Korean J Radiol 14(5):786–788 13. Kyung DS, Lee JH, Shin DY, Kim DK, Choi IJ (2012) The double retro-aortic left renal vein. Anat Cell Biol 45(4):282–284 14. Lavy M, Martin L, Eouzan D, Turco C, Heyd B, Mantion G, Parratte B, Tatu L (2014) An unusual case of Y-shaped right renal vein. Surg Radiol Anat. doi:10.1007/s00276-014-1280-z (Epub ahead of print) 15. Natsis K, Tsitouridis I, Totlis T, Levva S, Tsikaras P, Skandalakis P (2008) Proposal for classification of the circumaortic renal collar’s morphology. Am Surg 74(12):1190–1194 16. Ogul H, Bozkurt M, Kantarci M (2009) Images in clinical urology. Why we did not use left side for this donor. Urology 74(1):67 17. Panagar AD, Subhash RL, Suresh BS, Nagaraj DN (2014) Circumaortic left renal vein-a rare case report. J Clin Diagn Res 8(3):111–112 18. Patil UD, Ragavan A, Nadaraj, Murthy K, Shankar R, Bastani B, Ballal SH (2001) Helical CT angiography in evaluation of live kidney donors. Nephrol Dial Transplant 16(9):1900–1904 19. Salder TW (2004) Langman’s medical embryology, 9th edn. Lippincott Williams & Wilkins, Baltimore, pp 223–275 20. Satyapal KS, Kalideen JM, Haffejee AA, Singh B, Robbs JV (1999) Left renal vein variations Surg Radiol Anat 21(1):77–81 21. Suma HY, Roopa K (2011) Retro-aortic left renal vein—an anatomic variation description and review of literature. J Anat Embryol 116(3):144–147

Surg Radiol Anat 22. Tore HG, Tatar I, Celik HH, Oto A, Aldur MM, Denk CC (2005) Two cases of inferior vena cava duplication with their CT findings and a review of the literature. Folia Morphol (Warsz) 64(1):55–58 23. Trigaux JP, Vandroogenbroek S, De Wispelaere JF, Lacrosse M, Jamart J (1998) Congenital anomalies of the inferior vena cava

and left renal vein: evaluation with spiral CT. J Vasc Interv Radiol 9(2):339–345 24. Yes¸ ildag˘ A, Adanir E, Ko¨rog˘lu M, Baykal B, Oyar O, Gu¨lsoy UK (2004) Incidence of left renal vein anomalies in routine abdominal CT scans. Tani Girisim Radyol 10(2):140–143

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