Quality indicators in screening colonoscopy for colorectal polyps and cancer

Abstract

Colorectal cancer is one of the commonest forms of malignant tumors all over the world and ranks second among the causes of cancer deaths in the majority of the developed countries. The prevention of colorectal cancer is an efficient measure leading to decreasing of colorectal cancer morbidity and mortality. Screening for colorectal cancer is aimed at detecting early cancer and pre-cancerous lesions. Colonoscopy is the leading and most effective method for the endoscopic diagnostics of colorectal adenomas and colorectal early cancer. In countries where the national screening programs for colorectal cancer are being implemented, there are special recommendations to reduce the risk of complications during the colonoscopy, define the standards and quality indicators in screening colonoscopy. The main quality indicators for screening colonoscopy include Adenoma Detection Rate — ADR, Polyp Detection Rate — PDR, Cecal Intubation Rate — CIR, Colonoscopy Withdrawal Time — CWT, quality of bowel preparation. The Adenoma Detection Rate (ADR) is the main quality indicator of colonoscopy. The European Society of Gastrointestinal Endoscopy (ESGE) recommends that the number of adenomas and cancers is recorded for all screening examinations. ESGE defines Adenoma Detection Rate as the number of colonoscopies at which one or more histologically confirmed adenomas is found divided by the total number of colonoscopies performed. Perhaps a more useful alternative would be the «adenoma detection index» (ADI) which signifies the total number of adenomas detected divided by the total number of colonoscopies performed. According to the guidelines of ESGE ADR should be at least 20%. The adenoma detection rate is closely related to the frequency of missed colorectal cancer. For each 1% increase in the ADR, the risk of «missed» CRC decreases by 3%. Higher ADRs are associated with a reduced risk of both proximal and distal cancer. ESGE recommends that the completion rate for all screening colonoscopies is audited and ESGE proposes a minimum standard of at least 90% for cecal intubation rate but excludes cases with obstructive cancer. These findings should be confirmed by the photographs of the appendiceal orifice and the ileocaecal valve. The complete examination of the colon and rectum is fundamental for any colorectal cancer screening program. The medial wall of the cecum between the appendiceal orifice and the ileocecal valve can not be visualized from a distance. Cecal intubation is defined as deep intubation into the cecum with the tip of the endoscope being able to touch the appendiceal orifice. The low level of CIR is associated with the high risk of interval proximal colon cancer. According to the ESGE guidelines, colonoscopy withdrawal time (CWT) should be ≥6 minutes at least in 90% of cases. CWT is directly related to the adenoma and polyp detection rate. If CWT is less than 6 minutes, ADR decrease. According to the ESGE guidelines the state of bowel cleansing should be rated as having “adequate” preparation at least in 90% of the examinations. The bowel cleansing is considered as adequate if it allows detection of polyps over 5 mm in size. Inadequate and poor bowel preparation increases colonoscope insertion time to the cecum, colonoscopy withdrawal time and significantly decreases polyp and adenoma detection rate.