What is a colonoscopy?

Pronounced “koe-lun-OS-kuh-pee”, a colonoscopy is a test, exam or procedure (the terms are used interchangeably), that is able to detect any abnormalities or changes in the colon (large intestine) and the rectum.

The doctor performing a colonoscopy usually a specialist known as a gastroenterologist, is able to evaluate and examine the inside or inner lining of the large bowel also known as the large intestine, using a long and flexible tube that is about as thick as the average sized finger and has a camera and a light at the tip of it. This tube is known as a colonoscope. If it is necessary, any types of abnormal tissues that are found during the procedure will be removed through this scope. As well as this, biopsies, which are tissue samples, may be taken and sent to a lab for various kinds of testing.

Colonoscopies help to detect anything that may be wrong inside of the colon.

The procedure can help find colon polyps (abnormal growths), tumours, bleeding, inflammation and ulcers. A colonoscopy can also be utilised as a screening test in order to check if there are cancer cells present or any precancerous growths, in the form of polyps, in the rectum or colon. 

In order to conduct a colonoscopy, the small tip of the colonoscope is first inserted in through the anus, and then will slowly advance with the guided, visual control of the doctor (imagery provided by the camera at the end of the scope is projected onto a monitor, allowing the doctor to see what he/she is doing) and pass through the rectum and finally the colon. It will normally only go as far as the first part of the colon, this is known as the caecum. 

The colonoscope tube is thin and flexible and ranges from 125 centimetres (48 inches) to 183 centimetres (72 inches) in length. The doctor is able to take pictures and record the entire procedure thanks to the camera at the end of the scope. There is also a test known as a sigmoidoscopy, this is a test that shows only the lower part of the colon and the rectum. The lower colon is referred to as the sigmoid. This test normally uses a smaller scope.

Before a colonoscopy, you will be asked to prep your colon, which means you will have to empty and clear the bowel of faeces. This will normally take place about one to two days before the procedure, depending on the type of colon prep your doctor recommends. Some preps are even able to be done the night before the colonoscopy.

Bowel prep (or the thought of it) can be an uncomfortable experience for a lot of people, with many patients noting that the colon prep was worse for them than the actual colonoscopy procedure. Still, it is nothing more than a day of slight discomfort that will ultimately benefit you health wise.

The prep involves both dietary changes and the administration of laxatives a day or two prior to the procedure.  The recommended dietary changes can often leave you feeling hungry as they usually mean cutting back on heavy foods two days before the procedure and the day before often consists of just a clear liquid diet.

They day before the procedure, laxatives used for bowel prep will be prescribed.  It is best to stay home at this stage as you will need to have frequent bowel movements. A colon prep will cause frequent and loose stools, as well as diarrhoea in order to empty out your colon for the procedure.

A colonoscopy can be a daunting procedure for a lot of people. In order to put your mind at ease, it is advised that you read the following article as it will cover everything about the procedure in detail, from the preparation to what you can expect on the day, the actual test, results and answer any more questions you may have.

Doctor holding an endoscope

What is my colon?

The colon is also known as the large intestine (large bowel) and forms the lowest part of the gastrointestinal tract. It is attached to the anus through the rectum, the anus is the opening of the body where your faeces is excreted.

The colon is a coiled and tube-like shape and is responsible for removing water from food that is digested. The material that remains from the food, which is known as stool, is moved through the colon and into the rectum and finally out of the body through the anus.

The last portion of the small intestine, known as the ileum, is connected to the first portion of the colon, known as the caecum, found in the lower right abdomen. The short curving area of the colon is known as the sigmoid colon and is located just before the rectum.

What is the difference between the various types of endoscopes?

An endoscope is the name for a common medical device that has a light source at the end of it to help the doctor to visualise a certain cavity or organ of the body. In the situation where it is used as a tool to visualise the early portion of the intestine and the stomach, it is referred to as an upper GI endoscope. In recent times, doctors prefer to replace the term upper GI endoscope with simply, endoscope, referring to the procedure as an endoscopy.

If an endoscope is used to visualise the tubes of the lungs, it is called a bronchoscope. When it is used to visualise the throat, it is called a laryngoscope. When used for the abdomen, is it known as a laparoscope, and for the uterus, it is known as a hysteroscope. When an endoscope is used for a colonoscopy, is it called a colonoscope.


Why do I need a colonoscopy?

A colonoscopy may be recommended by your doctor for the following reasons:

  • To investigate and monitor intestinal symptoms and signs – A colonoscopy will help your doctor to explore any possible causes of unexplained abdominal pain, chronic constipation, chronic diarrhoea, iron deficiency anaemia, weight loss and irritable bowel syndrome (IBS), or check the colon when abnormal results have been shown after an MRI, CT scan, stool test, barium enema or virtual colonoscopy (an X-ray version of a colonoscopy).
  • To screen for colon cancer – If you are over the age of 50 years old and have an average risk of developing colon cancer, which means you do not have any additional risks of cancer besides your age factor, then your doctor may suggest that you have a colonoscopy every 10 years or so in order to screen for cancer. There are other options that can be used to screen for colon cancer, however, it is best to speak to your doctor regarding what is available to you.
  • To check for more colon polyps - If your doctor has found any polyps in your colon in the past, then he or she may suggest that you have a follow-up colonoscopy to detect and remove any new polyps that may develop in future. This helps to reduce your risk of developing colon cancer.

What are polyps?

Polyps are tissues growths that are abnormal and will often appear as mushroom-like stalks or small and flat bumps. Many polyps are less than half an inch in size, which is 1.2 centimetres. Polyps that are found in the colon or rectum tend to be the most common, however, polyps can also form in the sinuses, cervix or ear canal.

Polyps in the colon will normally occur in the lining of the large intestine and protrude out into it. Polyps are a clump of cells, and most of them are harmless, however, over time, these polyps may develop into cancer of the colon which can be dangerous and often fatal if found in the later stages of cell development. In most cases, colon polyps do not cause issues and remain undetected for a person’s entire life.

 Polyp removal

What are the risks for a colonoscopy?

There are only a few risks associated with a colonoscopy, some of these may include the following:

  • Reacting adversely to the sedative that is used for the procedure
  • Experiencing bleeding at the site where a biopsy (tissue sample) was done or if abnormal tissue or a polyp was removed.
  • Tearing in the rectal wall or colon, this is known as perforation, which is often from the scope or possibly a small tool that is used to perform a biopsy.

Your doctor is likely to discuss all the risks of the procedure with you in order to put your mind at ease. Bear in mind that any risks and complications associated with a colonoscopy are rare. When performed by a qualified and experienced specialist, it is a common, quick and generally safe procedure.

If, however, after your test, you experience any of the below, then contact your doctor immediately:

  • Rectal bleeding that is heavy
  • Extreme dizziness and vomiting
  • A firm or swollen belly (although bloating and cramping after the procedure is normal and may cause some discomfort, it is when these are extremely painful and impact your ability to function that there may be cause for concern)
  • Having severe abdominal pain

How do I prepare for my colonoscopy?

Before having a colonoscopy, you will need to perform a colon prep, this preparation will empty and clear out your colon because if there is any faecal residue left in the colon, this can obscure the visual for the doctor during the procedure. This colon prep is, in simple terms, a colon cleanse.

Your doctor will most likely send you a detailed list of dietary requirements and guidelines in order for you to prep (cleanse) your colon correctly. If you do not follow these guidelines effectively then the results of your test may be affected. A clear colon allows for clear visuals during the scope and more accurate results.

In order for your colon to be effectively emptied, your doctor may ask you to complete the colon prep which consists of the below factors:

  • Diet - Follow a specific diet a few days before the examination. Normally, the day before the procedure you will not be allowed to eat solid foods and any liquids must be clear, such as tea, water and not milk, broth or any dark coloured carbonated drinks, however, some doctors allow for light, clear broth and clear carbonated beverages. It is also advised that you avoid any red liquids in case they stain the colon or are mistaken for blood in the colon during the exam. In most cases, you will not be allowed to eat or drink anything after midnight of the night before your exam. You will need to stop drinking and eating anything six to eight hours before your colonoscopy.
  • Laxatives - Your doctor will prescribe a laxative that is either in a liquid or pill form for use one day before the procedure. In some situations, your doctor may ask you to take this laxative the night before and the morning of your procedure. Some laxative solutions include PicoPrep, Golytely or Nulytely. Liquid forms of laxatives come in a powder form and need to be mixed with water. These solutions can taste very salty and can often make your stomach cramp and feel mildly to very uncomfortable (depending on the brand used).
  • Enema - Your doctor may also suggest that you use an enema kit to effectively empty your colon. This is likely to be an over-the-counter kit, in which a fluid is injected into your rectum to cleanse your bowel. If this is not administered at home, it may also be administered on the day of your procedure by one of the nursing staff at the hospital.
  • Medications - It is best that you also tell your doctor about any medications that you may be on at least one week before your exam. These include medications for high blood pressure, heart issues or any iron-containing supplements. Your doctor is likely to also recommend that you stop taking any aspirin a few days before your exam. You should also not be taking any medications that may thin your blood, therefore you may need to adjust your dosages or stop these medications temporarily, but this should only be done under your doctor’s supervision.

To allow for your colon/bowel preparation to be a little easier, you can follow the below tips:

  • It may be easier to drink the laxative solution with a straw as this will allow for it to bypass your taste buds and go straight to the back of your throat.
  • Every time you take a dosage of the laxative solution, it may help to also drink something like apple juice to help get rid of the taste it leaves in your mouth.
  • Speak to your doctor about adding any flavoured drink crystals to the laxative solution.
  • You can even add lemon juice to the laxative solution or suck on a lemon wedge after you drink it.
  • Keep the laxative solution in the fridge as drinking it chilled can be more enjoyable. However, your doctor may ask you to drink the solution with warm water and in one go so that it can be easily absorbed (again, this will depend on the prescribed brand).

Your doctor may send you some information along the following lines:

Keep in mind that each doctor is different and may follow a different set of criteria and issue a slightly different guideline. However, the following is provided to give you an idea of what you may expect as well help you to prepare and put your mind at ease about your colonoscopy. This is not to be seen as the guideline that you should follow as your doctor is likely to issue you one.

Bowel prep for your colonoscopy:

Three days before your colonoscopy

This is normally your last opportunity to cancel the procedure, bear in mind that every doctor has a different cancellation policy, so it best that you speak to him to her about this.

Two days before your colonoscopy

Avoid foods containing seeds, nuts or any pips

One day before your colonoscopy


Eat a soft poached or boiled egg with white toast. Do not have any margarine or butter on the toast.

Have some tea or coffee without milk but with sugar if need be. Have a glass of clear liquid every hour after your breakfast.


Mix the first sachet of the laxative given to you from your doctor with 250 millimetres (one cup) of warm water. Stir the mixture well for two minutes and drink it followed by one cup of clear liquid every hour.


Mix the second sachet of laxative with one cup of warm water. Stir for two minutes and follow it with one cup of clear liquid every hour.

The following are acceptable liquids that you may drink:

  • Non-carbonated energy drinks
  • Clear apple juice
  • Vitamin water
  • Clear white grape juice
  • Water
  • Green, orange or yellow jelly

Extra notes to be taken into consideration:

  • Do not drink anything after 23:00 the night before your procedure
  • Your rectum may be raw and extremely sore from the frequent bowel movements - rash cream or ointment can be used for any anal discomfort caused from the laxative.
  • Unless otherwise instructed by your doctor, any medication that is due on the day of the procedure must only be taken once the colonoscopy is finished. Generally, once your doctor has reviewed your medical history and deemed it safe for you to do so:
    • All blood thinners must be discontinued before the procedure
    • Aspirin must be discontinued five days before the procedure
    • Diabetics will be advised to omit their medication on the morning of the procedure

On the day of the colonoscopy

Your doctor may suggest that you bring your own gown and slippers to be comfortable.

Your doctor will also give you a time to be at the hospital for the colonoscopy, this is normally a few hours before the procedure to allow for you to check into the hospital and get prepared for the test.

Post-procedure recovery instructions

Your doctor will likely recommend that you liaise with him or his nursing staff regarding any post-care questions you may have.

What should I expect when having a colonoscopy?

Prior to the procedure

You will generally be admitted to hospital as a day patient, and once you have checked in you will be assigned a bed in the day ward and given forms detailing personal and medical information as well as emergency contacts.

You will be issued a standard hospital gown (that opens at the back) and asked to change into it (having your own gown to put over it may make you feel more comfortable). 

Nursing staff will take your vitals (pulse and blood pressure) and if you are undergoing sedation for the procedure, the anaesthesiologist supervising this procedure will visit you to take a full medical history, find out if you have any allergies and discuss the sedation process with you.

You will generally not be offered any medication to calm your nerves before the procedure as these may coat the bowel and obstruct the view thereof.

Once the doctor is ready to perform the procedure, you will be wheeled into the procedure room.  People in the room during the procedure will include the gastroenterologist performing the procedure, the anaesthetist and one or two nursing staff and/or assistants.

During the procedure, you will only wear a gown and nothing else (underwear is removed for obvious reasons).

While some doctors may allow patients to be conscious for the procedure, most gastroenterologists will recommend that you undergo some form of sedation, not just for your own comfort but also to allow the procedure to proceed swiftly and without interruption.

Depending on your doctor’s recommendations, one of the following forms of sedation may be administered:

  • Conscious or “Twilight” Sedation: This is a mild to moderate form of sedation using a combination of sedatives (usually Propofol or benzodiazepine) and pain medications that are administered intravenously (via a vein in your arm).  Depending on the depth of the sedation, this will either leave you feeling comfortable and relaxed but not completely unconscious (you will be aware of and able to respond to auditory and tactile cues), or you may undergo a deeper form of sedation after which you will have absolutely no recollection of the procedure and feel as though you slept through the entire process.
  • General Anaesthesia: This is generally not a preferred method for colonoscopies, however, if it is used, it will be administered by a trained anaesthesiologist using a combination of Propofol (Diprivan) and pain medications.  You will not be conscious or responsive during the procedure, and a breathing tube for airway support will be required.
  • The SEDASYS®System:  Some professionally trained gastroenterologists and nursing teams may use this FDA-approved system to induce mild to moderate sedation with Propofol without the presence of an anaesthesiologist.

**My Med Memo:  The names “Propofol” and “Benzodiazepine” may be familiar to you as the administration of these were associated with the death of Michael Jackson in 2009.  This should, however, not make you feel anxious as his death was due to inappropriate and irresponsible use of these medications and numerous clinical studies have shown that when used appropriately and administered by a trained anaesthesiologist or doctor in the correct doses, these drugs are safe and effective for use in sedation for a colonoscopy.

During the colonoscopy

Prior to being sedated, you will be asked to lie on your side (usually the right side as this results in greater comfort and a quicker procedure time) on the examination table, having your knees drawn upwards towards the area of your chest.

When you are sedated, your doctor will insert the colonoscope into your rectum. The scope is long enough to reach the entire length of the colon. It will also contain a tube, known as a channel and a light that will allow for your doctor to inflate the colon with air, this allows for a clear view of the inner lining of the colon. As the scope moves through your colon, air will be pumped into it. This may create abdominal cramping or the urge to go to the toilet once the procedure is complete.

The scope also has a small camera at the tip of it to record images of the colon and send them to a monitor for your doctor to record and get a clear view of the lining of the colon. Your doctor may also insert small instruments through the channel to take some tissue samples known as biopsies, or to remove any abnormal tissue or polyps.

A colonoscopy is a relatively quick procedure and will take 20 minutes to an hour at most, depending on the findings and whether abnormal tissue or polyps need to be removed.

 View inside the colon

How the colonoscopy feels

As stated, the colon prep prior to the actual colonoscopy is often reported as being the worst part of the entire procedure for most patients as it results in diarrhoea, some mild cramping and anal discomfort.

In general, if you undergo any form of sedation for the procedure you will feel extremely relaxed or sleep throughout the procedure and have no recall of it afterwards.

If you are conscious during the procedure, however, then you may have some pain when the scope moves through the colon, and may feel the need to have a bowel movement or pass gas. If the pain you feel is unmanageable, then it is best that you tell your doctor. The machine used to remove secretions and stools is a suction machine and does not cause pain, but it can be noisy.

After the test, you may experience cramping and bloating and be very gassy from the air that was pumped into your colon.  Flatulence is a normal side effect and although it may seem embarrassing, you should not try to hold the gas in as this can increase cramping.  Nursing staff are trained professionals and will generally handle any flatulence you experience after the procedure with humour as they try to put you at ease.

If you had a biopsy during the procedure, or if anything abnormal was removed or polyps, then you may have mild discomfort at the site of the biopsy or a slightly bloody stool for a couple of days post the procedure.

After the colonoscopy

Once the exam is over, it will take you about 45 minutes to an hour to ‘wake up’ from the sedative. Even if you were conscious during the procedure, you may not remember anything if a light sedative was administered.

It is generally advised that you arrange for someone to drive you home after the procedure, as the sedative may make you feel drowsy and will often take a few days to fully wear off. It is best to go home and rest and not go back to work on the same day.

If a polyp was removed during the colonoscopy, your doctor may recommend that you stick to a specific diet for a couple of days to aid in the recovery of your colon.

Sometimes walking a few hours after your procedure can help pass the gas you are experiencing. 

When you have your first bowel movement, small amounts of blood in your stool is normal after this exam. Contact your doctor should you develop a high fever, have severe abdominal pain that is persistent, or if excessive blood is present when having a bowel movement.

What do my colonoscopy results mean?

After the colonoscopy, your doctor will review your results and then share his or her findings with you. These results can be negative or positive and are explained below:

Negative result

Although this may seem that the test has results that are concerning, in actual fact a negative test means that your doctor did not find any abnormalities in your colon.

If there was residual stool left in your colon, this may have prevented clear and complete visualisation. In this case, your doctor may recommend a repeat exam.

If you have an average risk of developing colon cancer, meaning there are no other risk factors for cancer, besides your age, then your doctor is likely to recommend that you wait 10 years after which you will have a repeat exam, given your colon preparation was correct and acceptable for this exam.

Positive result

If your colonoscopy is positive, it means that your doctor may have found polyps or other abnormalities in the colon.

Most polyps found are not cancerous, however, some can have precancerous properties. If polyps were removed during the colonoscopy, they would have been sent to a laboratory to be analysed and to determine if they are precancerous, cancerous or benign.

A follow-up exam will be dependent on the size and the number of the polyps that were found and removed. You may need to have more rigorous screening tests in the future. If one or two polyps were found by your doctor, and they were less than one centimetre (0.4 of an inch) in diameter, then your doctor may suggest you have a repeat colonoscopy in the next five or 10 years, however, this is dependent on your contributing cancer risks.

If your doctor found larger polyps, a larger number of polyps or any polyps that have specific cell characteristics, then you may be advised to have a follow-up colonoscopy within the next three or five years. However, this is also dependent on the cancer risks you may or may not have.

If any polyps were removed during the colonoscopy, then it may be suggested that you have a follow-up procedure in the next three months to a year. If abnormal tissue or a polyp was found in the colonoscopy and could not be removed during the exam, then your doctor may suggest that you have a repeat exam where a specialist will remove the polyps, this specialist is known as a gastroenterologist. In some situations, this specialist performs the initial colonoscopy.

Issues picked up with my colonoscopy

If there is a concern with the scope’s visual quality, then your doctor may recommend you come back for a repeat procedure in the near future. If your doctor was not able to get the scope all the way through your colon, then a virtual colonoscopy or a barium enema may be recommended in order to obtain a clear exam of your entire colon.

A barium enema is a form of an X-ray that is used to detect any abnormalities or changes in your colon (large intestine). In this test, a liquid (known as barium) is injected into the rectum in order to coat the inside of the colon, creating a silhouette thereof on a monitor, and allowing for any abnormalities to be highlighted.

What if there are any abnormalities detected during my colonoscopy?

If your doctor or specialist picks up any abnormalities, and an area needs to be better evaluated, then biopsy forceps may be pushed through a specific channel in the colonoscope in order for a tissue sample to be obtained, this is known as a biopsy. This tissue sample is then sent to a pathology laboratory for it to be examined by a pathologist under a microscope. A pathologist is a scientist who examines biopsies taken from body tissue for forensic and diagnostic purposes.

If an infection is suspected, then a biopsy can be taken for the culturing of bacteria, and in some cases, viruses and fungus, or the biopsy can be examined for parasites under a microscope.

When a colonoscopy is performed due to bleeding or blood being found in the stool, then this bleeding site is able to be identified and controlled during the colonoscopy procedure, if necessary a biopsy can also be done.

If there are polyps found they can also be removed through the colonoscope. Removing these polyps is vital in preventing colon cancer, or colorectal cancer, however, as stated, most polyps are found to be benign (not harmful) and do not result in cancer. Any additional procedures that are performed during a colonoscopy do not typically cause any pain. If a biopsy is done, it can be for a number of reasons and is not always a cause for concern.

Colon Cancer


What factors can affect the colonoscopy?

There are a number of reasons why you may not have the test performed or have results that are inconclusive. These contributing factors may include:

  • Having had a barium enema done within the week before your test can impact your doctor’s view of your colon and result in inconclusive results. The injection of a barium solution into your rectum for this procedure is vital for an X-ray of the colon but can adversely impact the results of a colonoscopy as it can block the view of the colon. It is therefore always advisable to disclose all previous medical procedures to your doctor before any further ones are scheduled.
  • Not performing an adequate colon cleanse or colon prep before your test can impact the colonoscopy. If you have any stool, also known as faeces left in your colon after the prep, then the colonoscopy may be cancelled and rescheduled once a proper colon prep is completed. Stool in the colon can block the view and visual your doctor has and can cover any abnormalities that need to be detected.
  • Due to the number of corners and turns in your colon, pain may be experienced during the procedure as the colonoscope goes around these corners (this is generally only if you are conscious during the procedure), or if you have had previous colon surgery.
  • Taking any iron supplements before the exam can result in your stool turning black and this can make it extremely difficult to clear out your colon of stool. It is best not to any iron supplements in the first week leading up to the test.
  • Drinking purple or red liquids such as fruit punch or grape juice as these can be mistaken as blood in the colon.
  • Eating purple or red foods such as cherries or strawberries, gelatine or grape flavoured lollypops.

What to know and think about regarding your colonoscopy

The below list is a few things that should be taken into consideration regarding a colonoscopy:

  • If you are pregnant or have an abdominal infection, this normally means you should not have a colonoscopy, unless your doctor has a vital health reason as to why he or she should perform one.
  • It is important to know that a colonoscopy when compared to another endoscopic colon text, for example, a sigmoidoscopy (which only examines the lower part of the colon), is more expensive. In most cases, your healthcare insurance will cover it if it is done for a specific purpose vital for your health. It is best to speak to your insurance company regarding this procedure and what is covered before scheduling it.
  • Most experts suggest that a testing schedule is created for colon cancer screening wherein you will have the exam done more frequently if you have a high risk of colon cancer. Speak to your doctor about your risks and whether he or she should create a schedule for you in order to detect any abnormalities and monitor your colon.
  • There are other tests available that are able to screen for colon cancer, these include:
    • Stool tests
    • Sigmoidoscopy – Just to recap, this is an endoscopy done of the lower portion of your colon, therefore less area of the colon is covered during this procedure.
    • Computed tomographic colonography – This test, which is also known as a virtual colonoscopy (we will get into more detail about that in the next section), uses a specialised X-ray machine to examine the colon and produces detailed images in doing so.

      • The screening test that you choose is dependent on your preference, risk and of course, what your doctor recommends, as he/she will know, in light of your full medical history, what is best for you and your current state of health. 

I have some more questions regarding my colonoscopy…

What is virtual colonoscopy?

A virtual colonoscopy is an alternative to a colonoscopy. It is a procedure that utilises CT (computerised tomographic) scanning to get a visual of your colon that is very similar to those that are obtained from a direct observation, known as a colonoscopy. These images are created using computerised tomographic visuals, this means that they do not look like real-life images, they are known as virtual images. A lot of people prefer this kind of procedure as it is less invasive and is not associated with much discomfort, apart from the colon prep prior to the exam.

A colon prep for a virtual colonoscopy is similar to that of a standard colonoscopy, wherein your colon will need to be cleared out by using laxatives and sticking to a specific diet a day or so before the procedure.

During a virtual colonoscopy, a tube will be inserted in the rectum and anus, after which it will pump air into the colon. Once the colon is inflated, the CT scans can take place. These scans are then analysed and manipulated in order for them to form a clear and virtual visual of the inside of the colon. When a visual colonoscopy is performed correctly, it can be a very effective means to see the inner lining of the colon. It is even possible for a virtual colonoscopy to detect polyps that are hidden behind folds in the colon, these are sometimes undetected in a colonoscopy.

However, there are a number of limitations that come with a virtual colonoscopy, these may include:

  • A virtual colonoscopy may find it difficult to detect and identify polyps that are less than five millimetres in diameter, however, small polyps such as these are easily detected in a colonoscopy.
  • A virtual colonoscopy finds it extremely difficult to identify premalignant (precancerous) lesions or flat cancers or lesions that are not protruding but have similarities to polyps.
  • A virtual colonoscopy cannot remove any polyps that are detected during the test. Colon polyps can be found in roughly thirty to forty percent of people. If any polyps are found in a virtual colonoscopy, then a colonoscopy will have to be scheduled following this in order to remove them.
  • A virtual colonoscopy will expose you to some radiation, however, unless you are pregnant, this does not cause any harm.
  • A virtual colonoscopy will not permit for newer techniques being developed to be used in order to distinguish between lesions that do not need to be removed and abnormal ones that need to be removed or biopsied.

Due to the above drawbacks, having a virtual colonoscopy done will not replace a colonoscopy as a means for primary screening for those who have an increased risk of colon cancer or polyps. However, a virtual colonoscopy is often an option for those who have an average risk of developing colon cancer and polyps and will not or cannot undergo a colonoscopy.

Bear in mind that having a virtual colonoscopy done wherein abnormal lesions are found, will need to be followed-up with a colonoscopy to have these removed or biopsied. This means that you will have to undergo the bowel prep on two separate occasions, which, as stated, can often be the worst part of the entire experience for some.

Are there any new developments in colonoscopies?

There are a number of new developments in colonoscopies. The majority of these are centred around the improvements of the detection ability of the procedure in finding lesions that are hidden, small or flat. As well as this, steps are being taken to improve the ability of the colonoscopy to determine whether a polyp needs to be removed or a biopsy needs to be done at the time of the initial colonoscopy. This is vital due to the fact that a lot of money and time that goes into the removal of these polyps or lesions, this includes sending them to labs for examination that is often unnecessary. Therefore, in future colonoscopies will theoretically have the ability to determine if abnormalities are cancerous or noncancerous at the time of the colonoscopy.

A higher resolution of images has become a standard for colonoscopies, as well as this, magnifying these images may also aid in finding abnormalities that are ‘hidden’.  Therefore, improving the detection of lesions or polyps.

An imaging technique known as narrow-band imaging makes use of a specialised light transmitted via a wavelength, to enhance the visibility of the pattern of the small blood vessels found below the colon’s lining. The pattern that is formed from this light is different between normal, precancerous and cancerous tissues. Examining this pattern will allow for the detection of smaller and flat lesions to be identified more easily and allow for the doctor to make a decision as to whether the lesion should be removed or biopsied, without having to wait for the microscopic examination results from the lab.

Another technique known as chromoendoscopy makes use of stains or dyes being sprayed into the lining of the colon in order for the doctor to distinguish between the normal lining and the neoplastic (the growth of tissue that is deemed abnormal) tissue, which may be classified as premalignant, malignant or benign (not considered cancerous) tissues. This allows for the doctor or specialist to determine if any of these should be biopsied or removed.

A fluorescence endoscopy makes use of fluorescent chemicals that are known as fluorescein-labelled, that are sprayed on either the inner colon lining or are injected intravenously. These fluorescent chemicals are absorbed more by the abnormal cells in the lining of the colon than the normal cells. With the use of a special lighting, the abnormal areas can be seen to be removed or biopsied.

There are also accessories and colonoscopes that allow for a retrograde image of the colon, as well as an antegrade view given from the top of the colonoscope. Therefore, the images are obtained from a 180-degree view to allow for hidden lesions to be identified, specifically ones that are hiding behind the folds in the colon, these are often missed from the forward-viewing, standard colonoscope. There is also research being done to try and develop a self-advancing colonoscope, therefore the scope would move through the colon on its own and not require the doctor’s guidance.

Many of the aforementioned techniques, besides the use of high-resolution images, are considered to be experimental.

On a final note, the MRI, which is magnetic resonance imaging, can also be utilised as a means to examine the inside of the colon that is very similar to a virtual colonoscopy. The fact that there is no radiation when having an MRI is the major advantage of the procedure. However, the limitations are very similar to those of a virtual colonoscopy.

How long does it take to get a colonoscopy?

A colonoscopy is a very short procedure and will normally only take a number of minutes. In most cases the exam will take about 30 minutes, this includes taking 12 minutes to insert the scope and 12 minutes to remove it. However, if polyps need to be removed or a biopsy needs to be done, this may take longer depending on the number and size of the polyps.

Please note that this does not include the prepping time at the hospital before the procedure, the sedation or waking up from the sedation. Your doctor may ask you to be at the hospital a few hours before the exam, you will be booked into a room as an outpatient in the hospital (meaning you are not likely to spend the night but will go home on the same day). After this, your doctor and possibly anaesthetist will come to see you and nursing staff will take you into the room for the procedure.

What are the side effects of a colonoscopy?

A colonoscopy does not normally have any significant side effects. Gassiness (flatulence), abdominal pain and bloating are the most common side effects of the procedure. As well as this, you may feel extremely drowsy from the sedation.

The procedure is considered to be a safe one with very little risks. There is a very small risk of perforation or tearing occurring in the lining of the colon from the scope. However, this only occurs in one in 1,000 patients.

Is sedation needed for a colonoscopy?

The use of sedation is done at the decision of your doctor. In some cases, you may have a colonoscopy done with no anaesthesia whatsoever. However, most people are consciously sedated. This means they are administered a number of sedation and pain drugs to help put them at ease, make them feel relaxed and stop them from feeling any pain during the procedure. In this case, they are semi-conscious while they are undergoing the colonoscopy, but do not remember much after the exam.

Can you drive home after a colonoscopy?

It is best, due to the effects of the sedation, that you get someone to drive you home or help you to get home through means of public transport as you are likely to feel very loopy and lightheaded after the sedatives and painkillers. You should not drive for at least 12 hours after the colonoscopy.

Is it safe to drink alcohol the night before my colonoscopy?

Some patients think it is acceptable to drink alcohol the night before their colonoscopy, however, even though it can be a clear liquid in some forms, it is not advised that you drink any alcohol before your procedure. This is because alcohol can leave you dehydrated and with the colon prep you may already be suffering from this.

In addition, alcohol thins your blood and may increase the risk of bleeding from a biopsy site or if you need to have a polyp removed.

Disclaimer - is for informational purposes only. It is not intended to diagnose or treat any condition or illness or act as a substitute for professional medical advice.