Omental infarction [and epiploic appendagitis] can be summarized with the term “intraabdominal focal fat infarction”. US and CT features allow a reliable diagnosis. Both conditions occur more frequently than generally assumed and sometimes discrimination of omental infarction and epiploic appendagitis is not possible with certainity. Both omental infarction and epiploic appendagitis are self-limiting conditions, and correct diagnosis avoids unnecessary laparotomy.
Segmental Omental infarction results from either venous thrombosis or torsion of a portion of the omentum usually located in the right upper or lower quadrant. US shows a hyperechoic noncompressible intraabdominal mass which usually adheres to the parietal peritoneum (Fig. 8). In contrast to epiploic appendagitis however, the mass is larger and central hypoechoic areas are more common.
Epiploic appendagitis is one differential diagnosis of diverticulitis. Infarction of an epiploic appendage is located generally in one of the lower quadrants, more frequently on the left than on the right side. At the point of maximum tenderness US shows a moderately hyperechoic, ovoid, and noncompressible mass directly under the abdominal wall which frequently adheres to the parietal peritoneum. The mass may be surrounded by a hypoechoic rim and bowel-wall thickening is usually absent. On Colour Doppler US or contrast-enhanced US the central necrotic appendage is avascular whereas the surrounding fatty tissue shows moderate hypervarcularity.