Renal vein variants-Retroaortic vein

Axial and thick maximum intensity projection CT images in a 46 year old female donor scheduled for donor nephrectomy showing retroaortic left renal vein (arrows) and double renal vein on the right side (arrow head).

Discussion:

Most common is multiple renal veins, seen in approx 15-30% of individuals. 

The most common anomaly of the left renal venous system is the circumaortic renal vein, seen in up to 17% of patients 

I. There are two common variants of the circumaortic vein: 

1. The most common variant (approximately 75% of cases), one renal vein at the renal hilum subsequently divides before entering the inferior vena cava. 

2. The less common variant, two distinct veins originate from the renal hilum.

II. A less common venous anomaly is the complete retroaortic renal vein, seen in 3% of patients. Here, the single left renal vein courses posterior to the aorta and drains into the lower lumbar portion of the inferior venacava.

Alternatively, the retroaortic renal vein can drain into the iliac vein.