For most people, the hardest part of a colonoscopy is not the test itself. It is the bowel preparation the day before. Knowing exactly what to expect makes both parts much easier, and a good preparation makes the test safer and more accurate.
Imagine receiving a letter for a colonoscopy after a positive bowel screening test. Your mind races to cancer, you dread the prep you have heard horror stories about, and you are not sure whether you will be awake. A week later it is over, and the main thing you remember is how much you enjoyed your first meal afterwards.
What a colonoscopy is
A colonoscopy is a test that looks at the inside of your large bowel (colon and rectum) using a long, thin, flexible tube with a tiny camera on the end, called a colonoscope. The tube is passed gently through the bottom and guided around the bowel while images appear on a screen.,During the test, the endoscopist can take small samples (biopsies) and remove growths called polyps. Removing polyps is one of the most effective ways to prevent bowel cancer, because most bowel cancers develop slowly from polyps over many years.
Why it might be recommended
- A positive bowel screening test, such as a FIT test
- Blood in your poo or rectal bleeding
- A lasting change in bowel habit, such as looser stools or constipation
- Unexplained iron deficiency anaemia
- Unexplained weight loss or ongoing tummy pain
- Monitoring inflammatory bowel disease or a history of polyps
- A strong family history of bowel cancer
Preparing in the days before
Your hospital will send detailed instructions, and it is important to follow them exactly, because they can differ between centres. Many people are asked to switch to a low-fibre diet two or three days before, avoiding seeds, nuts, wholegrains, raw vegetables and fruit skins. White bread, white rice, plain pasta, eggs, chicken and fish are usually fine.,Tell the team in advance if you take iron tablets, blood thinners, diabetes medicines or medicines for constipation, as some may need to be stopped or adjusted. Never stop a blood thinner unless you have been told to.
Getting through bowel prep
Bowel preparation is a strong laxative drink that empties the bowel so the camera can see clearly. You will usually take it in one or two doses, often the evening before and the morning of the test. Expect frequent, urgent, watery bowel movements within a few hours.,Practical tips help: chill the drink, drink it through a straw, follow each glass with a clear drink you like, stay near a toilet, use soft toilet paper or wipes and a barrier cream to protect sore skin, and keep drinking clear fluids to avoid dehydration. Your stool should eventually look like clear or pale yellow liquid. If it does not, tell the unit, as the bowel may not be clean enough.
Sedation and comfort
Most people are offered sedation, pain relief or a gas and air mixture, depending on the country and hospital. With sedation, you are usually relaxed and drowsy but not fully asleep, and many people remember little of the test. In some places, deeper sedation is given by an anaesthesia team. If you have sedation, you will need someone to take you home and stay with you, and you should not drive, work or sign important documents for 24 hours.
What happens during the test
You will change into a gown and lie on your left side with your knees bent. After sedation, the colonoscope is gently inserted and air or carbon dioxide is used to open the bowel so it can be seen. This can cause cramping or a feeling of needing to pass wind, which is normal.,The test usually takes 20 to 45 minutes. The team may ask you to change position or press on your tummy to help the scope move around bends. If anything is painful, tell them; they can adjust the scope or give more pain relief.
Risks
Colonoscopy is very safe, but like any procedure it carries small risks. These include bleeding, especially after polyp removal, a reaction to sedation, and, rarely, a tear in the bowel wall (perforation), which may need surgery. Serious complications are uncommon. Seek urgent help if you develop severe tummy pain, a swollen hard tummy, fever, vomiting or heavy bleeding after the test.
After the test and getting your results
You will rest for a short time while the sedation wears off. Bloating and passing wind are common for a few hours. Most people can eat and drink normally once they are awake.,The team will often tell you what they saw before you leave. Results of biopsies or removed polyps usually take a few weeks. Depending on what is found, you may need no further tests, a repeat colonoscopy in a few years, or referral to a specialist team.
Alternatives to colonoscopy
Colonoscopy is the most complete test of the large bowel, but it is not the only one. A flexible sigmoidoscopy looks at the lower part of the bowel only and needs less preparation. CT colonography, sometimes called a virtual colonoscopy, uses a CT scan after bowel preparation to create images of the bowel. Stool tests such as FIT are used for screening.
Each option has advantages and limits. For example, if a CT colonography finds a polyp, you will usually still need a colonoscopy to remove it. Your healthcare provider will recommend the test that best fits your symptoms and health.
Frequently asked questions
Will I be awake?
It depends on the sedation used. Many people are drowsy and relaxed, and some are deeply sedated.
Is it painful?
Most people feel some cramping or pressure, which sedation and pain relief help with.
Can I take my usual medicines?
Usually yes, but follow your instructions about iron, blood thinners and diabetes medicines.
What if I cannot finish the prep?
Call the endoscopy unit for advice. A poorly prepared bowel may mean the test has to be repeated.
But what if they find cancer?
Most colonoscopies do not find cancer. Many find nothing serious or only small polyps, which are removed during the test. If cancer is found, finding it early gives the best chance of successful treatment.
Your next step: If you have been invited for a colonoscopy, read your prep instructions today and buy your clear fluids and soft wipes in advance.
Related: Bowel cancer signs
Sources: NHS, Bowel Cancer UK, American Society for Gastrointestinal Endoscopy, US National Institute of Diabetes and Digestive and Kidney Diseases.
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