Contribution of mesenteric fat to unsatisfactory abdominal and pelvic ultrasonography.

Technically unsatisfactory abdominal and pelvic ultrasound examinations may be due to excessive mesenteric fat rather than to the presence of intestinal gas. Ultrasonography and computed tomography (CT) were performed in 34 patients. CT and ultrasound scans were obtained in the same transverse planes, and in five patients multiple ultrasound transducer frequencies were used. Mesenteric fat in the abdomen and pelvis appears on ultrasound scans as a diffuse accumulation of echoes, with poor definition of posterior structures. Ultrasonic beam scattering and defocusing are responsible for the attenuation and echogenicity. When the pattern of abundant fat is recognized with ultrasound, alternative imaging procedures should be performed to visualize the deep abdominal, retroperitoneal, and pelvic structures.