Introduction It is recommended that all patients undergoing barium enema have a flexible sigmoidoscopy to exclude disease in rectum and sigmoid colon. With the introduction of CT colonoscopy (CT colon) is sigmoidoscopy still required for the investigation of patients with suspected colorectal cancer (CRC).1 We reviewed CT colon and flexible sigmoidoscopy results in our patients who underwent both procedures with a view to answering this question.
Methods The findings of CT colon in 520 consecutive patients were reviewed by a GI radiologist blinded to the findings at flexible sidmoidoscopy. The mean age of the population was 65 years old. Patients with inadequate bowel preparation for flexible sigmoidoscopy, colonoscopy, polypectomy, abnormal MRI or CT colon as first line investigation and more than 6 months period between CT colon and flexible sigmoidoscopy were excluded. Statistical analysis was performed with χ2 and Fisher test.
Results 332 patients were excluded for the reasons stated above. 188 patients were analysed. In 88% of these there was concordance between the results of CT colon and flexible sigmoidoscopy. Statistically significant (p<0.001) association was shown between detecting cancer by flexible sigmoidoscopy vs CT colon. The sensitivity and specificity of flexible sigmoidoscopy was 74% and 99% respectively [ppv—0.93, npv—0.94]. Flexible sigmoidoscopy did not identify six cancers which were revealed on CT colon. CT colon did not detect two cancers due to collapse colon and further investigation was recommended. There was statistical significant (p<0.05) association between bowel symptoms such as PR bleeding and iron deficiency anaemia and the diagnosis of bowel cancer in patients undergoing flexible sigmoidoscopy.
Conclusion CT colon should replace flexible sigmoidoscopy especially in elderly patients as first line investigation. Flexible sigmoidoscopy still has a role in those patients who found on CT colon to have a collapse left colon.
Competing interests None declared.
Reference 1. NICE clinical guideline. “The Diagnosis and Management of Colorectal Cancer”. Issued: November 2011.
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