A flexible sigmoidoscopy is a test in which your doctor examines the lining of the lowermost portion of your large intestine, or colon. The colon is typically 5 or 6 feet long. The last portion, just above the rectum, is called the sigmoid colon. The test is basically an abbreviated colonoscopy. It is is similar to a colonoscopy in that the patient must prepare by cleaning out the colon, this time by using either oral laxatives or enemas. The patient may or many not be sedated for the procedure. See ‘Colonoscopy’ for further details.