Selection of Nonessential Intravenous Contrast Enhanced-Computed Tomography for Diagnosing Acute Appendicitis

Naoko Kondo¹⁾, Yoshimi Kitagawa^{1) 2)}, Tatsunari Satake³⁾, Toshihiko Mayumi^{2) 4)} and Hiroshi Kohno¹⁾

Department of Surgery¹⁾, Department of Emergency Medicine²⁾ and Department of Pathology³⁾,
Nagoya Ekisaikai Hospital
Department of Emergency and Critical Care Medicine, Nagoya University Graduate School of Medicine⁴⁾

Introduction: Since computed tomography (CT) has made acute appendicitis increasingly easy to diagnose correctly, intravenous contrast-enhanced CT (IV-CT) is increasingly used for this diagnosis. The purpose of this study is to clarify an indication of IV-CT and to eliminate unnecessary IV-CT. We studied whether IV-CT is necessary in all patients suspected of acute appendicitis, given the interval between onset and clinical diagnosis. Methods: IV-CT was performed in patient who had right lower quadrant abdominal pain or who had no pain but physical findings at right lower quadrant abdomen. We reviewed detailed medical records of 171 consecutive patients who underwent IV-CT followed by appendectomy within 24 hr. We compared Blumberg's sign, muscle guarding, body temperature, white blood cell count, and C reaction protein, dividing patients into 3 groups-half a day, in which the interval between onset and initial diagnosis was shorter than half a day; 1-day, in which the interval was longer than half a day but shorter than 1 day; and multiple-day, in which the interval exceeded 1 day. We also analyzed IV-CT findings for the abnormal appendix and the number of positive individual CT findings including abnormal appendix, calcified appendicolith, ascites, cecal wall thickening, and dilated intestines. Results: Muscle guarding was significantly common in the patients who had appendicitis among 1-day and multiple-day patients. In IV-CT, enlarged appendix was observed more frequently in those with appendicitis in all 3 groups. Positive individual CT findings were detected more often in multiple-day patients who had appendicitis. We found no significant difference among the other items. Conclusion: A patient diagnosed clinically later than half a day after onset and having muscle guarding should be strongly suspected having acute appendicitis, indicating that IV-CT is not needed in such patients.

Key words
computed tomography, appendicitis, muscle guarding

Reprint requests
Naoko Kondo Department of Surgery, Nagoya Ekisaikai Hospital
4-66 Shohnen-cho, Nakagawa-ku, Nagoya, 454-8502 JAPAN

Accepted
September 27, 2006

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