A flexible sigmoidoscopy is a procedure that is used to see the inside of the sigmoid colon and rectum – the last part of the large bowel. A thin flexible tube is passed into the back passage into the lower colon (sigmoid colon). It is similar to, but not the same as, a colonoscopy. A sigmoidoscopy only examines the sigmoid colon (the last third of the colon) whereas a colonoscopy examines the whole large bowel (colon).

A sigmoidoscopy can be used to identify early signs of cancer, and can help diagnose unexplained changes in bowel habits, abdominal pain, bleeding from the anus and weight loss.