The researchers assessed the accuracy of computed tomography (CT) and ultrasonography (US) in diagnosing acute appendicitis.
They reported their findings in the May issue of Archives of Surgery.
766 consecutive patients undergoing appendectomy for suspected appendicitis from 1995 to 1999, at a university tertiary care center, were enrolled in the study.
The main outcome measures were epidemiology of acute appendicitis and the roles of clinical assessment, CT, US, and laparoscopy.
The researchers found the negative appendectomy rate to be 15.7%, and the incidence of perforated appendicitis to be 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%), CT (84%), and US (81%).
The false-negative rates were 60% for CT and 76% for US.
Emergency department evaluation took a mean of 5.2 hours and was prolonged by CT or US (7.8 h and 6.4 h, respectively). The duration of emergency department evaluation did not affect the perforation rate. However, patients with postoperative complications had longer evaluations (mean, 8.0 h) than did those without (4.8 h).
|Mean time taken for emergency evaluation: 5.2 h|
With US: 6.4 h
With CT: 7.8 h
|Archives of Sugery|
Morbidity was found to be 9% - 6% for non-perforated cases and 20% for perforated cases.
76 patients had laparoscopic appendectomy, with a negative appendectomy rate of 42%, compared with 15% for open appendectomy. Laparoscopy, however, had minimal morbidity (1.3%) and correctly identified the abnormality in 92% of patients who had a normal-appearing appendix.
Dr Steven Lee, of the University of California, Sacramento, said on behalf of the group, "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," he concluded.