Abstract: Objective　To explore the multi-slice spiral CT (MSCT) manifestation and clinical significance of double inferior vena cava (IVC).　Methods　Eighteen patients with the double IVC found by multi-phase enhanced abdominal MSCT scans were collected. Three kinds of post-processing reconstruction methods including MPR, MIP and VR were used for analysis IVC variation . Their clinical and radiological data were analyzed retrospectively and the double IVC’ imaging features, embryological mechanisms and clinical significance were discussed in combination with literature.　Results　There were 3 types of MSCT manifestation in the 18 patients with the double IVC. 15 patients (accounting for 83.33%) of type I showed as that the left-sided IVC ascended vertically to the position where the left renal vein merged into, then travelled to the right in front of the aorta in a normal way of the left renal vein and merged into the normal right-sided IVC. Two patients (accounting for 11.11%) of type II showed as that the right-sided IVC ascended to the second lumbar level, then crossed the aorta posteriorly to drain into left-sided IVC, and next connected with the hemizygous vein and eventually drained into the right atrium via the azygos vein and superior vena cava. Right renal vein mainly drained into the right suprarenal IVC, but there were collateral branches connecting to the right infrarenal IVC. One patient (accounting for 5.56%) of type III showed as that the right-sided IVC travelled normally all the way, after the left IVC ascended vertically to the position where the left renal vein merged into, then it travelled right and upward behind the aorta and connected to the azygos vein.　Conclusions　Double IVC has many complex variant types, which has important clinical significance for retroperitoneal surgery and treatment of venous thrombosis of the lower body.

Key words:  , Inferior vena cava, 　Vascular malformations, 　Typing, 　Tomography/X-ray computed