Evaluation of flexible sigmoidoscopy as an investigation for "left sided" colorectal symptoms.

BACKGROUND Colonoscopy is the best way of imaging the colon with concurrent biopsy and treatment. However it is expensive, requires full bowel preparation, and carries a risk of complications. Flexible sigmoidoscopy is an alternative way to investigate symptoms that raise the suspicion of a lesion of the rectum or left colon. AIM OF THE STUDY To evaluate flexible sigmoidoscopy as the main investigation for "left sided" colorectal symptoms. METHODS The clinical records of 317 patients who were assessed at a colorectal specialist clinic and were thought to have a suspicion of a lesion of the rectum or left colon were retrospectively reviewed. All patients had flexible sigmoidoscopy as the primary investigation. Primary outcome was the diagnostic yield of flexible sigmoidoscopy and secondary outcomes were any additional colonic investigations required, failure rates, and complication rates. RESULTS Three hundred and sixteen patients who had flexible sigmoidoscopy with the above criteria were retrospectively analysed. Twenty four procedures (7.6%) had to be abandoned because of poor bowel preparation. The examination was considered complete when it reached the splenic flexure, which was the case in 205 cases (65%). In 137 flexible sigmoidoscopies (43.3%) there were no abnormal findings. Of the remaining 179 a carcinoma of the rectum or colon was found in 28 cases (8.8%) and one or more polyps was found in 57 (18%) cases. On the basis of the findings it was calculated that 31% of the patients would require an additional investigation for further imaging of the right colon. DISCUSSION Although flexible sigmoidoscopy has a high yield of pathologies when carried out by a specialist colorectal clinic, the presence of those pathologies makes the full imaging of the whole colon with an additional investigation necessary. Therefore the cost efficiency of flexible sigmoidoscopy is questionable. Although flexible sigmoidoscopy is indicated for certain patients, it cannot replace colonoscopy as the main investigation used by a specialist colorectal clinic.