Systematic Review: Computed Tomography and Ultrasonography To Detect Acute Appendicitis in Adults and Adolescents

5 October 2004 | Volume 141 Issue 7 | Pages 537-546

Background: Although clinicians commonly use computed tomography or ultrasonography to diagnose acute appendicitis, the accuracy of these imaging tests remains unclear.

Purpose: To review the diagnostic accuracy of computed tomography and ultrasonography in adults and adolescents with suspected acute appendicitis.

Data Sources: The authors used MEDLINE, EMBASE, bibliographies, review articles, textbooks, and expert opinion to retrieve English- and non–English-language articles published from 1966 to December 2003.

Study Selection: The authors included prospective studies evaluating computed tomography or ultrasonography followed by surgical confirmation or clinical follow-up in patients at least 14 years of age with suspected appendicitis.

Data Extraction: One assessor (for non–English-language studies) or 2 assessors (for English-language studies) independently reviewed each article to abstract relevant study characteristics and results.

Data Synthesis: Twelve computed tomography studies and 14 ultrasonography studies met inclusion criteria. Computed tomography had an overall sensitivity of 0.94 (95% CI, 0.91 to 0.95), a specificity of 0.95 (CI, 0.93 to 0.96), a positive likelihood ratio of 13.3 (CI, 9.9 to 17.9), and a negative likelihood ratio of 0.09 (CI, 0.07 to 0.12). Ultrasonography had an overall sensitivity of 0.86 (CI, 0.83 to 0.88), a specificity of 0.81 (CI, 0.78 to 0.84), a positive likelihood ratio of 5.8 (CI, 3.5 to 9.5), and a negative likelihood ratio of 0.19 (CI, 0.13 to 0.27). Verification bias and inappropriate blinding of reference standards were noted in all of the included studies.

Limitations: The summary assessment of the diagnostic accuracy for both tests was limited by the small number of studies, heterogeneity among study samples, and poor methodologic quality in the original studies.

Conclusions: Computed tomography is probably more accurate than ultrasonography for diagnosing appendicitis in adults and adolescents. Prospective studies that apply gold standard diagnostic testing to all study participants would more reliably estimate the true diagnostic accuracy of these tests.

Editors' Notes Context Is computed tomography or ultrasonography better for diagnosing acute appendicitis? Contribution This meta-analysis summarized data from 22 prospective studies that compared results of computed tomography, ultrasonography, or both with surgical findings or clinical follow-up in patients with suspected appendicitis. Computed tomography findings (positive likelihood ratio, 13.3 [95% CI, 9.9 to 17.9]) increased the certainty of diagnosis more than did ultrasonography (positive likelihood ratio, 5.8 [CI, 3.5 to 9.5]). Cautions All studies had significant limitations that probably inflated estimates of diagnostic accuracy, such as inadequate blinding of the reference standard and pathologic verification of disease only in patients with positive test results. –The Editors

 

Author and Article Information

From the San Francisco Veterans Affairs Medical Center and University of California, San Francisco, San Francisco, California; and Harborview Medical Center, University of Washington, Seattle, Washington.

Acknowledgments: The authors thank Shyr-Chyr Chen, MD; Marc Horton, MD; Herman Kan, MD; Susan Walker, MD; Terry Gilliland, MD; Bernard Vermeulen, MD; and Scott Wise, MD, for providing the data on their original work. They also thank Bernard Birnbaum, MD, for reviewing the English-language literature retrieval results and Hubert J. Vesselle, MD, PhD, and Ken F. Linnau, MD, for assistance in translating French- and German-language publications.

Grant Support: Drs. Terasawa and Kohlwes were supported in part by the PRIME residency program, University of California, San Francisco, San Francisco, California. Dr. Terasawa was supported in part by a Grant-in-Aid for Postgraduate Medical Education and Training in Primary Care from the Ministry of Health, Labour, and Welfare, Japan. Dr. Blackmore was supported in part by the Agency for Healthcare Research and Quality (grant K08-HS11291). Dr. Bent was supported in part by the National Center for Complementary and Alternative Medicine (grant 1 K08-AT001338-01).

Potential Financial Conflicts of Interest: None disclosed.

Requests for Single Reprints: Teruhiko Terasawa, MD, Department of Clinical Research and Hematology, Nagoya National Hospital, 4-1-1 Sannomaru, Naka-ku, Nagoya, Japan 460-0001; e-mail, terasawa{at}nnh.hosp.go.jp.

Current Author Addresses: Dr. Terasawa: Nagoya National Hospital, 4-1-1 Sannomaru, Naka-ku, Nagoya, Japan 460-0001.

Drs. Bent and Kohlwes: San Francisco Veterans Affairs Medical Center, 4150 Clement Street, Box 111, San Francisco, CA 94121.

Dr. Blackmore: Harborview Medical Center, 325 Ninth Avenue, Box 359728, Seattle, WA 98104.

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