Colon Cancer Prevention Sigmoidoscopy Colonoscopy

To check for colon cancer and catch it in an early stage, your doctor will likely want you to undergo regular colon cancer screenings. During these screenings, your doctor will check for abnormalities, such as polyps that have the potential to grow into cancerous tumors and asymptomatic tumors (growths that aren’t causing any symptoms).

Your doctor might perform a variety of tests to screen for colon cancer, including a sigmoidoscopy and a colonoscopy.


During a flexible sigmoidoscopy, your doctor will use a slender, flexible and hollow lighted tube called a sigmoidoscope in conjunction with a video camera and a monitor to examine the lower part of your colon. In general, the procedure is performed in a doctor’s office.

To begin the test, your doctor will insert the sigmoidoscope, which is about the size of an adult human’s finger, into your rectum and will then direct it into the lower portion of your colon. Next, he will examine the inside of your colon and rectum using the video monitor.

If your doctor sees a small polyp, he will likely remove it at this time. If he sees a polyp that he thinks is precancerous, however, or if he sees colon cancer, he will likely want you to undergo a colonoscopy to check for polyps or cancer in other portions of the colon.

While many people feel uncomfortable during a sigmoidoscopy, patients should not experience pain during the process. After the procedure, a person can expect cramping, gas and watery stools.

Removing Small Polyps During Colon Cancer Tests

During a sigmoidoscopy or a colonoscopy, your doctor may choose to remove small polyps. This is done because polyps can turn into cancer.

To remove the polyp, your doctor will pass a wire tube through the scope being used and will use an electrical current to cut the polyp from the lining of the colon or rectum. Once removed, your doctor will test the polyp to see if it is cancerous. The procedure of testing tissue for cancer is known as a biopsy.


During a colonoscopy, your doctor will use a colonoscope to examine your rectum and your colon in its entirety. A colonoscope is basically just a longer version of a sigmoidoscope. Like the sigmoidoscope, the colonoscope is connected to a video camera and a monitor, allowing your doctor to view the lining of the rectum and colon as he checks for cancerous growths and polyps.

During the procedure, your doctor may remove a small polyp if he finds one. If he finds large polyps or other abnormalities, he will likely remove only a small section of the tissue for biopsy.

A colonoscopy can be performed either in a hospital’s outpatient center or in its ambulatory care center. Before the procedure, you will receive a sedative that will make you more comfortable during the test. This sedative will most likely be administered via an IV.

In general, a colonoscopy will take between 15 and 30 minutes, unless polyps need to be removed.

Colonoscopy and Sigmoidoscopy Risks

Both colonoscopies and sigmoidoscopies are considered to be relatively safe procedures. Sometimes, however, the scopes used can puncture the lining of the rectum or colon, causing a perforation. This serious complication sometimes requires surgery in order to be repaired.

Preparing for a Sigmoidoscopy or Colonoscopy

Before colon cancer screening, your doctor may ask you to follow certain instructions. For instance, prior to undergoing a sigmoidoscopy, you may need to have an enema to clean out your lower colon.

To prepare for a colonoscopy, take a laxative the day before the procedure. Like a sigmiodoscopy, a colonoscopy may also require that you have an enema the morning of the test to clear out your colon. You will also need to avoid solid foods the day before and consume only clear liquids, such as:

  • apple juice
  • clear broths
  • ginger ale
  • water.

Your doctor will likely provide you with a list of items that you should avoid prior to having a colonoscopy.


American Cancer Society, Inc. (2007). Can Colorectal Polyps and Cancer Be Found Early? Retrieved October 9, 2007, from the American Cancer Society Web site: CRI_2_4_3X_Can_colon_and_rectum_cancer_be_found_early.asp.

Johnson, Brett Andrew (January 15, 1999). Flexible Sigmoidoscopy: Screening for Colorectal Cancer. Retrieved October 9, 2007, from the American Academy of Family Physicians Web site: