173 Retrospective Study Correlating Bowel Wall Thickening to Colonoscopy Findings

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INTRODUCTION: Colonic bowel wall thickening (BWT) on computed tomography (CT) scan is a common but nonspecific finding. It can correspond to an early pathological change, a mere artifact or may be due to inadequate distention of the colorectum (CR). The pattern of BWT can be indicative of malignant, inflammatory, or infectious process. However, the clinical relevance of colorectal thickening on CT is unclear, and if an endoscopic examination is warranted is yet to be determined. The main objective of this study is to assess the sensitivity (Sn) and specificity (Sp) of BWT on CT scan in identifying colorectal cancer (CRC) and to provide evidence to inform a cost-effective and clinically relevant diagnostic strategy. METHODS: This was a retrospective cohort chart review of 300 consecutive patients who had BWT described on CT scan of the abdomen (with or without oral contrast) AND who subsequently underwent a colonoscopy. The primary outcome was the Sp of BWT on CT in diagnosing CRC. Ratios of distributions were used to describe the cohort at baseline. The distribution of BWT was also calculated to describe the location of BWT in the different sections of the CR: Ascending (including the cecum), transverse, descending, sigmoid and rectum. The area under the curve (ROC) analysis was conducted to assess for the Sn and Sp of CT's bowel wall thickening in predicting colorectal masses. This was extrapolated to predict any pathology, including colitis, polyps, and diverticulosis. RESULTS: The mean age at diagnosis was 61.6. Only 3 patients (1.7%) reported a positive family history (hx) of CRC. 7 (4.1%) reported a prior hx of partial bowel resection and 11 patients (6.4%) reported a hx of IBD. The distribution of the BWT was as follows: Ascending colon 29.1%, Transverse colon 34.3%, descending colon 45.9%, sigmoid colon 61.0%, and rectum 18%. The CT ROC value in predicting a mass seen on endoscopy ranged between 0.491 and 0.524 in all 5 studied sections of the colon. This study suggests that the CT carries a very low accuracy as a diagnostic test for colorectal masses. CONCLUSION: In conclusion, this study demonstrates that despite common practice, the CT finding of bowel wall thickening remains a poor indicator of colorectal masses. Nonetheless, Gastroenterologists feel obliged to pursue endoscopic visualization of all CT scans with the finding of BWT for a variety of reasons, including defensive medical practices. Further studies might clarify which subgroups warrant further investigation.