Your colonoscopy/ gastroscopy

What is a colonoscopy/ gastroscopy?

Colonoscopy and gastroscopy are commonly performed procedures used to examine the upper and lower gastrointestinal tract.

Colonoscopes/ gastroscopes are long flexible fibre-optic instruments with a small lens on the tip. In colonoscopy, the colonoscope is passed through the anus and guided around the colon. In gastroscopy, a gastroscope is passed through the mouth, oesophagus and stomach into the first part of the small bowel.

They provide excellent viewing of the inner lining of the gastrointestinal tract and are useful to exclude serious upper and lower gastrointestinal issues such as polyps, cancer and inflammatory conditions. Any abnormalities may be biopsied and/or removed.


There are several indications for investigation with colonoscopy and/ or gastroscopy. Your General Practitioner and/ or your specialist will advise you on the need for these investigative procedures.

Patients with a family history of bowel cancer, or a personal history of inflammatory bowel disease or polyps, may require regular screening with colonoscopy. Any patient with symptoms such as a persisting alteration in bowel function, rectal bleeding or anaemia should be seen by a doctor to assess the need for colonoscopy. Those with a positive bowel screening stool test should also be considered for colonoscopy.

Preparing your bowel for colonoscopy

Colonoscopy requires bowel preparation to allow visualisation of the inner lining of the bowel. This involves a clear liquid diet and drinking a laxative solution in the 24 hours prior to your procedure.

You will be required to purchase the bowel preparation (laxative solution) from your pharmacy, and instructions on how to prepare your bowel are outlined in the link below. Admission and fasting times are also provided at the time of booking .

Click here for Bowel Preparation Instructions

What does the procedure involve?

The procedure is usually performed as a day surgery procedure in a Day Procedure unit. The procedure is performed under sedation or anaesthesia with an anaesthetist present. The test itself takes about twenty to thirty minutes to perform.

You will need someone to drive you home after the procedure and you will not be able to work or drive until the following day.  Dr Kozman will speak to you at the completion of the procedure and a written report will be provided. 

If any abnormality is noted at colonoscopy it may be possible to biopsy or remove this at the time. Any tissue that is removed will be sent to the pathologist and analysed. It may take up to seventy-two hours to get pathology results.

What are the risks?

Colonoscopy is a safe procedure but is associated with small risks. These include adverse reactions to the bowel preparation, such as dizziness and dehydration, and complications relating to the anaesthetic/ sedative medication administered during the procedure.

If biopsies are taken or polyps are removed there is a small chance of bleeding which may occur up to 1-2 weeks after the procedure. The most significant and serious risk of colonoscopy is colonic perforation. Up to 1 in a 2000 patients undergoing diagnostic colonoscopy may suffer perforation of the colon where a hole is made in the bowel wall allowing gas or faecal material into the abdominal cavity. This may require admission to hospital, antibiotic treatment, and in some circumstances, even major bowel surgery.

Colonoscopy is an extremely accurate test but small polyps may not be seen. The risk of missing a significant polyp or cancer is extremely small, and may be dependent on the quality of the bowel preparation.

More information regarding colonoscopy and gastroscopy can be found under the Treatments menu of this website, or by clicking the following links:

Virtual Colonoscopy

This is a radiological method of assessing the colon. It can be an alternative to colonoscopy in some specific situations. It still requires preparation of the bowel. A CT scan is performed after insufflation of air into the colon through the anus. Abnormal findings usually require further investigation with conventional colonoscopy (as outline above).