Colonoscopy and Sigmoidoscopy


(koh-luh-NAH-skuh-pee) lets the physician look inside your entire large intestine, from the lowest part, the rectum, all the way up through the colon to the lower end of the small intestine. The procedure is used to diagnose the causes of unexplained changes in bowel habits. It is also used to look for early signs of cancer in the colon and rectum. Colonoscopy
enables the physician to see inflamed tissue, abnormal growths, ulcers, bleeding, and muscle spasms. For the procedure, you will lie on your left side on the examining table. You will probably be given pain medication and a mild sedative to keep you comfortable and to help you relax during the exam. The physician will insert a long, flexible, lighted tube into your rectum and slowly guide it into your colon. The tube is called a colonoscope (koh-LON-oh-skope). The scope transmits an image of the inside of the colon, so the physician can carefully examine the lining of the colon. The scope bends, so the physician can move it around the curves of your colon. You may be asked to change position occasionally to help the physician move the scope. The scope also blows air into your colon, which inflates the colon and helps the physician see better.

If anything unusual is in your colon, like a polyp or inflamed tissue, the physician can remove a piece of it using tiny instruments passed through the scope. That tissue (biopsy) is then sent to a lab for testing. If there is bleeding in the colon, the physician can pass a laser, heater probe, or electrical probe, or inject special medicines, through the scope and use it to stop the bleeding.

Bleeding and puncture of the colon are possible complications of colonoscopy. However, such complications are uncommon. Colonoscopy takes 30 to 60 minutes. The sedative and pain medicine should keep you from feeling much discomfort during the exam. You will need to remain at the physician’s office for 1 to 2 hours until the sedative wears off.



A flexible sigmoidoscopy (SIG-moy-DAH-skuh-pee) exam is a short colonoscopy exam, limited to the lower one third of the colon. Sigmoidoscopy enables the physician to look at the sigmoid colon. Physicians may use this procedure to find the cause of diarrhea, abdominal pain, or constipation. They also use sigmoidoscopy to look for early signs of cancer in the colon and rectum. With sigmoidoscopy, the physician can see bleeding, inflammation, abnormal growths, and ulcers.

Sigmoidoscopy takes 10 to 20 minutes. During the procedure, you might feel pressure and slight cramping in your lower abdomen. You will feel better afterwards when the air leaves your colon.

The discovery of a polyp on flexible sigmoidoscopy necessitates a complete colon inspection with a colonoscope, since at least 30 percent of these patients will have additional polyps.


Indications for Colonoscopy and Flexible Sigmoidoscopy

According to the STOP Colon/Rectal Cancer Foundation:

  • Beginning at age 50, you should have a screening colonoscopy every 10 years. If you are completely asymptomatic (without any symptoms) and you have no history of colorectal disease, you still need to be screened.
  • Beginning at age 40 or earlier, you should have a colonoscopy if you have a personal or family history of benign colorectal polyps, colorectal cancer, ovarian cancer, uterine cancer, breast cancer, ulcerative colitis or Crohn’s disease.

According to the 2007 Medicare guidelines for colorectal cancer screening:

  • A colonoscopy is recommended once beginning at age 50, then once every 10 years.
  • For a patient with high risk factors (defined as: having a sibling, parent, or child with an adenomatous polypor colon cancer; a family history of adenomatous polyposis or hereditary colorectal cancer; or a personal history of adenomatous polyps, colorectal cancer, or Inflammatory Bowel Disease), a colonoscopy is recommended every 2 years (without regard to age).
  • A flexible sigmoidoscopy is recommended once beginning at age 50, then once prednisone every 4 years, for patients with normal risk factors; and can be done in lieu of screening colonoscopy. For patients with high risk factors (above), a screening colonoscopy should be performed.


Video References

1. Video: Colonoscopy exam and polyp removal – at the Mayo Clinic

2. Video: Colonoscopy Tutorial – The National Library of Medicine

3. Video: Sigmoidoscopy Tutorial – The National Library of Medicine

4. Video: Humor: How To Enjoy A Colonoscopy