The lesser omentum between the left lobe of the liver and the aorta at the level of the celiac axis harbors the left gastric vein and artery, lymphatics, nerves, and some fatty tissue. In one study, it was found to be thickened in most of 50 children with portal hypertension, but normal values were not established. Lesser omental thickness was measured in 150 children without systemic, liver, or renal disease, and it was found that it did not exceed 1.7 times the diameter of the aorta at the same level. Increased measurements were obtained in children with portal hypertension, obesity, or systemic steroid therapy (by fatty infiltration), preaortic lymphadenopathy, or with transient interposition of the gastric antrum or pancreas between the liver and aorta. In the absence of obesity or lymphadenopathy, a lesser omentum measuring more than 1.7 times the aortic diameter should raise the possibility of portal hypertension.