Although positive oral contrast agents are used for the majority of abdominopelvic CT scans
in the United States, the quality of bowel opacification has not been compared between the
three major classes of positive oral contrast material (barium sulfate, ionic iodinated
contrast material, and non-ionic iodinate contrast material). This is a retrospective single
institution study of clinical records to show whether the uniformity of bowel opacification
is different between the three main types of positive CT oral contrast material used in the
United States (Barium sulfate, Diatrizoate, and Iohexol). The investigators will
retrospectively identify 250 patients each who received oral barium sulfate, diatrizoate, and
iohexol for CT scanning of the abdomen and pelvis (total 750 patients) and assess the quality
of bowel lumen opacification by the positive oral contrast agents.