medially will provide a focused area of investigation for the appendiceal body A noninflammed appendix will have intact gut wall signature with intact peristalsis An acute appendicitis will have notable increase in size measuring mm or greater, be noncompressible, and will often have surrounding periappendiceal fat stranding (Fig 131.21 and Video 131.20 ) FIGURE 131.21 Appendicitis Note the enlarged appendix (arrow ) adjacent to the iliac vessels (IV) and near the psoas muscle (PM) viewed in cross section Pitfalls Obesity often prevents visualization of the appendiceal body on ultrasound In a patient with significant abdominal pain the ultrasound examination can cause pain that limits the ability to perform graded compression This can be mitigated with narcotic analgesia but in a patient with peritonitis, there may still be difficulty in obtaining adequate images Retrocecal appendiceal bodies often require a lateral approach and it may not be feasible to identify with the limited depth of a highfrequency linear probe Finally, the sonographer should be aware of the variable sensitivity of ultrasound in bedside assessment of appendicitis Thus nonvisualization of the appendix should be considered nondiagnostic rather than a negative study PROCEDURAL APPLICATIONS