A colonoscopy is the gold standard screening test for colorectal cancer. It allows a doctor to examine the entire length of the colon and rectum using a colonoscope, which is a thin flexible tube with a camera at the end. During a colonoscopy, any abnormal growths or polyps can be removed before they become cancerous. That’s why experts recommend colonoscopies starting at age 45 for average-risk adults. The thought of having this invasive test makes many people uncomfortable, though. Are there alternatives to getting a colonoscopy?
What is a colonoscopy?
A colonoscopy is an outpatient procedure performed by a gastroenterologist. Patients are given sedation and pain medication intravenously before the test starts. Then the doctor inserts a lubricated colonoscope into the rectum and guides it through the entire colon. The scope has a light and camera that allows the doctor to view the colon lining in real time on a video monitor. If any polyps or other abnormalities are found, the doctor can remove them right away using tools passed through a channel in the colonoscope. The tissue samples (biopsies) can then be sent to a lab for analysis.
The procedure itself usually takes 30-60 minutes. You will need to take the rest of the day off work or other activities to recover from the sedation medications. You’ll also need someone else to drive you home after the colonoscopy since you won’t be allowed to drive for the remainder of the day.
Why get a colonoscopy?
Colonoscopies allow doctors to screen for colorectal cancer and remove polyps before they turn into cancer. Colorectal cancer is the second leading cause of cancer deaths when men and women are combined. The American Cancer Society recommends colon cancer screening for average-risk adults starting at age 45. Those with risk factors like a family history may need to start sooner.
Screening is important because colorectal cancer doesn’t always cause symptoms right away. Catching it early vastly improves survival rates. During a colonoscopy, a doctor can find and remove precancerous polyps. Removing these polyps can prevent cancer from developing. Colonoscopies are the most sensitive test, meaning they are the best way to find all polyps and early cancers.
What are the risks of a colonoscopy?
Colonoscopies are generally very safe when performed by a highly trained doctor. Complications are rare but can include:
- Bleeding from biopsy site or polyp removal – Usually minor and stops on its own
- Perforation or tear in the colon wall – Rare, may require surgery to repair
- Infection
- Adverse reaction to sedative medications
There are some risks with the colonoscopy prep too. Taking strong laxatives can cause diarrhea, nausea, vomiting, bloating, and electrolyte disturbances. Dehydration can occur if you don’t drink enough clear liquids before and after taking the bowel prep solution.
What are alternatives to a colonoscopy?
While a colonoscopy is still the “gold standard” for detecting colon polyps and cancer, other screening tests are available. Some options include:
CT colonography
Also known as a virtual colonoscopy, this test uses CT scans to take images of the colon. No scope is inserted into the rectum. A small flexible tube is inserted briefly to inflate the colon with air or carbon dioxide. Patients will still need to do bowel prep. This test can detect larger polyps but may miss smaller ones. If an abnormality is found, a regular colonoscopy is usually still needed to remove polyps or biopsy the area.
FIT – Fecal immunochemical test
This stool-based test detects hidden blood in feces, which can be a sign of cancer or polyps. It’s done annually at home using a kit containing a small brush to obtain a fecal sample. The sample is sent to a lab. If results are positive, a colonoscopy will be needed to investigate further. This test only detects bleeding polyps and cancers, not precancerous polyps.
Cologuard
This is another noninvasive stool test that is done every 3 years. It detects blood as well as certain DNA mutations associated with colon cancer. Users collect an entire bowel movement and ship it to the lab. False positives are possible which would require a follow-up colonoscopy. Not all precancerous polyps bleed or contain DNA mutations, so this test may miss some.
Flexible sigmoidoscopy
During this test, a short flexible scope is inserted into the rectum and lower third of the colon. Abnormalities can be biopsied or removed. It does not examine as much of the colon as a colonoscopy, so it may miss issues higher up. If polyps or cancer are detected, a full colonoscopy will be needed. Flexible sigmoidoscopies are recommended every 5 years along with other tests like FIT annually.
Capsule endoscopy (PillCam)
Patients swallow a small capsule containing a camera that records images as it passes through the GI tract. Captured images are transmitted to a recorder worn on a belt. This is mainly used for parts of the small intestine hard to reach by scope. It has limited use for colon screening and mainly detects bleeding. Patients must do bowel prep, and there is a risk capsule could get stuck requiring surgery.
When is a colonoscopy still recommended?
While the alternatives above can screen for colon cancer for most average-risk patients, there are some instances where a colonoscopy may still be the best option:
- If polyps or cancer are detected on any other screening test
- If you have colon cancer symptoms like bleeding, changes in stool, abdominal pain
- If you have a higher risk of colon cancer due to family history, inflammatory bowel disease, previous polyps or colon cancer
- As a one-time screening if you have never been screened before age 45
- Every 10 years after a normal screening colonoscopy
Talk to your doctor about when colonoscopy versus other screening tests for colon cancer are appropriate for your individual situation.
What are the pros and cons of colonoscopy alternatives?
| Screening Test | Pros | Cons |
|---|---|---|
| CT colonography | Less invasive, no sedation needed | Still requires bowel prep, May miss smaller polyps, Additional colonoscopy often still needed |
| FIT | Simple, no prep, done at home annually | Only detects bleeding, misses precancerous polyps |
| Cologuard | Done at home every 3 years | May miss polyps, False positives require colonoscopy |
| Flexible sigmoidoscopy | Quick procedure, examines lower third of colon | Misses right side of colon, Limited view, Colonoscopy still needed if abnormalities found |
| Capsule endoscopy | No prep or sedation | Risk of capsule getting stuck, Limited view, mainly checks for bleeding |
Conclusion
While alternatives to colonoscopy are available, they each have limitations. Stool tests must be done more frequently but only detect bleeding and some mutations. Other scope tests don’t examine the entire colon. Radiology tests like CT colonography still require prep and may miss small polyps. The choice between colonoscopy and other screening tests depends on your personal risk, preferences, and how well you can tolerate certain tests. Talk to your doctor to determine the best colon cancer screening plan for you.