Communicating vein between the left renal vein and left ascending lumber vein: incidence and significance on abdominal CT.

PURPOSE To examine the incidence and appearance of the communicating vein between the left renal vein (LRV) and the left ascending lumbar vein (LALV) on abdominal CT. MATERIALS AND METHODS We reviewed the appearance of the communicating vein on contrast-enhanced CT obtained by multidetector-row CT (MDCT) scanner. One hundred patients without known abnormality in this region were randomly chosen and the following findings were recorded: (1) presence or absence of the visible communicating vein, (2) diameter of the communicating vein, (3) visible length of the vein (none, partial, or total), (4) laterality of the ascending lumbar vein, (5) distance between the superior mesenteric artery and the aorta. RESULTS The communicating vein was visible in 35 patients (35%). In 20 cases, this vein was visualized within the paraaortic region and could not be traced toward the LALV. The distance between the superior mesenteric artery and the aorta was narrower in the patients with visible communicating vein than in those without it, however, no statistically significant difference was demonstrated. CONCLUSION This vein is commonly visible in the general population, and care should be taken not to confuse it with lymphadenopathy because this communicating vein was partially visualized within the paraaortic region in 20% of the cases.