Screening Methods

Colonoscopy

Examines inside the rectum and entire colon using a long, lighted tube called a colonoscope.

Every 10 years if normal

• The most complete screening method available, identifying and removing polyps in one session.

• Sedation is given to patient to minimize discomfort.

• Screens full colon.

• Depending on results may only need to be re-screened every 10 years.

• Typically requires 1 day of clear liquids & laxative preparation.

• Small risk of perforation or bleeding.

• May be expensive if your health insurance does not cover this procedure.

• Will need to set aside a day for procedure and have a ride home in order to leave the medical facility.

Computed Tomographic Colonography (virtual colonoscopy)

Uses x-rays and computers to take 2- or 3-dimensional images of your colon and rectum.

Every 5 years

• Can identify polyps that are >5mm before they turn into cancer.

• Usually does not require sedation.

• Identifies lesions in the entire colon and lower belly.

• Less invasive than a colonoscopy.

• Less risk of complications than colonoscopy.

• Polyps cannot be removed during the screening process -- will need to get a colonoscopy if test is positive.

• May be expensive.

• Requires liquid diet and bowel preparation beforehand.

• May miss smaller polyps.

• Not yet widely available.

Flexible sigmoidoscopy

Examines your rectum and the lower part of the colon with a lighted tube called a sigmoidoscope.

Every 5 years

• Can identify polyps before they turn into cancer.

• Usually does not require sedation.

• Moderate cost; covered by most insurance.

• Many primary care providers can do the test in their office.

• Can accurately find polyps in the lower part of the colon (where most polyps occur).

• Polyps cannot be removed during the procedure but they can be biopsied -- will need to get a colonoscopy if biopsy is positive for colorectal cancer.

• Requires enema preparation.

• Patients may find test uncomfortable or embarrassing.

• Small risk of perforation or bleeding.

• Does not screen the upper section the colon.

Double-contrast barium enema

Air and barium are pumped into your rectum. The solution will show any polyps or tumors on x-rays.

Every 5-10 years

• Less expensive than a colonoscopy.

• Does not require sedation.

• Identifies lesions in the entire colon.

• Accurate for finding abnormalities, such as narrowed areas or pockets or sacs in the intestinal wall.

• Polyps cannot be removed during the screening process -- will need to get a colonoscopy if test is positive.

• Requires laxative preparation.

• Patients may find test uncomfortable or embarrassing.

• Availability is decreasing; usually only for patients who cannot undergo colonoscopy.

Digital Rectal Examination

Doctor examines inside of rectum with a gloved finger, to feel for abnormalities

Once a year

• No advance preparation or dietary restrictions.

• The procedure does not cause significant pain.

• Less costly than other methods.

• Polyps usually cannot be identified during the exam -- will need to get a colonoscopy if abnormality is noted.

• Only checks the first 2-3 inches of the rectum and is dependent on examiner's technique.

• You may experience slight, momentary discomfort during the test.

• Included in standard physical examination.

Fecal occult blood test (FOBT)

Can detect small amounts of blood in the stool by submitting a portion of several bowel movements to your doctor for testing.

Once a year

• Inexpensive; covered by most insurance.

• Can be simple to complete.

• Can be completed in the comfort of your home.

• Cannot identify polyps, can detect signs of cancer.

• Will need to get a colonoscopy if test is positive.

• Patients may find test unpleasant.

• Requires strict adherence to the test protocol for the test to be accurate (restricted diet and multiple days of stool collection).

• High false positive rate -- non-cancerous conditions may also cause blood in the stool and not specific for human blood.

• May miss tumors that bleed in small amounts or not at all.

Stool DNA Test (sDNA)

Checks for changes to the cells in the colon by looking at DNA cells in the stool.

Screening interval uncertain -- discuss this with your healthcare professional

• No advance preparation or dietary restrictions.

• Can be completed in the comfort of your home.

• Non-invasive, painless, and simple.

• Results to date indicate the test is likely to be highly accurate.

• Cannot identify precancerous polyps, only indicates if you already have cancer.

• Not FDA approved.

• Will need to get a colonoscopy if test is positive.

• More expensive than other stool tests.