Context Misdiagnosis of presumed appendicitis is an adverse outcome that leads
to unnecessary surgery. Computed tomography, ultrasonography, and laparoscopy
have been suggested for use in patients with equivocal signs of appendicitis
to decrease unnecessary surgery.
Objective To determine if frequency of misdiagnosis preceding appendectomy has
decreased with increased availability of computed tomography, ultrasonography,
Design, Setting, and Patients Retrospective, population-based cohort study of data from a Washington
State hospital discharge database for 85 790 residents assigned International Classification of Diseases, Ninth Revision
procedure codes for appendectomy, and United States Census Bureau data for
Main Outcome Measure Population-based age- and sex-standardized incidence of appendectomy
with acute appendicitis (perforated or not) or with a normal appendix.
Results Among 63 707 nonincidental appendectomy patients, 84.5% had appendicitis
(25.8% with perforation) and 15.5% had no associated diagnosis of appendicitis.
After adjusting for age and sex, the population-based incidence of unnecessary
appendectomy and of appendicitis with perforation did not change significantly
over time. Among women of reproductive age, the population-based incidence
of misdiagnosis increased 1% per year (P = .005).
The incidence of misdiagnosis increased 8% yearly in patients older than 65
years (P<.001) but did not change significantly
in children younger than 5 years (P = .17). The proportion
of patients undergoing laparoscopic appendectomy who were misdiagnosed was
significantly higher than that of open appendectomy patients (19.6% vs 15.5%; P<.001).
Conclusion Contrary to expectation, the frequency of misdiagnosis leading to unnecessary
appendectomy has not changed with the introduction of computed tomography,
ultrasonography, and laparoscopy, nor has the frequency of perforation decreased.
These data suggest that on a population level, diagnosis of appendicitis has
not improved with the availability of advanced diagnostic testing.