Davis J, et al. - This retrospective chart review was undertaken to determine if C-reactive protein (CRP) and symptom duration could be used to improve diagnosis of appendicitis compared with white blood cell count (WBC) and absolute neutrophil count (ANC). A consecutive sample of all children < 18 years of age being assessed for appendicitis who had MRI ordered were involved. Five hundred thirty-nine patients have been identified. There are not appropriate characteristics of any laboratory test studied to be used alone. CRP adds marginal sensitivity beyond WBC and ANC when symptoms are > 1 day but with low specificity, making them of limited use.