Colonoscopy is a diagnostic test that uses a flexible scope with a camera to inspect the insides of the colon and rectum.
The colon is the first 5 to 6 feet of the large intestine. The rectum is the term for the last 6 inches of the large intestine, which ends at the anus.
Doctors use a colonoscopy to screen for colon cancer, find and remove polyps, diagnose ulcers, and determine the cause of unusual abdominal and bowel symptoms.
A colonoscopy enables doctors to view the entire length of the colon. Virtual colonoscopy is another test used to screen the lower intestine, but it uses x-rays.
Sedation or anesthesia is not required during a virtual colonoscopy, but this test cannot show the entire length of the colon.
WHY IT IS DONE
Colonoscopy is a screening procedure for colon tumors, a type of cancer representing 8.2% of all new tumor cases in the United States.
The American Cancer Society (ACS) recommends that people with average risk for colon tumors start standard screenings at age 45, either with a stool-based test or a colonoscopy.
The ACS recommends that people in good health get screened through age 75; part of that screening process is a colonoscopy every ten years or a virtual colonoscopy or flexible sigmoidoscopy (FSIG) every five years. You should contact your doctor about what is best for you.
Stool-based tests, such as Cologard, are an option for some people. These tests involve the patient obtaining and sending a stool sample to a laboratory.
The model is examined for evidence of DNA and blood cells that have been released by cells that are altered (either pre-cancerous or cancerous).
It can also detect some polyps. A study of 10,000 people ages 50 and up found that the test effectively detected 92#x0025; of cancers. A doctor must prescribe the test.
You may need to have cancer screenings before age 45, or more often than average if you are at heightened risk of colon cancer. Hazards include:
- Having a family history of polyps or colon cancer.
- Having inflammatory bowel disease (Crohn’s disease or ulcerative colitis).
- Being overweight or obese.
- Smoking tobacco.
Research shows that having colonoscopies at the recommended frequency can reduce your risk of dying from colorectal cancer.
Colonoscopy can also diagnose inflammatory bowel diseases such as Crohn’s and ulcerative colitis. And this test can find diverticulosis—pouches in the lining of the intestine.
A colonoscopy can also help diagnose the cause of symptoms such as:
- abdominal pain
- a change in bowel habits, such as diarrhea or constipation
- bleeding from the anus
- unexplained weight loss
HOW TO PREPARE
You may need to quit taking certain medicines a few days before your colonoscopy, especially drugs that increase your bleeding risks, such as aspirin and blood thinners.
Inform your doctor know about all the medicines you take, including ones you bought over-the-counter without a prescription.
One to three days before your procedure, you will need to clean out your bowel so that the doctor may see the inside of your colon.
Your health care provider will give you instructions on how to do this. Generally, you will need to follow a clear liquid diet that includes water, fruit juice, sports drinks, gelatin, and/or broth.
You will also take laxatives as pills that you swallow or powders that you dissolve in clear liquids on the day or so before your procedure.
The laxatives will cause you to have diarrhea, so you will need to stay close to a bathroom. You may also need to use an enema—a liquid inserted into your rectum to help clean it out.
You will have to quit eating and drink the night before or several hours before the procedure.
WHAT TO EXPECT
Colonoscopies are performed at hospitals and outpatient centers. They are usually done by gastroenterologists, doctors who specialize in diagnosing and treating gastrointestinal tract conditions.
First, you will remove your clothes and put on a gown. A nurse or other health care provider will place an IV needle into a vein in your hand or arm to give you pain relievers and possibly a sedative to relax you.
You will most likely remain unaware and pain-free throughout the procedure.
During the colonoscopy, you will lie on your side on a table with your knees drawn up toward your chest.
The doctor will insert a flexible tube known as a colonoscope through your anus into the entire length of your rectum and colon.
Your colon will be filled with air to give the doctor a clearer view of your colon and rectum.
A camera on the end of the scope will send a video image to a monitor so that the doctor can see the inside of your colon.
Nurses and other health care staff will monitor your breathing and other vital signs during the procedure.
The doctor will look for growths called polyps in the lining of your intestine. Polyps are not cancerous, but they can turn into cancer over time.
The doctor will insert instruments up the scope and remove any polyps that are found. If the doctor discovers any abnormal tissue, it will be removed.
Any polyps or pieces of tissue that are removed will be sent to a lab for testing.
The whole procedure should take 30 to 60 minutes. Afterward, you will go to a recovery area to let the anesthesia clear the system.
You may feel cramping, bloating, or have gas from the air placed in your colon during the procedure. This feeling should gradually subside as you pass the gas.
You might experience some mild bleeding from your rectum if the doctor removed any polyps.
You will need somebody to drive you home after the procedure because the sedative will not have completely worn off.
Rest for the rest of the day, if possible. You should eat a normal diet and resume your regular activities on the day after the colonoscopy.
Colonoscopy preparation, anesthesia, and the procedure itself can all cause side effects. The bowel preparation can cause dehydration and electrolyte imbalances.
The medicine used to sedate you and prevent pain can cause allergic reactions. Risks of the colonoscopy procedure include:
- severe pain in your abdomen
- a tear (perforation) in the colon, which may need to be surgically repaired
You may maintain to bleed for up to two weeks after the colonoscopy. See your doctor if the bleeding is severe or have severe belly pain, a fever, or blood in your stools.
Your doctor will assess the results of your colonoscopy with you. It would help if you also discussed when you need to have the test done again.
If you are at average risk for colon cancer and no polyps are found, you should be able to wait 10 years for your next colonoscopy.
If the doctor finds polyps or abnormal tissue, you will need to have the test repeated sooner.
Colonoscopy is the preferred diagnostic tool for high-risk patients. People who are at average risk, however, have some additional options.
Cologuard is the only multi-target stool DNA test (FIT-DNA) approved by the Food and Drug Administration as of 2020.
It involves the patient obtaining and sending a stool sample to a laboratory. The sample is examined for evidence of DNA and blood cells that have been released by cells that are altered (either pre-cancerous or cancerous).
This test can also detect some polyps. A study of 10,000 people ages 50 and up found that the test effectively detected 92#x0025; of cancers, with a 14#x0025; false-positive rate.
A doctor must prescribe the test.
The immunochemical fecal occult blood test (iFOBT), also called the fecal immunochemical test (FIT), is another alternative for patients who are not high-risk.
In this test, the laboratory looks for evidence of blood in a small sample of stool. FIT and iFOBT can be purchased without a prescription; the accuracy rate is 79#x0025; of cancers, with a 5#x0025; false-positive rate.
Another alternative is the PillCam or capsule endoscopy. This procedure uses a tiny wireless camera, which the patient swallows.
As the capsule containing the camera moves through the digestive system, the camera takes pictures, which it transmits to a recorder that the patient wears around the waist.
The images are put together into a color video by computer. This tool is most often used for examining the small intestine, which is difficult to access with traditional endoscopes and diagnosing inflammatory bowel diseases, celiac disease, and cancer.
As with a colonoscopy, this procedure requires the patient to not eat or drink for 12 hours, so the digestive system is clear.
Unlike a colonoscopy, once the pill is swallowed, the patient can go about their daily routine. The capsule will pass in about eight hours.
In all of the less invasive alternatives to colonoscopy, any abnormal findings are followed by a traditional colonoscopy for investigation, polyp removal, or to perform biopsies.
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