Background: Acute appendicitis has been reported to be managed with non-operative therapy at relatively high successful rate. However, risk factors for negative outcome have not been established.
Method: Three hundred eighty consecutive patients who underwent initial therapy for suspected appendicitis were reviewed. They were divided into three groups: operation group, the group successfully managed with non-operative therapy (success group), and the group required surgical conversion (failure group). Preoperative clinical data were compared among the groups and risk factors for negative outcomes were investigated.
Result: Thirteen patients were excluded due to contraindication for non-operative therapy. Of the remaining 367 patients, 143 patients (39.0%) were primarily treated with surgery, and 224 patients (61.0%) were initially managed with antibiotics. Among the 224 patients, 91 patients (40.6%) were refractory to antibiotics and converted to surgery after more than 24 h usage of antibiotics. Multivariate analysis revealed that elevated C-reactive protein (CRP) level (>4 mg/dL) and presence of appendicolith were significant risk factors for conversion. Morbidity rate showed no significant difference between the operative and failure groups.
Conclusion: Elevated CRP concentration and appendicolith may predict the negative outcome in non-operative management. However, immediate appendectomy can possibly be avoided at least 24 h without increasing morbidity under the usage of antibiotics.