Predictive Factors for Negative Outcomes in Initial Non-operative Management of Suspected Appendicitis

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. 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. 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. 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.