DISTINCTION BETWEEN POSTOPERATIVE ILEUS AND MECHANICAL SMALL-BOWEL OBSTRUCTION - VALUE OF CT COMPARED WITH CLINICAL AND OTHER RADIOGRAPHIC FINDINGS

OBJECTIVE. The expeditious diagnosis of complete and partial mechanical small-bowel obstruction, as opposed to paralytic ileus, during the immediate postoperative period may be difficult on the basis of clinical and plain film radiographic findings. For this reason, we prospectively evaluated the use of CT in this setting and compared it with the clinical and plain film evaluations as well as with various contrast examinations. SUBJECTS AND METHODS. Thirty-six postoperative patients with signs and symptoms of paralytic ileus or mechanical small-bowel obstruction were examined clinically and had plain abdominal radiographs. Based on the findings of these examinations, the surgeon assigned patients to one of the following categories: (1) paralytic ileus, (2) indeterminate, (3) partial mechanical obstruction, or (4) complete mechanical obstruction. CT scans were obtained within 24 hr of the initial diagnostic studies, and patients were then recategorized according to the above classification solely based on CT findings. Initial examination results were then compared with the CT results. In addition, the results of contrast studies, namely, enteroclysis and barium enema, performed after CT small-bowel series, were evaluated, The gold standard for diagnosis was laparotomy in 20 patients, clinical course and follow-up in 13 patients, and clinical course and contrast studies in the other three patients. RESULTS. CT was effective (sensitivity and specificity, 100%) in distinguishing between postoperative ileus and complete mechanical small-bowel obstruction. The combined clinical and plain film findings were often confusing and nondiagnostic (sensitivity, 19%), CT was also valuable in diagnosing and distinguishing partial mechanical small-bowel obstruction from paralytic ileus. Contrast studies (enteroclysis) in four patients with partial mechanical small-bowel obstruction were useful in grading the degree and severity of the obstruction. CONCLUSION. Our results suggest that in the immediate postoperative period, CT is the method of choice for diagnosing mechanical small-bowel obstruction and distinguishing it from paralytic ileus. Contrast studies are useful in further evaluating partial mechanical small-bowel obstruction.