Electronic colonoscopy, it is possible to detect colorectal cancer, but there is a risk of missing the diagnosis. Colorectal cancer is usually detected using two types of electronic colonoscopy, sigmoidoscopy and total colonoscopy. Electronic colonoscopy allows direct visualization of the mucosa of the colon and removal of smaller, earlier tumors. Sigmoidoscopy is shorter than total colonoscopy, but because the terminal colon is not examined, there may be a risk of missed diagnoses. Sensitivity of sigmoidoscopy for detecting colon cancer has been reported to be 60% to 70%, but varies by age, gender, and race. Whole colonoscopy is highly sensitive. Currently reported sensitivities are about 85% to 96%. The sensitivity of total colonoscopy for detecting tumors larger than 10 mm is 89%~98%, but is less sensitive for tumors between 6 and 10 mm (74.6%~92.8%). If electronic colonoscopy is needed, timely consultation and standardized treatment are recommended.