What is a colonoscopy?
A colonoscope includes a camera, light, and surgical tools to examine the colon.
The digestive system processes and eliminates waste after digestion. The colon and rectum are the final portions of the digestive system and are also referred to as the large bowel or large intestine. A colonoscopy is a diagnostic procedure to evaluate the health of the colon and rectum.
A colonoscopy is done with a colonoscope, a long, flexible tube with a lighted camera at the end of it. The doctor performing the colonoscopy will be able to view the condition of the colon and be able to take samples for biopsy or remove polyps with the colonoscope.
Alternative methods to standard colonoscopy
- Virtual colonoscopy: the colon is filled with air through a rectal tube and high-resolution images are taken with a CT scan.
- Colon capsule endoscopy: The patient swallows a pill-sized capsule with a camera inside that transmits images.
- High-definition colonoscopy: This method comes with improved detection of small polyps.
Drawbacks of virtual colonoscopy and capsule endoscopy
It is not possible to
- remove polyps,
- extract tissue for biopsy, and
- treat bleeding sites.
Why is a colonoscopy performed?
A colonoscopy is performed for the following reasons:
- To screen for colorectal cancer (Colonoscopy is immensely useful in early diagnosis of colorectal cancer.)
To detect the cause for:
- blood in stool
- abdominal pain
- diarrhea or constipation
- changes in bowel habits
- unexplained weight loss
- To detect and remove polyps
- To extract tissue for biopsy if abnormality is found in other tests
- To identify and treat bleeding sites
- To decompress any twist in the colon
When is a colonoscopy performed?
A typical healthy adult should have a colonoscopy at age 50 and continue to have it once every 10 years, more frequently if initially abnormal. People at high risk for cancer should have colonoscopy at an earlier age and more often.
More frequent colonoscopies are also recommended in individuals who:
- have had resection for colon cancer
- have a genetic condition with cancer risk
- have polyposis, an inherited condition with increased risk for polyps
- have inflammatory bowel diseases such as ulcerative colitis or Crohn’s disease
- have close relatives with colon cancer
How do you prepare for a colonoscopy?
The colon has to be completely cleared before a colonoscopy so the doctor is able to view it without any obstruction. The patient must follow a few steps:
- Go on a clear liquid diet one to three days prior, according to the doctor’s advice.
- Avoid red and purple foods like beets, which might lead to misdiagnosis.
- Take an oral laxative mixed in a clear drink the night before and the morning of the procedure.
- Drink large amounts of water to stay hydrated.
- Some may have to use an enema kit to clear the colon.
- Check with the doctor before taking any medications.
- Stop taking blood thinners.
- Inform the doctor if pregnant.
- Inform the doctor of pre-existing conditions, diseases or allergies.
- Inform the doctor if there are any implants.
How is a colonoscopy performed?
Colonoscopy is an outpatient procedure generally performed by a gastroenterologist. The patient receives light sedation and some pain medication. The procedure lasts for thirty to sixty minutes. Some patients might require anesthesia.
It is unsafe to drive or operate machinery for 8 hours post-procedure, depending on anesthesia.
- The patient lies on their side with knees drawn to their chest so the doctor can get a better angle to the colon.
- The doctor will insert the colonoscope through the anus and guide it gently and slowly through the entire colon. The colonoscope is slowly retracted while monitoring for abnormalities.
- The doctor may inflate the colon with air to get a better view.
- The doctor will remove polyps if found, extract tissue for a biopsy, and stop any bleeding.
- The doctor will then gently withdraw the tube.
- The patient should be able to leave in an hour and resume normal activities within a day.
- The results of the colonoscopy help the doctor decide on the future course of treatment.
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How painful is a colonoscopy?
Most people feel nothing more than slight discomfort during the procedure because mild sedation and pain medication are part of the procedure. Some people do not feel much pain even without sedation, but some may experience cramps and pain.
What are the side effects and risks of a colonoscopy?
Colonoscopy is a routine and fairly safe procedure with few side effects and rare complications.
Possible risks and complications: