Colonoscopy – the best method for early detection of malignant colon diseases

Author: Assoc. Prof. Dimo Kurktschiev

What is a colonoscopy?

Colonoscopy is an endoscopic method for diagnosing and performing therapeutic procedures of the colon and part of the small intestine. A colonoscope is a thin, long, flexible instrument with diameter circa 10-12 mm which has a light and camera at one end and it is inserted into the anus of the patient. This medical procedure is performed on an outpatient’s basis by a specialist in gastroenterology. An endoscopy nurse, trained to work with an endoscopic apparatus, will assist the doctor with the procedure


What is a colonoscope?

The colonoscope consists of an easily flexing tube that is inserted through the patient’s anus. The tip of the tube can be moved in all directions and has openings for light, camera and various tools. At the other end of the colonoscope is located the control head by which the movements of the apparatus are controlled. A cable system delivers the image from the inside of the colon to a video screen. Through the colonoscope, the doctor can obtain biopsies (small pieces of tissue which are examined under a microscope), to remove polyps and small tumours, to stop bleeding, to expand narrow sections.

What happens during the colonoscopy?

The colonoscopy is performed in a specially equipped medical office and it lasts about 10-15 minutes. During the procedure the patient is in the supine left lateral position. The procedure starts by placing the tip of the apparatus in the anus and gradually advancing to the other end of the large intestine – the cecum, while all its parts are examined. In some cases, it is possible to examine a short segment of the small intestine as well. During the colonoscopy, the patient may feel bloated with mild abdominal pain for short time which is usually tolerable.

During the colonoscopy, the doctor monitors on the video screen the inside of the large intestine, looking for changes in its structure. With the help of the colonoscope not only becomes accessible to view the lining of the large intestine along its entire length, but different tools also can be inserted into the channels of the apparatus for the purpose of the coagulation, biopsy, polypectomy etc.

It is possible during the procedure the specialist to find areas that require more detailed inspection, and then it is necessary to obtain biopsies using an endoscopic clip or brush, inserted through the instrument's channel. When polyps, severely inflamed areas of the lining or tumour formation are detected, 5 or more biopsies must be obtained. This is not associated with extra pain or unpleasant sensation.

Normal image of the colon in a colonoscopy

Benign polyp (adenoma) of the large intestine

Cancer of the colon seen in a colonoscopy

Is anesthesia needed for colonoscopy?

At the discretion of the physician, an intra-muscle or intravenous injection of sedative drugs can be given (sedation). Sedation is a condition in which the patient is conscious, but the sensation of pain and discomfort is highly reduced. It is achieved by drugs other than those used for general anaesthesia. In state of sedation it is possible to have contact with the patient and he or she can follow the instructions of the physician. Typically the patients have no memory of the procedure, despite of the consciousness. After the colonoscopy when the sedation has been used, the patient will not be able to drive, therefore it is desirable to provide a companion to take him home.

In some cases, especially at patient’s request (rejection of any “chemical intervention”) or in case of intolerance to the relevant medications, the colonoscopy can be performed without any anesthetics or sedation. In rare cases in patients with anxiety, general anesthesia will be required, which is associated with additional risk and inconvenience. Upon prior consultation with the physician, will be discussed the sedation options and which method will be the best choice in the specific case.

When is colonoscopy necessary?

Diagnostic colonoscopy is most often needed to clarify the cause of certain complaints such as abdominal pain, bloating and discomfort, unexplained diarrhea, alternation of constipation with diarrhea, blood in stools, established laboratory anemia.

Control colonoscopy is performed after already removed polyps and /or tumors.

Preventive colonoscopy in many countries is used as a screening method. The goal is early detection and removal of polyps before their transformation into a malignant tumor.

A therapeutic colonoscopy is used in the following manipulations:

• Removal of polyps and small tumours
• A colonic dilation

Preparation before colonoscopy:

The colonoscopy is performed on an empty stomach. Patients are instructed not to eat and drink large amount of liquids 8 hours before the investigation. The medical office will provide the patient with detailed information on how to prepare for the procedure the day before it. It involves taking a laxative and drinking sufficient amount of water. The cleansing is combined with stopping food intake until the colonoscopy is completed. Proper bowel preparation is extremely important. Poor bowel preparation could be the reason for polyps and tumors being missed. There can't be achieved adequate examination of the colon in the presence of rinsing water and food residues.

Preparation before colonoscopy (laxatives and stopping food intake)

Possible risks and complications of colonoscopy:

A very small percentage of patients could experience injuries of the wall of the colon with perforation and/or haemorrhage after biopsy or polypectomy. After the procedure the patient may feel bloating, abdominal discomfort and increase of gas passing (this is because air is being introduced into the colon during the colonoscopy) and these complaints go completely without additional therapy.