To the Editor: The editorial by Viiala and Olynyk on screening flexible sigmoidoscopy (FS)1 is a welcome reminder that there are alternative colorectal neoplasia (CRN) screening strategies to the Australian National Health and Medical Research Council’s preferred option of annual faecal occult blood testing. The availability of tests for CRN screening raises the issue of whether screening tests should be dictated by government or professional bodies, or requested by the consumer. FS and colonoscopy remain potential alternatives to faecal occult blood testing in Australia, as reflected by US screening guidelines2 and recent local data.1,3

However, it is unreasonable for Viiala and Olynyk to compare the risks of screening FS (generally diagnostic only) in average-risk subjects (perforation rate, 1/50 000) with the risks of colonoscopy (both diagnostic and therapeutic) in Western Australian tertiary hospital outpatients with symptoms or other risk factors for CRN (perforation rate 1/1000).

Firstly, it is important to recognise that the perforation risk associated with screening FS comes not just from the diagnostic screening test (1/50 000), but also from follow-up colonoscopy and subsequent polypectomy in patients with distal adenomas seen on FS.

Secondly, in the WA tertiary hospital cohort,4 the estimated perforation rate for diagnostic colonoscopy is about 1/2800 (and about 1/420 for colonoscopy accompanied by polypectomy). Asymptomatic subjects having screening colonoscopy are likely to have a lower risk than patients with symptoms or other significant comorbidities having investigative colonoscopy. Recent data from colonoscopic screening programs (which include subjects having polypectomy) have shown an overall perforation rate of less than 1/3000.5

Medical practitioners arranging colonoscopy, and people having this procedure, should be informed about the risks involved and, importantly, be aware that these risks are likely to vary according to the setting in which colonoscopy is performed.