CT of Small-Bowel Ischemia Associated with Obstruction in Emergency Department Patients: Diagnostic Performance Evaluation
Shannon P. Sheedy, MD ; Frank Earnest, IV, MD ; Joel G. Fletcher, MD ; Jeff L. Fidler, MD ; Tanya L. Hoskin, MS
1 From the Division of Abdominal Imaging, Department of Radiology (S.P.S., F.E., J.G.F., J.L.F.) and Division of Biostatistics, Department of Health Sciences Research (T.L.H.), Mayo Clinic College of Medicine, Mayo W2, 200 First St SW, Rochester, MN 55905. Received June 8, 2005; revision requested August 3; revision received October 12; accepted November 14; final version accepted February 20, 2006.
PURPOSE: To retrospectively evaluate the diagnostic performance of computed tomography (CT) for detection of small-bowel ischemia in emergency department patients with abdominal pain and to compare the prospective interpretation with a retrospective interpretation by using surgical or pathologic findings as the reference standard.
MATERIALS AND METHODS: The HIPAA–compliant study was approved by the institutional review board, and patients consented to research authorization. Sixty patients (61 examinations) (25 male, 35 female patients; median age, 67 years; range, 0.9–89.7 years) with acute abdominal pain underwent immediate abdominal and pelvic CT and subsequent surgery of the small bowel within 7 days of CT. Prospective radiologic reports were reviewed for diagnosis of small-bowel obstruction and ischemia. Two gastrointestinal radiologists performed blinded, independent, retrospective review of the CT studies with no clinical data other than presence of acute abdominal pain. The reviewers categorized CT signs of obstruction and ischemia and estimated diagnostic certainty. Discordant findings were resolved by consensus review by a third gastrointestinal radiologist. CT interpretations were compared with prospective interpretations and surgical or pathologic findings. Sensitivity and specificity estimates with confidence intervals were calculated. Fisher exact and 2 tests were used to assess associations between CT signs and the diagnosis of ischemia; statistics were used to estimate agreement between readers.
RESULTS: In 27 (44%) of 61 CT studies, small-bowel ischemia was surgically or pathologically confirmed. Sensitivity and specificity for the diagnosis of ischemia were, respectively, 14.8% and 94.1% for prospective interpretations, 29.6% and 91.2% for reader 1, 40.7% and 85.3% for reader 2, and 51.9% and 88.2% for the consensus review. Decreased segmental enhancement was the most specific sign for small-bowel ischemia (P = .001), and its recognition would have improved the diagnostic performance of all readers. There was a significant association of the small-bowel feces sign with the presence of small-bowel ischemia (P = .046).
CONCLUSION: Diagnostic performance assessment of CT for the diagnosis of small-bowel ischemia revealed poor prospective interpretation sensitivity.