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 mechanica l small-bowel obstruction, as opposed to paralytic ileus, during the i mmediate postoperative period may be difficult on the basis of clinica l and plain film radiographic findings. For this reason, we prospectiv ely evaluated the use of CT in this setting and compared it with the c linical and plain film evaluations as well as with various contrast ex aminations. SUBJECTS AND METHODS. Thirty-six postoperative patients wi th signs and symptoms of paralytic ileus or mechanical small-bowel obs truction were examined clinically and had plain abdominal radiographs. Based on the findings of these examinations, the surgeon assigned pat ients to one of the following categories: (1) paralytic ileus, (2) ind eterminate, (3) partial mechanical obstruction, or (4) complete mechan ical obstruction. CT scans were obtained within 24 hr of the initial d iagnostic studies, and patients were then recategorized according to t he above classification solely based on CT findings. Initial examinati on results were then compared with the CT results. In addition, the re sults of contrast studies, namely, enteroclysis and barium enema, perf ormed after CT small-bowel series, were evaluated, The gold standard f or diagnosis was laparotomy in 20 patients, clinical course and follow -up in 13 patients, and clinical course and contrast studies in the ot her three patients. RESULTS. CT was effective (sensitivity and specifi city, 100%) in distinguishing between postoperative ileus and complete mechanical small-bowel obstruction. The combined clinical and plain f ilm findings were often confusing and nondiagnostic (sensitivity, 19%) , CT was also valuable in diagnosing and distinguishing partial mechan ical small-bowel obstruction from paralytic ileus. Contrast studies (e nteroclysis) in four patients with partial mechanical small-bowel obst ruction were useful in grading the degree and severity of the obstruct ion. CONCLUSION. Our results suggest that in the immediate postoperati ve 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-bow el obstruction.