Does Inspection of Colonic Mucosa During Insertion Improve Adenoma Detection?

Successful implementation of colorectal screening programmes and improvement in colonoscopic technology have resulted in significant decrease in colorectal cancer incidence and mortality. Effectiveness of colonoscopy largely depends on detection and removal of adenomas before they become cancerous. Despite the vast improvement in colonoscopy training and technology, it remains as an imperfect tool. It has been reported that the adenoma miss rate during colonoscopy varies between 6-27% in clinical practice. Adenoma Detection Rate (ADR) is a surrogate marker of efficient colonoscopy. Researchers continue to explore various methods and technologies to improve adenoma detection such as frequent position changes, routine use of antispasmodics and devices to improve the mucosal visibility (third eye retro view scope, Transparent cap, Endocuff).

However, all the techniques are focused on the withdrawal stage of the examination. Colonic examination is traditionally performed with rapid passage of colonoscope to the caecum and a careful examination of mucosa is carried out during the withdrawal phase. Polyps are removed during the withdrawal phase. It is well known from expert opinion that some polyps are detected during the insertion phase rather than withdrawal phase especially in sigmoid and transverse colon. This could be due to different anatomical configuration of colon during insertion and withdrawal.

During insertion phase colonic mucosa is stretched and the folds are splayed due to the formation of loops and angulation hence affects the visualised area of the mucosa ahead of the colonoscope. During withdrawal, the colon is shortened and the adjacent folds are brought closer to each other. On withdrawal colon is much straighter. Therefore, it may expose different portions of colonic mucosal surface on insertion and withdrawal.

Flexible sigmoidoscopy Bowel cancer screening programme (Bowel Scope) has been successfully implemented since May 2013. Initial reports suggest ADR within Bowel Scope screening varies considerably.

Therefore, we propose a simple technique to improve ADR in Bowel Scope Screening.

RATIONALE FOR CURRENT STUDY

Recent report suggests that ADR within Bowel Scope screening (BSS) varies considerably. We propose a small technical alteration to improve ADR in BSS. A recent prospective trial highlighted that if polypectomy was performed only during Withdrawal Phase (WP) when compared to performing careful inspection and polypectomy during Inspection Phase (IP) plus WP, polyps could be missed in about 7% of patients. We hypothesised that careful inspection and polypectomy during both phases would be complementary and it would increase ADR by complete visualisation of recto sigmoid mucosa during Bowel Scope.