Operator-dependent techniques for graded compression sonography to detect the appendix and diagnose acute appendicitis.

OBJECTIVE: The objective of our prospective study was to evaluate the value of various operator-dependent techniques that allow graded compression sonography to detect normal or abnormal vermiform appendix.

SUBJECTS AND METHODS: A total of 877 subjects were included in this study. This sample population consisted of two groups: 202 control subjects and 675 patients who were suspected of having acute appendicitis. If detection of the appendix failed after a sufficient number of trials using graded compression scanning, appropriate operator-dependent techniques were used to help graded compression scanning to increase the detectability of the appendix further. The detection rate for the appendix in both groups and the diagnostic accuracy for acute appendicitis were obtained.

RESULTS: The initial graded compression sonography examination depicted the appendix in 170 (84%) of 202 subjects in the control group and 601 (89%) of the 675 patients in the patient group. We then added operator-dependent techniques to graded compression sonography for the remaining patients in whom the appendix could not be detected. The additional use of the posterior manual compression technique, low-frequency convex transducer, upward graded compression technique, or left oblique lateral decubitus change of body position allowed graded compression sonography to depict the appendix in an additional 10, eight, six, and four patients in the control group, respectively, and in an additional 27, 23, 11, and seven patients in the patient group. The number of identified appendixes was increased to 198 (98%) of the 202 patients in the control group and to 669 (99%) of the 675 patients in the patient group. Graded compression sonography with operator-dependent techniques in the patient group yielded a sensitivity of 99% (319/321 patients), specificity of 99% (350/354), and an accuracy of 99% (669/675) for acute appendicitis.

CONCLUSION: The addition of various operator-dependent techniques to graded compression sonography is useful for allowing improved visualization of both normal and abnormal appendixes.