What is a colonoscopy?

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.
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

QUESTION
What are risk factors for developing colon cancer? See AnswerHow 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.
Procedure
- 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.
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:
- Perforation of the colon
- Persistent rectal bleeding
- Infection and fever
- Abdominal distension
- Abdominal pain
- Rupture of the spleen
- Small-bowel obstruction in patients with adhesions
- Allergic reaction to medication
Top How Painful Is a Colonoscopy Related Articles
10 Natural Remedies for Colon Cleansing
A colon cleanse is the act of flushing out or cleaning the large intestine. They may be performed by professionals called colonic hygienists. In spite of insufficient research to support its benefits, the goal of colon cleansing is to clear the colon of any stagnant, supposedly toxic waste encrusted on the walls of the large intestine.Colon Cancer (Colorectal Cancer)
Colon Cancer (Colorectal Cancer) is a malignancy that arises from the inner lining of the colon. Most, if not all, of these cancers, develop from colonic polyps. Removal of these precancerous polyps can prevent colon cancer.Colon Cancer: How Your Food and Diet Can Affect Colorectal Cancer Health
Diet, including nutrient, antioxidant, and vitamin intake, affects colon cancer risk. Certain dietary factors either decrease or increase the risk of colorectal cancer, breast cancer, and other diseases. Dietary factors may either inhibit or stimulate the development of cancer cells. Have a nutrition plan that decreases the risk.Colon Cancer Illustrations
Most, if not all, of these cancers develop from colonic polyps. Removal of these precancerous polyps can prevent colon cancer. See a picture of Colon Cancer and learn more about the health topic.Colon Polyps
Colon polyps are fleshy growths inside the colon lining that may become cancerous. Symptoms include rectal bleeding. Learn about causes, signs, treatment, and how to prevent colon cancer.Colonoscopy Procedure and Preparation
A colonoscopy is a procedure whereby a docotor inserts a viewing tube (colonoscope) into the rectum for the purpose of inspecting the colon. Colonoscopy is the best method currently available to diagnose, detect, and treat abnormalities within the colon.Colorectal (Colon) Cancer Quiz
What is colorectal (colon) cancer and who gets it? Take this quiz to find out how this disease may be prevented.Colon Cancer Slideshow
Colorectal cancer (colon cancer) is the cause of many cancer deaths. Learn about the warning signs, symptoms, screening process, stages, and treatment related to colorectal cancer.Does a Right Hemicolectomy Remove the Appendix?
A hemicolectomy is done if the part of the colon that has been infected, damaged or riddled with colon cancer beyond repair. In case of severe appendicitis or in cancer of the appendix, the surgeon will also cut the appendix along with the right colon and connect what's left of your colon to your small intestine.Can I Eat Mashed Potatoes 2 Days Before Colonoscopy?
Colonoscopy is a procedure used to detect abnormalities in the large intestine (colon). One day before the procedure, it is advised not to eat any solid or semi-solid food, such as mashed potatoes, applesauce, oatmeal, etc. A clear liquid diet must be taken 24 to 72 hours before the procedure.Endoscopy vs. Colonoscopy
Both endoscopy and colonoscopy are nonsurgical procedures that involve use of a flexible tube with a light and camera to examine parts of the digestive tract. A colonoscopy is a type of endoscopy.How Long Before a Colonoscopy Should I Stop Drinking Water?
A colonoscopy is a test to look at the inside of the colon. Usually, doctors recommend patients undergoing a colonoscopy to stop drinking clear liquid or water at least three to four hours before the procedure. However, patients with diabetes and who are dehydrated may take a few sips of water after consulting their doctor.Is A Colon Resection A Major Surgery?
Colon resection (colectomy) is the surgical removal of part or the entire colon. Colectomy is a major surgery and may take up to four hours for completion. Colectomy is performed under general anesthesia and may require hospitalization for up to a week or more.All About Polyps
Do you know what a polyp is? Learn the definition of a polyp, which can be found in the sinuses, stomach, colon, gallbladder, and elsewhere. Learn about endometrial polyps, adenomatous polyps, sessile polyps, pedunculated polyps, uterine polyps, and cervical polyps. Some are more likely to cause cancer.What Is the Difference Between EMR and ESD?
The main endoscopic techniques that are available for the removal of colon (part of the large intestine) polyps or cancer include endoscopic mucosal resection (EMR), endoscopic submucosal dissection (ESD), and polypectomy. Resection removes a part of an organ or a structure. Dissection cuts apart or separates tissue for further study or diagnosis.