A colonoscopy is the most accurate method of diagnosing colorectal diseases by directly examining the colon using light and flexible tubes because the physician can directly observe the areas of bleeding and surface of lesions to identify tissue conditions.
During the colonoscopy, a biopsy can be also taken.
You can also get a colonoscopy under conscious sedation (sedative colonoscopy) that injects a sedative only working for a short period of time in order to take an examination in a comfortable and sleep-like state.
On the day before the test, the examinee should eat lightly for the dinner with porridge and take a purgative medicine to remove any remaining excreta from the colon.

In most cases, during the early stages of colon cancer, there are often no signs or symptoms, and if the symptoms appear, the disease progresses.

Approximately 35% of colon cancer (approximately 75% of rectal cancer) can be diagnosed only with a digital rectal examination. For those over the age of 40, a digital rectal examination is recommended every year.
In addition to the digital rectal examination, colon double contrast radiography, and sigmoidoscopy can be conducted. Among them, the colonoscopy is recommended as the most effective and accurate test for colon cancer diagnosis as it can observe the entire colon and can be performed simultaneously with the biopsy.