Colonoscopy is increasingly used to screen for colorectal neoplasms and to remove benign adenomatous polyps before they become cancerous. This study, conducted at a large community-based gastroenterology practice, examined the proposal that endoscopists who take more time to examine the colorectal mucosa—prolonging withdrawal of the scope—detect more neoplasms. Twelve experienced gastroenterologists performed a total of 7882 colonoscopies during a 15-month period; 2053 of them were screening exams in persons having their first colonoscopy. Detection rates were compared for practitioners whose colonoscopic withdrawal times were less than 6 minutes and 6 minutes or longer. Experts believe that at least 6 minutes are needed to adequately inspect the colon and rectum.
Nearly one in four of those examined (23.5%) were found to have adenomatous polyps. The mean withdrawal time was 6.3 minutes when no polyps were removed and 10.6 minutes when polyps were removed. Withdrawal times correlated closely with lesion detection rates, whether or not polyps or masses were manipulated. In cases where polyps were removed, withdrawal times correlated inversely with polyp size, and longer withdrawal times correlated positively with the removal of polyps less than 5 mm in diameter. Endoscopists taking 6 minutes or longer to withdraw the colonoscope had significantly higher rates of detection of all adenomas, advanced adenomas, and hyperplastic lesions. Those with relatively long withdrawal times detected nearly 4-fold more adenomas than endoscopists with relatively short withdrawal times. The rates of detection of advanced neoplasms were 6.4% and 2.6%, respectively, and of all neoplasms, 28.3% and 11.8%.
The findings in this observational study are preliminary and therefore should be cautiously interpreted. Nevertheless, they may inform future attempts to find ways of preventing colorectal cancer.