Ultrasound of the Normal Appendix

Sonography now plays a vital role in noninvasive evaluation of patients with right lower quadrant pain. Sonography can differentiate appendicitis from other etiologies of pelvic pain, such as ovarian cysts, tubo-ovarian abscesses, inguinal hernias, and uterine pathologies. Successful demonstration of a normalsized appendix virtually excludes appendicitis in the patient with right lower quadrant pain. False-negative examinations may occur because of bowel gas interference, stool, perforation with decompression of the appendix, or inflammation of the appendix without abnormal enlargement. The purpose of this study was two-fold: to determine how often a normal-sized appendix is demonstrable in patients who do not have appendicitis; and to determine whether locating a normal appendix improves the negative predictive value for the absence of appendicitis.