A colonoscopy is a procedure used to detect changes or abnormalities in the colon and rectum. The colon, or large intestine, is part of your digestive system. It connects the small intestine to the rectum.
How it works
During a colonoscopy, a long and flexible tube called a colonoscope is inserted through the anus and carefully pushed into the rectum and colon. A tiny video camera at the tip of the tube allows the doctor to view the inside of the entire colon.
This procedure is usually done under sedation for the patient's comfort.
Why do you need a colonoscopy?
Your doctor might recommend a colonoscopy if you have symptoms that suggest potential abnormalities in your colon or rectum.
These symptoms include:
Blood in the stool
Changes in bowel habits such as constipation or diarrhoea
Abnormal weight loss
Screening for cancer
Colonoscopy is also a screening method for colon cancer, colon polyps and inflammatory bowel diseases.
Consider going for a colonoscopy if you:
Are above 45 years old
Have a family history of colon cancer
What are the risks and complications of a colonoscopy?
A colonoscopy is considered to be a safe procedure. Risks such as adverse reaction to the sedative, bleeding from the biopsy site or perforation of the colon or rectum wall are rare. Less than 1% of patients suffer from these complications.
How do you prepare for a colonoscopy?
Your colon needs to be cleared before a colonoscopy. This is to ensure that the colonoscope can capture a clear and unobstructed view of your colon and rectum.
Before your colonoscopy, you will be:
Asked to refrain from solid foods and consume only clear liquids the day before
Placed on an overnight fast
Given a laxative to empty or clear your colon
Your doctor will emphasise and explain the various aspects of bowel preparation. Learn more about preparing your bowels before a colonoscopy.
What can you expect in a colonoscopy?
You will be given a sedative before your colonoscopy. Sometimes, pain medication will also be given to minimise any discomfort.
During the procedure
You will be asked to:
Change into a gown for the procedure.
Lie on your side
The doctor will insert a colonoscope into your rectum. The scope contains a small light and camera at its tip, and a tube to pump small amounts of air or carbon dioxide to inflate the colon and get a better view of the colon lining. The camera sends images to an external monitor so that the doctor can study the inside of your colon.
After the procedure
You may take an hour or so to recover from the effects of the sedative. Do arrange for someone to drive you home after the recovery period.
As the full effects of the sedative may take up to a day to wear off, avoid the following for the rest of the day:
Make any important decisions
Return to work
Consult your doctor if you continue to pass blood or blood clots or if you have persistent abdominal pain or a fever.
Frequently asked questions
A: A colonoscopy is a screening test that is very helpful in diagnosing intestinal problems and detecting colorectal cancer. While there is no specific “end date” to colorectal screening, selective testing may be considered for older adults:
Under 75 years old
You should start regular screenings at age 45 if you do not have:
A family history of colorectal cancer
A personal history of colorectal cancer or certain types of polyps
You should not eat anything solid. You should only consume clear liquids, such as sports drinks, clear juice or broth.
You may drink coffee and tea as long as you do not add any cream. Avoid alcohol and opaque drinks such as milk or orange juice.
You will need to fast for at least 8 hours before the procedure, although sips of water will generally be allowed. For a morning procedure, fasting from midnight is usually sufficient.
As laxatives are necessary to ensure a clean colon, your doctor will prescribe specific laxatives and a schedule for taking these.
A: Yes, you may drink clear liquids such as coffee or tea before a colonoscopy. Other examples of clear liquids include water, broth, pulp-free juice, clear soft drinks or sports drinks and popsicles.
A: As preparations for a colonoscopy are dehydrating, putting fluids and electrolytes back into your system is vital.
You may be advised to:
Drink lots of fluid
Eat soft, easily digestible foods which will not irritate your colon
A: Consult your doctor well ahead of your colonoscopy about any regularly prescribed medications, such as allergy medicine.
Your doctor will decide which ones should be stopped before your procedure.
A: A colonoscopy should not adversely affect your hernias, but do consult with your doctor before your procedure.
A: Complications related to colonoscopies (such as bowel perforation) are rare, but they are more common in the elderly. The prep alone can take a toll on older individuals, especially if they are already frail or ill.
Do consult with your doctor to discuss the pros and cons of undergoing a colonoscopy.
At Mount Elizabeth Hospitals, our colonoscopy patients are in the good hands of our team of gastro specialties and general surgeons who specialise in the full spectrum of gut and digestive system issues.
Our specialists are skilled in the use of minimally-invasive diagnostic tools like endoscopic ultrasound (EUS) as well as advanced surgical techniques that eliminate the need for open surgery.