Computed tomography and ultrasonography do not improve and may delay the diagnosis and treatment of acute appendicitis

Hypothesis: Computed tomography (CT) and ultrasonography (US) do not improv e the overall diagnostic accuracy for acute appendicitis. Design: Retrospective review. Setting: University tertiary care center. Patients: Seven hundred sixty-six consecutive patients undergoing appendect omy 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 per forated appendicitis was 14.6%. A history of migratory pain had the highest positive predictive value (91%), followed by leukocytosis greater than 12x 10 degrees /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 m ean +/- SD of 5.2 +/-5.4 hours and was prolonged by US or CT (6.4 +/- 74 h and 7.8 +/- 10.8 h, respectively). The duration of emergency department eva luation did not affect the perforation rate, but patients with postoperativ e complications had longer evaluations (mean +/- SD, 8.0 +/- 12.7 h) than d id those without (4.8 +/-3.3 h) (P=.04). Morbidity was 9.1%, 6.4% for nonpe rforated cases and 19.8% for perforated cases. Seventy-six patients had lap aroscopic appendectomy, with a negative appendectomy rate of 42.1%, compare d with 15.4% for open appendectomy (P < .001). Laparoscopy, however, had mi nimal 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 ins tead.