BACKGROUND: Abdominal pain is often evaluated using imaging, most often with computed tomography (CT). While CT is sensitive and specific for certain diagnoses, small bowel thickening is a nonspecific finding on CT with a broad differential diagnosis including infection, inflammation, ischemia and neoplasm.METHOD: A review of medical records of patients who underwent CT scans of the abdomen and pelvis over a one-year period and exhibited small bowel thickening were retrospectively evaluated to determine the final diagnosis.RESULTS: The etiologies of small bowel thickening on CT were as follows: infection (113 of 446 [25.34%]); reactive inflammation (69 of 446 [15.47%]); primary inflammation (62 of 446 [13.90%]); small bowel obstruction (38 of 446 [8.52%]); iatrogenic (33 of 446 [7.40%]); neoplastic (32 of 446 [7.17%]); ascites (30 of 446 [6.73%]); unknown (28 of 446 [6.28%]); ischemic (24 of 446 [5.38%]); and miscellaneous (17 of 446 [3.81%]).CONCLUSION: Infectious and inflammatory (primary or reactive) conditions were the most common cause of small bowel thickening in the present series; these data can be used to formulate a more specific differential diagnosis.