What is Colonoscopy?

Colonoscopy is a procedure that uses a colonoscope, which is a long flexible tubular instrument with a light source, inserted via the anus, to assess the lining of the colon or the large intestine so we can examine for any abnormalities. 

It is done as a Day Surgery procedure, which takes about 20-30 minutes approximately. It is done under moderate sedation, which means that the patient will be given medications into the vein to make them feel relaxed, painless, and drowsy.

During the scope, air is blown into the colon and helps us to see more clearly, which may cause mild abdominal discomfort but will resolve. We will examine the colon as the scope is slowly withdrawn and will do procedures (which may include biopsy or polypectomy) as required depending on what we find.

What are the most common reasons for this procedure?

  • Screening for colon cancer
    • Age 50 and above
    • Family history of colon cancer
    • Family history of bowel cancer
    • Family history of other high-risk cancers
  • Surveillance after cancer surgery
  • Surveillance of colon polyps
  • Occult blood in stools or positive FOBT (Fecal Occult Blood Test) or FIT (Fecal Immunochemical Test) results
  • Loss of weight
  • Loss of appetite
  • Change in bowel habits
    • Diarrhea
    • Constipation
  • Blood in stools or bleeding per rectum
  • Abdominal pain or discomfort

What should the patient do before the procedure?

The patient should fast overnight, prior to the procedure. They should also avoid high-fiber diet for three days before the scope.

We will prescribe the patient some laxatives (to be taken the night before the colonoscopy) and provide instructions on how to take the prescribed laxatives. Such laxatives will result in diarrhoea, which will clean out the entire intestine.

It is important that the patient follows these instructions since a dirty colon will be difficult to assess, and small lesions can be missed. We will teach the patient to assess if the bowel preparation is adequate enough for a good assessment during colonoscopy.

Meanwhile, please inform us about any specific medical conditions the patient has (e.g. diabetes, hypertension, heart valves, blood thinner medications, etc.), since that will require more special instructions.

What should the patient do after the procedure?

Immediately after the scope, we will observe the patient in the recovery room and monitor them closely. If certain procedures were done during the scope, then certain medications have to be held off temporarily – which we will clearly instruct before discharging the patient.

If biopsy or polypectomy were done, then the histology/results of the same will have to be traced at the next clinic visit.

Patients may feel some cramping or bloatedness, which will resolve quickly once they start passing gas.

We will recommend that the patients arrange for a family member or a driver to bring them back home after the scope, since it is unsafe to drive or operate any machinery for about 8-12 hours after the procedure due to the sedation medication given during the procedure. However, if the procedure is done under local anesthesia, the patient can go home alone on their own. Patients can also resume a normal diet after waking up.

Are there complications that might arise from this procedure?

Some patients might experience abdominal cramps or bleeding, especially when biopsy or polypectomy is done. A very small number of patients might also experience perforation of the bowel.

However, the incidence of the above complications is very low – about one in 1,000 to 1,500 – and if it happens, then the patient may require emergency surgery. While it may be catastrophic, the procedure is overall considered to be safe in experienced hands.

Do note that in about 2-3% of the patients, it may be technically difficult to complete the scope due to anatomical reasons and/or poor bowel preparation. For such patients, we may have to arrange for alternative imaging techniques, such as CT Colonography. They can also opt to repeat the scope another day.

What should the patient expect a few days after the procedure?

During the patient’s next clinic visit, we will provide them with scope pictures taken during the procedure, as well as some histology report, and proceed with further management. Depending on the findings, we might also recommend follow-up scopes in specified intervals.

Written by Dr Natarajan Suresh Khanna