Anatomical study of the renal veins observed during 342 living-donor nephrectomies.

The anatomical variations of renal veins observed during 342 nephrectomies in living donors are described, 311 cases on the left side and 31 on the right. The following anatomy of the renocava veins was observed: 1. On the left side the renal vein was always unique (311/311) and had two tributaries (suprarenal and gonadal veins) in 100 per cent and one or more renolumbar veins in 65.27 per cent, encircling the aorta in 1.07 per cent, was retroaortic in 1.4 per cent; and the inferior vena cava was double in 0.64 per cent; B- on the right side the renal vein was double in 29 per cent (9/31) and had only one tributary (gonadal vein) in one case, for 3.22 per cent (1/31); three or more renal veins in 9.7 per cent (3/31). We concluded that the left renal vein is always unique, presenting variations principally in its tributaries and trajectory. On the right side, the renal vein was double or triple in 38.79 per cent.


INTROOUCTION I
t is crucial to know the anatomy of the renal vessels during a retroperitoneal approach to prevent bleeding by accidental tearing.I Comparably, the renal venous pattem of the right side bears little resemblance to that of the left.In its relatively short course from the kidney to the inferior vena cava, the right vein rarely receives a tributary.The longer left renal vein (LRV), on the contrary, regularly receives the following tributaries: suprarenal and inferior phrenic, from above, frequently joined; gonadal (testicular or ovarian) from below; and renolumbar vein posteriorly, often by a confluent with the gonadal vein.During the living donor nephrectomy, the left kidney is used more often as a donor organ because its vein is longer than the right renal vein.Usually, the LRV anteriorly crosses the aorta before reaching the vena cava. 4Our objective was to show the anatomical variations of the renal veins observed in 342 living donor nephrectomies.

Right side
In 31 cases' submitted to a right nephrectomy, we found that: A.
19 (61.29 per cent) cases had only one renal vein; B. 9 (29 per cent) had two renal veins (one case had a gonadal tributary), and that; C.

DISCUSSION
We found that the left renal vein always had two tributaries, the suprarenal vein superiorly and a gonadal vein (testicular or ovarian veins) inferiorly in 100 per cent, and usually one or more renolumbar veins in 65.27 per cento Lejars 6 found one or more renolumbar veins of LRV in 88 per cent, Yang et a1.cephalad direction for better mobilization of the left renal vein.By increasing the mobility of the left vein and the inferior cava, this maneuver provides excellent exposure of the both renal arteries and precludes the necessity of transecting the left renal vein.We observed that the renolumbar vein vessels on the left side may be single or multiple, and that they had many variations in their width and local that reach the left renal vein.Usually, they reached the LRV close to the gonadal vein, as was found by Anson & Kurth, 9 Anson & Daseler,4 and Pinto. 8n our research, on the left side we observed the LRV was always unique, retroaortic in 1.28 per cent, circumaortic venous ring in 0.96 per cent; and a duplication of the inferior vena cava in 0.64 per cento Lattore lO observed that the LRV is retroaortic in 1-3.4 per cent, circumaortic in 6-8.7 per cent and that the inferior vena cava is double from 1-3 per cento Pint0 8 found that the LRV is retroaortic in 1.98 per cent, circumaortic in 1.98 per cent, and the inferior vena cava double in 0.99 per cento On the right side, we found a double renal vein in 29 per cent, and triple or more in 9.7 per cent of the 31 nephretomies, but Anson et aI. 2 said that the right vein is occasionally double and rarely tripled, and is uncommonly the recipient of tributaries.Pint0 8 found a double right renal vein in 22.77 per cento We observed that when the angiography showed more than one renal artery, it was more common to find two or more renal veins on the right~side during surgery.3,5It is clear that when the left renal vein curves inferior in preoperative angiography, it strongly suggests that it courses retroaortic.3 ,7 This confirms the importance of a complete preoperative angiography (arterio-and venographific phases) to decide which kidney should be removed.3 ,5 When either kidney is demonstrated to be satisfactory, the left is usually chosen because the longer renal vein contributes to the technical ease of the nephrectomy and subsequent transplante These anatomical variations of the renocava veins must be kept in mind to prevent bleeding by an accidental lesion when operating in the retroperitoneal region.

CONCLUSION
We concluded that the renal veins were: 1.

FIGURE 2 -
FIGURE 2 -Nephrectomy on right side showing the veins encountered: a-one renal vein, b-two rena' veins, c-three renal veins.

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in 60.8 per cent, Cooley & Wukasch l in 95 per cent and Pint0 8 in 63.36 per cent of the cases.On the right side, we found just one tributary only once, the gonadal in 3.22 per cent, while Anson & Kurth,9 Anson & Daseler4 found it in 10-20 per cent, and Pint0 8 in 10.89 per cent.Cooley & Wukasch l have said that in aortic abdominal disease, trauma of the renal vessels of the left side, it is very important to do the ligation and section of the renolumbar, testicular and suprarenal veins in a , J.C.C.; VERíSSIMO, M.J.; CASTRO, M.J.; CÂMARA, A.L.G.; PESTANA, J.O.M. -Anatomical study of the renal veins observed during 342 living-donor nephrectomies São Paulo Medicai Journal/RPM 115(3): 1456-1459,1997

Table 1
Results of 342 living-donor nephretomies showing the variations of the renal veins and their tributaries.