Purpose: A colonoscopy is recommended in the following cases:

• To find out the possible causes of intestinal symptoms 
• To screen for colon cancer in the case of people who are 50 years or older
• To look for and remove polyps (abnormal growth of tissue on a mucous membrane), which reduces the risk of colon cancer

Symptoms: The following lower gastrointestinal symptoms may indicate the need for a colonoscopy:

• Stomach pain
• Bleeding from rectum
• Chronic or long-term diarrhea
• Chronic or long-term constipation
• Bloody stools
• Black, tarry stools
• Unexplained loss of weight

Cleansing the bowel is needed for a successful colonoscopy. This can be done in the following ways:

1. Changes in diet: Certain dietary changes are recommended the day before the procedure, like eating a light breakfast and lunch and skipping dinner, or consumption of a liquid-only diet.
2. Consumption of only clear liquids: The doctor may recommend drinking only clear liquids, like broth, water, tea or coffee without milk the day before the procedure.
3. Laxatives: The doctor may recommend taking laxatives a day before the procedure, either in liquid or pill form. Sometimes, it may be necessary to take them on the morning of colonoscopy.
4. Enemas: An enema kit may be used the night before or a few hours before the procedure.

• Tell your doctor about any medications that you may be taking, especially if you are suffering from heart problems, high blood pressure, or diabetes.
• Tell the doctor if you are taking any supplements or medications containing iron.
• The doctor may recommend stopping blood-thinning medications like warfarin and aspirin a few days before the procedure. The doctor may also recommend an adjustment in the doses or stopping other medications that you may be taking.

Procedure:

• The procedure is usually performed on an outpatient basis, that is, the patient goes home on the same day of the procedure.
• The patient lies on the left side and the knees are pulled up to the chest during the procedure.
• The procedure is performed under a light sedative, which makes the patient drowsy and relaxed, and a pain-relieving medication.
• In some cases, deeper sedation or anesthesia may be used.
• The doctor gently inserts the colonoscope through the anus into the rectum and colon.
• The image obtained is transmitted onto a video screen.
• The doctor then inserts air or carbon dioxide into the colon to inflate it and give a better view of the intestinal lining.
• The stools and fluids are removed through the colonoscope as required.
• The doctor then slowly and gently pulls out the colonoscope from the colon and rectum and examines it for any abnormalities.
• The doctor may perform other procedures like tissue biopsy (the removal of a sample of abnormal tissue growth and sending it to the laboratory for evaluation) during colonoscopy.
• The procedure takes half an hour to one hour to complete.

The following risks are associated with colonoscopy:

• Allergic reaction to the medications or sedative used
• Bleeding
• Infection
• Dehydration
• Puncture of the large intestine
• Nausea
• Vomiting
• Rectal discomfort

• It takes approximately an hour before the patient begins to recover from the effect of the sedative after colonoscopy.
• It takes up to a day to completely recover from the effect of the sedative.
• Avoid driving or going to work for the day after the procedure.
• If the doctor removes a polyp during colonoscopy, the patient will be advised to eat a special diet temporarily.
• It is normal for the patient to feel bloated or pass gas for some hours after the procedure, as the air from the colon is cleared.
• Walking may help in relieving patient discomfort.
• It is normal to notice a small amount of blood in the first bowel movement following a colonoscopy examination.
• The patient should consult the doctor if he/she continues to pass blood, has a fever, or has abdominal pain.