Why does the clinical diagnosis fail in suspected appendicitis?

Objective: To identify systematic errors in surgeons' estimations of the im portance of diagnostic variables in the decision to explore patients with s uspected appendicitis. Design: Prospective case series. Setting: Two emergency departments, Sweden. Patients: 496 patients with suspected appendicitis on admission, of whom 19 4 had a correct operation for appendicitis and 59 had a negative exploratio n. Main outcome measures: Predictors of a negative exploration expressed as th e odds ratio (OR) for negative exploration. Variables influence on the deci sion to operate, expressed as the OR for operation, compared with the true diagnostic importance, expressed as the OR for appendicitis. Results: Predictors of negative explorations were high ratings in variables describing pain and tenderness (patient's perceived pain, abdominal tender ness, rebound tenderness, guarding or rectal tenderness), weak or absent in flammatory response, female sex, long duration of symptoms and absence of v omiting, with OR of 1.8-3.0. Pain and tenderness had too strong an influenc e on the decision to operate whereas the lack of an inflammatory response, no vomiting, and long duration of symptoms were not given enough attention. There was no sex difference in the proportion of patients with non-surgica l abdominal pain (NSAP) who were operated on, but NSAP was more common and appendicitis less common among women, leading to a larger proportion of neg ative appendicectomies among women. Conclusion: Negative explorations in patients with suspected appendicitis a re related to systematic errors in the clinical diagnosis with too strong a n emphasis on pain and tenderness, and too little attention paid to duratio n of symptoms and objective signs of inflammation. Rectal tenderness is not a sign of appendicitis. The risk of diagnostic errors is similar in men an d women.