Colonoscopy is a common diagnostic test that enables the doctor to view the internal parts of the large intestine, particularly the colon. The large intestine is composed of four distinct segments – the cecum that links to the small intestine, the colon, the rectum and the anal canal which leads to the anus. The primary function of the large intestine is to absorb water and salts from undigested food and fluid material and help in the elimination of wastes, toxins from the body.

The colonoscopy protocol is usually performed by the doctor when the patient reports stomach aches along with prominent signs of gastrointestinal discomfort such as bleeding, aberrant bowel movements including frequency, colour and consistency of stools, pain in the abdomen. Its main use is in detecting any abnormal growths such as polyps in the colon, rectum or to look for indications of colon cancer like odd lumps, tumour masses.

Also Read: Colon Cancer: Causes, Symptoms And Treatment

Why It Is Done:

The doctor generally advises the patient to undergo a colonoscopy for the following reasons:

Determine The Nature Of Intestinal Problems: Such as what are all the most likely causes of symptoms like experiencing abdominal pain often, bleeding from the rectum or while passing stools like in anal fissures, haemorrhoids, incessant diarrhoea, uncontrolled constipation or any severe infection/inflammation in the gut.

Also Read: Constipation: Causes, Symptoms And Treatment

Establish Evidence Of Colon Cancer: In case of typical symptoms of tumour growths in the large intestine or if the individual is predisposed to colon cancer owing to family history, old age, other risk factors.

Identify And Remove Polyps: If the individual has had a prior instance of colon polyps and the atypical growths in the intestinal lining keep recurring, a colonoscopy is done to spot their location and remove them to reduce the risk of the lumps turning into colon cancer.


The procedure for a colonoscopy is invasive and entails inserting an instrument known as a colonoscope or sometimes just scope via the rectum into the colon. A camera is affixed to the tip at the farther end which captures images of the interior areas of the colon and helps in diagnosing the health concerns plaguing the gastrointestinal tract.

Before the procedure, the patient is given a list of instructions to be followed to fully prepare for the colonoscopy. These comprise consuming a liquid diet with no solid foods, creamy milk, aerated drinks. Moreover, the physician advises the individual to take a laxative or enema kit to empty the colon prior to the test and also stop all medications for diabetes, hypertension, blood-thinning drugs, iron supplements, medicines for stroke for at least one week before the colonoscopy.

The colonoscopy procedure is performed in a hospital or clinic by a specialist doctor/gastroenterologist or trained nurse. The patient is requested to wear a long, loose hospital gown. To minimise the pain felt while inserting the colonoscope, the doctor injects a sedative intravenously along with an analgesic which makes the patient a bit drowsy. The patient is then asked to lie down on the left side, raising their knees close to the chest. First, some air is dispersed to widen the opening of the colon, then the colonoscope is inserted to explore the inner regions of the large intestine, lining of the gut walls and record detailed images. The entire process usually takes about 30 minutes, with 12 minutes to push the flexible apparatus for a distance of 5 - 6 feet into the colon and another 12 minutes to fully withdraw it from the body. Sometimes, polyps are identified and if they need to be removed at once, then the process lasts for a longer duration.

After the colonoscopy, the patient requires to rest for a day or two for the pain to subside and to fully regain bowel movement and hence must avoid driving, going to work or undertaking intense activities at home in that period.
Colonoscopy Procedure


A colonoscopy is an invasive, slightly painful procedure but generally does not lead to any serious complications. In rare situations, the risks associated with this diagnostic protocol include:

  • Adverse reactions to anaesthesia or the medications injected as part of the sedative via the veins, which result in waking up feeling rather shaky and unstable
  • Bleeding from the rectum or blood in the stool post the procedure
  • Damage or tearing of the walls in the colon or rectum due to undue pressure, force applied during the scan, which may require surgery to mend the injured tissues


After the images captured from the colonoscope are thoroughly analysed by the doctor, the patient is told to schedule an appointment with the healthcare provider to discuss the results.

A negative result in a colonoscopy implies that no irregularities were identified from the scans of the internal segments of the colon, rectum. In case the patient is above the age of 50 or has a family history of colon cancer, previous medical history of polyps, other genetic gastrointestinal ailments, then depending on the level of risk, the medical expert recommends taking a colonoscopy in either 1 year, 5 years or 10 years.

A colonoscopy provides a positive result if polyps or tumour growths are spotted in the linings, walls or internal tissues of the colon, rectum. The physician ascertains the size, number and nature of polyp growths and advises the patient on whether they need to be removed to decrease the chances of colon cancer or are harmless, benign masses that do not need any further treatment.