Of the 829 patient data sets collected for this study, 103 lacked neutrophil counts and one lacked CRP. Neutrophil count was not routinely checked for every patient with abdominal pain in the care unit where this study was performed and thus was easily omitted by the surgeons. Some patients with RLQ pain were not included in the study for non-compliance of a minority of the surgeons, i.e., no returned data forms. This bias is not systematic because, e.g., time of admission did not affect inclusion of patients, but instead depended on the appointed surgeon.