Unfortunately, the early stages of colorectal cancer may not produce any symptoms. That is why regular screening tests are urged even for people who are feeling well.

But as a colorectal polyp develops into a tumor, it may cause symptoms that include:

• Bleeding from the rectum.
• Blood in the stool or toilet after a bowel movement.
• A change in the shape of the stool (i.e. narrowing).
• Abdominal cramps.
• A feeling that the bowel hasn't emptied properly.

Experts say that either of the first two symptoms, or persistance of the other symptoms for more than a couple of weeks, should prompt an immediate visit to your doctor.

Although the appearance of these symptoms does not necessarily mean that you have colorectal cancer, it is important to find out what is causing them, so that a diagnosis can be made and an appropriate treatment program can be started.

A variety of tests are used to screen for colorectal cancer.

Fecal Occult Blood Test (FOBT):

The fecal occult blood test (FOBT) detects blood that is occult (not visible) in a stool sample. Blood vessels at the surface of colorectal polyps or adenomas or cancers are often easily damaged by the passage of feces, and may intermittently release a small amount of blood into the feces. While there rarely is enough bleeding to turn the stool red, the FOBT can detect the blood through a chemical reaction. A positive test signals the need for a colonoscopy to determine if there is a cancer, polyp or some other cause.

Those having an FOBT will receive a test kit with instructions on taking a stool sample at home. Certain foods or drugs that can affect the test need to be avoided for up to seven days before you take the stoll sample. The kit with the sample is then returned to the doctor's office or a medical laboratory for testing.

By itself, FOBT finds about one-quarter of all colorectal cancers.

Flexible Sigmoidoscopy:

Flexible sigmoidoscopy is a screening procedure that uses a flexible hollow, lighted tube -- about the thickness of a finger -- inserted through your rectum to visually inspect the rectal wall and part of the colon. Because it is only around 2 feet long, the doctor is able to see less than half of the colon.

Before the sigmoidoscopy, the patient needs to take an enema to clean out the lower colon. If a polyp or tumor is detected with this test, the patient is referred for a full colonoscopy.

Colonoscopy:

Colonoscopy is a screening procedure that uses long version of a sigmoidoscope that is inserted through the rectum up into the colon and allows the doctor to see the internal wall of the rectum and the lining of the entire colon

The colonoscope is also connected to a video camera and video display monitor so the doctor can closely examine the inside of the colon.

If a small polyp is found, the doctor generally will remove it by passing a wire loop through the colonoscope to cut the polyp from the wall of the colon with an electrical current. The polyp can then be sent to a lab to be checked under a microscope to see if it has any areas that have changed into cancer.

If the doctor sees a large polyp or tumor or anything else abnormal, a small piece of tissue will be taken out through the colonoscope to be biopsied.

Prior to a colonoscopy, the patient needs to take laxatives and an enema to clean the colon so there will be no stool to block the view. The colonoscopy may be done in a hospital outpatient department, in a clinic, or in a doctor's office.

Virtual colonoscopy:

In this procedure, air is pumped into the colon to distend it and a special CT scan called helical CT or spiral CT is performed. No contrast agent is required.

The virtual colonoscopy is viewed as more accurate than the barium enema but not quite as good as a standard colonoscopy for finding smaller polyps. The test can be done quickly, with no sedation, and at a lower cost than colonoscopy.

Virtual colonoscopy is still widely regarded by many as experimental and is currently not included among the tests recommended by the American Cancer Society for early detection of colorectal cancer.

Double-Contrast Barium Enema:

In this procedure also called barium enema with air contrast, the patient is given an enemy containing barium sulfate. When the colon is about half full of barium, air is pumped into the colon to make it expand. A series of X-rays of the colon and rectum are then taken producing the best pictures of the lining of the colon.

Prior to a double-contrast barium enema, the patient nees to take laxatimes and an enemy to clean the colon.

Digital Rectal Examination:

The digital rectal examination involves a doctor inserting a lubricated, gloved finger into the rectum to feel for abnormal areas. This simple test can detect masses in the anal canal or lower rectum. But since the doctor can only reach a limited area, this test -- often included as part of a routine physical examination -- is not recommended as a stand-alone screening method for colorectal cancer.

All information provided in this site is offered for educational purposes only, and it is not intended nor implied to be a substitute for professional medical advice. Always consult your own physician or healthcare provider with any questions you may have regarding a medical condition.