PURPOSE: To assess the causes of periportal low attenuation, as seen on CT, in patients with blunt abdominaltrauma. MATERIALS AND METHODS: From among 812 patients who underwent abdominal CT after blunt abdominal trauma,we retrospectively analysed the findings in 124 with evidence of periportal low attenvation. Among these, hepaticinjury was noted in only 87. The presence or absence, and extent of hepatic injury, and of periportal lowattenuation, as seen on CT, were carefully evaluated. In each case, the ratio of the transverse diameter of theinferior vena cava(IVC) to the aorta at the level of the right adrenal gland provided an indirect measurement ofcentral venous pressure; for control purposes, the ratio was also obtained in 21 non-traumatic patients with noabnormal abdominal CT findings. RESULTS: Of the 87 patients with hepatic injury, 46 showed no periportal lowattenuation, and the average value of the ratio between the IVC and aorta was 1.16+/-0.12, while the remaining 41patients showed periportal low attenuation with a ratio of 1.51+/-0.21(p<0.05). In the 37 patients with periportallow attenuation but no evidence of concomitant hepatic injury, the average ratio was 1.52+/-0.25, while in 21non-traumatic patients it was 1.15+/-0.16. For resustication, all patients had received 0.5-5.0l of IV fluidtherapy before CT, and at the time of CT, were normotensive. CONCLUSION: Rapidly elevated central venous pressurefollowing massive IV infusion therapy in patients with blunt abdominal trauma can be one of the causes ofperiportal low attenuation, as seen on CT.