3. Potential subjects who fail one or more inclusion or meet one or more exclusion criteria are recorded in electronic research log with reason for exclusion but are not asked to participate in study. Recorded information includes age (if greater than 89, will simply be recorded as "greater than 89"), gender, race/ethnicity, date, and reason for exclusion. No identifiers are recorded for these patients. The purpose of this information is to allow comparison of the enrolled group with all patients with abdominal pain undergoing CT. This will be part of a CONSORT flow diagram, allowing readers to understand potential selection bias and to understand the probable clinical population in the context of all emergency department's (ED) patients undergoing abdominal CT.