Portomesenteric vein gas: Pathologic mechanisms, CT findings, and prognosis

Portomesenteric vein gas is a rare condition whose pathogenesis is not full y understood. Portomesenteric vein gas is most commonly caused by mesenteri c ischemia but may have a variety of other causes. The primary factors that favor the development of this pathologic entity are intestinal wall altera tions, bowel distention, and sepsis. Portomesenteric vein gas is idiopathic in approximately 15% of cases. Advanced imaging techniques such as compute d tomography (CT) have increased the sensitivity for detection of portomese nteric vein gas. At CT, portal vein gas appears as tubular areas of decreas ed attenuation in the liver, predominantly in the left lobe. Gas in the gre at mesenteric veins can easily be demonstrated with contrast material-enhan ced CT, whereas gas in the small mesenteric veins appears as tubular or bra nched areas of decreased attenuation in the mesenteric border of the bowel. Findings of portomesenteric vein gas at CT should be carefully evaluated i n, the prognosis the context of clinical findings. In the majority of cases is favorable and surgery is not required. However, when CT demonstrates po rtomesenteric vein gas and clinical findings suggest the presence of mesent eric ischemia, surgery is mandatory.