Screening exams are a powerful tool in the fight against colorectal cancer. Regular screenings enable physicians to detect cancer early and to identify and remove polyps, growths of tissue on the lining of the colon or rectum that can potentially become cancerous.
Fecal Occult Blood Test
The fecal occult blood test (FOBT) is used to find small amounts of blood in the stool (not necessarily visible to the naked eye), which suggests the presence of polyps or cancer. This is because blood vessels at the surface of polyps or cancers are often damaged during the passage of feces, and bleed a small amount of blood into the stool.
Individuals are provided a kit to take home that has instructions on how to take stool samples. These stool samples are examined in the lab for traces of blood. A positive result requires further evaluation.
Fecal Immunochemical Test
The fecal immunochemical test (FIT) is a newer test to find blood in the stool. The test is essentially performed like a fecal occult blood test (FOBT), but the results tend to be more accurate.
A sigmoidoscope is a slender, flexible tube about the thickness of a finger that has a camera at the tip. It is inserted into the lower part of the colon through the rectum. The sigmoidoscope provides doctors with a view of the inner wall of the rectum and lower colon, allowing them to search for polyps or cancerous tissue. The tube is about two feet long so doctors can examine half of the colon. The test is performed in the physician’s office or in the hospital as an outpatient procedure and can be uncomfortable, but is generally not painful.
A colonoscope is the same as a sigmoidoscope but longer, enabling doctors to examine the entire colon. It is inserted into the body through the anus and gently guided through the rectum and colon. Patients are administered sedatives during the exam to keep them comfortable and relaxed. The test is usually done in the hospital as an outpatient procedure.
The colonoscope provides the doctor with magnified images of the inner wall of the colon and rectum. If a polyp is found during the examination, instruments can be passed through the colonoscope to remove polyps or tissue samples. The lab will check the extracted tissue samples for the presence of cancer cells.
Prior to the exam, patients will need to prepare their bowels. This includes following a special diet and using laxatives to clean out the bowels.
Some patients may be eligible for a virtual colonoscopy, which uses advanced CT technology and computer software to produce images of the colon.
Double Contrast Barium Enema
Prior to taking an x-ray, the colon is filled with air and a white, chalky liquid called barium. The barium and air show an outline of the colon, rectum, and any polyps or abnormal tissue on the x-ray.
If screening exams suggest the presence of cancer, advanced imaging techniques such as an ultrasound, MRI, PET scans and CT scans are used to determine if the cancer has spread to other organs and tissues.