Efficacy of CT in distinguishing small-bowel obstruction from other causes of small-bowel dilatation.

OBJECTIVE: Dilatation of the small bowel is a common finding on plain abdominal radiographs. In such cases, it is often difficult to determine if the cause of the dilatation is small-bowel obstruction, paralytic ileus, or another intraabdominal disorder. Accordingly, we studied the efficacy of CT in making this distinction.

MATERIALS AND METHODS: The medical records of 75 patients with small-bowel dilatation seen on CT scans (more than three segments > 2.5 cm in diameter) were reviewed. The patients were divided into three groups (obstruction [27 patients], other surgical diagnosis [16 patients], and no surgery [32 patients]) on the basis of clinical course, findings at surgery, or both. CT scans were retrospectively evaluated by two gastrointestinal radiologists who did not know the results of the chart review. They evaluated the images with regard to the following specific criteria for obstruction: presence/continuity of duodenal, small-bowel, and colonic dilatation; presence of air-fluid levels; amount of intestinal fluid; presence of prestenotic dilatation; presence of transition zone; and cause of obstruction. In addition, each radiologist gave an overall impression regarding the presence or absence of obstruction (criteria not specified to the observers) and its site, or other cause of bowel dilatation. The CT interpretations of each of the radiologists were compared with the patients' subsequent clinical course.

RESULTS: Observer A was correct in 89%, 88%, and 72% of cases in the obstruction, other surgical diagnosis, and no surgery groups, respectively. Observer B was correct in 78%, 81%, and 69% of cases in the obstruction, other surgical diagnosis, and no surgery groups, respectively. Observer agreement regarding the proposed criteria for obstruction ranged from 65% to 91%. For both observers, only the presence of continuous small-bowel dilatation, prestenotic dilatation, and a transition zone correlated significantly with the presence of small-bowel obstruction.

CONCLUSION: CT can be a useful test for evaluating small-bowel dilatation and can aid both the diagnosis of small-bowel obstruction and its differentiation from other conditions resulting in small-bowel dilatation.