Discriminating between simple and perforated appendicitis.

Background: Several studies have been performed in order to diagnose an acute appendicitis using history taking and laboratory investigations. The aim of this study was to create a model for the identification of a perforated appendicitis.

Methods: All consecutive patients who have undergone an appendectomy in the Reinier de Graaf hospital between January 1, 2007 and July 31, 2009, were included in a retrospective cohort study. Baseline patient characteristics, history and laboratory data were collected. Variables discriminating perforated from non-perforated appendicitis were identified using univariate and multivariable analyses.

Results: A total of 498 patients were included in the study. In the univariate analysis leukocyte count, C-Reactive Protein levels, Erythrocyte Sedimentation Rate levels, days of symptoms and temperature were identified as predictors of perforated appendicitis. The predicted probability (P) of a perforated appendicitis can be calculated from the following model: (P)=1/(1+e(-(-2.788+0.012 * CRP+0.207 * days with complaints))).

Conclusions: Perforation of appendicitis can be predicted from the CRP level and the duration of abdominal pain. These findings might influence the choice between conservative or surgical treatment of appendicitis, and could provide guidance in the early start of antibiotics.