Retroaortic left renal vein

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Overview

 * Seen in 2-3% of individuals (less common than circumaortic left renal vein, seen in 5-7%)
 * Retroaortic left renal vein derived from the renal collar (circumaortic renal venous ring) at an embryonic stage and completed by the regression and disappearance of the ventral (preaortic) limb and the persistence of the dorsal (postaortic) limb at a later stage
 * Drainage of lumbar veins may also be anomalous in these cases, although by variable anatomy
 * In some cases, the retroaortic left renal vein exits the renal hilum posterior to the left renal artery (anomalous)
 * The retroaortic vein may receive flow from lumbar veins and may run caudad and enter the inferior vena cava in the lower lumbar region, or it may subdivide before entering the inferior vena cava.

Multi Sliced CT
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Additional Reading

 * Moss and Adams' Heart Disease in Infants, Children, and Adolescents Hugh D. Allen, Arthur J. Moss, David J. Driscoll, Forrest H. Adams, Timothy F. Feltes, Robert E. Shaddy, 2007 ISBN 0781786843