Computed Tomography and Ultrasonography Do Not Improve and May Delay the Diagnosis and Treatment of Acute Appendicitis

Abstract

HYPOTHESIS: Computed tomography (CT) and ultrasonography (US) do not improve the overall diagnostic accuracy for acute appendicitis. DESIGN: Retrospective review. SETTING: University tertiary care center. PATIENTS: Seven hundred sixty-six consecutive patients undergoing appendectomy for suspected appendicitis from January 1, 1995, to December 31, 1999. MAIN OUTCOME MEASURES: Epidemiology of acute appendicitis and the roles of clinical assessment, CT, US, and laparoscopy. RESULTS: The negative appendectomy rate was 15.7%, and the incidence of perforated appendicitis was 14.6%. A history of migratory pain had the highest positive predictive value (91%), followed by leukocytosis greater than 12 x 10(9)/L (90.1%), CT (83.8%), and US (81.3%). The false-negative rates were 60% for CT and 76.1% for US. Emergency department evaluation took a mean +/- SD of 5.2 +/- 5.4 hours and was prolonged by US or CT (6.4 +/- 7.4 h and 7.8 +/- 10.8 h, respectively). The duration of emergency department evaluation did not affect the perforation rate, but patients with postoperative complications had longer evaluations (mean +/- SD, 8.0 +/- 12.7 h) than did those without (4.8 +/- 3.3 h) (P =.04). Morbidity was 9.1%, 6.4% for nonperforated cases and 19.8% for perforated cases. Seventy-six patients had laparoscopic appendectomy, with a negative appendectomy rate of 42.1%, compared with 15.4% for open appendectomy (P<.001). Laparoscopy, however, had minimal morbidity (1.3%) and correctly identified the abnormality in 91.6% of patients who had a normal-appearing appendix. CONCLUSIONS: Migratory pain, physical examination, and initial leukocytosis remain reliable and accurate in diagnosing acute appendicitis. Neither CT nor US improves the diagnostic accuracy or the negative appendectomy rate; in fact, they may delay surgical consultation and appendectomy. In atypical cases, one should consider the selective use of diagnostic laparoscopy instead.