Congenital anomalies of the inferior vena cava and left renal vein: evaluation with spiral CT.

PURPOSE: To determine with spiral computed tomography (CT) the incidence and caval location of left renal vein (LRV) variants that may affect inferior vena cava (IVC) filter placement, spermatic vein embolization, and adrenal or renal venous sampling. MATERIALS AND METHODS: Contrast material-enhanced spiral CT scans of 1,014 patients were evaluated for the incidence and configuration of LRV variants and for the distribution of the entrances of these veins into the IVC. RESULTS: In this series, variants detected were as follows: one azygos continuation of the IVC (0.1%), three bilateral IVCs (0.3%), and 102 LRV variants (10%) including 38 retroaortic renal veins (3.7%) and 64 circumaortic venous rings (6.3%). In the retroaortic renal vein group, the distance between the entrance of the LRV into the IVC and the confluence of the iliac veins was +62.5 mm +/- 8.7. In the circumaortic venous ring group, the distance between the entrances of the retroaortic and preaortic limbs into the IVC was -39.0 mm +/- 17.4; the distance between the entrance of the left retroaortic limb into the IVC and the confluence of the iliac veins was +63.2 mm +/- 17.1. CONCLUSIONS: Detailed knowledge of these anomalies is crucial for IVC filter placement, spermatic vein embolization, and adrenal or renal venous sampling