A colonoscopy is a type of imaging study in which a doctor uses a particular scope called a colonoscope to examine the colon's lining.
A doctor may recommend a colonoscopy to evaluate the colon for cancerous lesions, identify areas of bleeding, or diagnose other gut-related disorders.
Before the procedure, a doctor will prescribe a colonoscopy preparation or prep. While different prep types exist, the aim is always to empty the colon of fecal matter so that a doctor can view it clearly.
The colonoscopy procedure involves inserting a thin scope with a light on the end into the rectum. The doctor will advance the scope through the colon to examine it. They may also remove samples of tissue for biopsy or remove an outgrowth of tissue known as a polyp.
In this article, we look at how to prepare for a colonoscopy appointment and what to expect before, during, and after the procedure.
The week-long preparation process will include several different steps as the day of the colonoscopy gets closer.
One week before
A doctor is likely to recommend specific dietary changes in the week leading up to a colonoscopy.
While canned or cooked vegetables are acceptable to eat, people should avoid the following foods during this week:
- grains, including brown rice, oatmeal, and wheat bread
- seeds, including poppy or sesame seeds
- whole kernel corn
- raw fruits and vegetables
A doctor may also recommend that people stop taking certain medications that could increase the risk of bleeding during a colonoscopy. Examples include blood thinners, such as warfarin and clopidogrel, and nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen.
People will need to stop taking these medicines about 3 to 7 days before the procedure. A person should never discontinue their medication without a doctor's specific recommendations.
Two days before
At this point, people should drink plenty of water or other liquids to ensure that they do not become dehydrated when they begin their bowel prep. Drinking around eight 8-ounce glasses of water a day can help to reduce the risk of dehydration.
A doctor may also recommend avoiding foods that are red or orange at this point, as these could make a person's colon look like it is bleeding.
24 hours before
It is crucial to consume only clear liquids in the 24 hours leading up to the colonoscopy.
Examples of acceptable clear liquids include:
- clear broth or bouillon
- coffee or tea, but with no milk or creamer added
- electrolyte-containing beverages, such as sports drinks
- strained fruit juices with no pulp
In general, if it is possible to see through the food or drink, it should be acceptable within a clear liquid diet. However, a person should always consult their doctor with any questions about specific foods.
A doctor will often prescribe an oral solution to drink to help clean out the colon. This solution will cause the person to have frequent bowel movements until there is no fecal matter left in their colon. Examples of oral solutions include GoLytely, Colyte, NuLytely, and TriLyte.
These solutions are likely to have different dosage methods. Sometimes, a doctor will prescribe drinking the entire solution the night before the colonoscopy. Other times, they will recommend drinking one portion of the solution the night before and the remainder on the day of the examination.
The solution is intended to make a person go to the bathroom. Their bowel movements will turn into diarrhea.
The bowel prep can sometimes make a person feel nauseous, bloated, thirsty, or dizzy. If this occurs, the individual should give themselves a break of at least 30 minutes from drinking the prep and slowly sip on clear fluids. If they can tolerate returning to drinking the prep, they should.
With a doctor's permission, it may be possible to add a powdered drink solution that is not red, blue, or purple to the prep to improve its taste.
During the bowel prep, a person may benefit from:
- staying near a bathroom so that they can go to the toilet easily
- wearing elasticated pants that are easier to pull down
- drinking clear liquids after swallowing the prep to remove the unpleasant taste
- applying petroleum jelly around the anal opening or using baby wipes to reduce irritation to the anus
The bowel movements will eventually turn clear or yellow. This change signals that a person's colon is likely to be clear of fecal matter.
In case of problems with constipation, a doctor may also recommend using a stool softener to make stools easier to pass.
By the time of the colonoscopy appointment, a doctor will expect a person to be passing only clear to yellow-tinted liquid after following the recommendations for drinking the colonoscopy prep solution.
The individual's doctor will explain the procedure. The person will also meet the nursing staff who will be in the room with them during their colonoscopy, as well as anesthesia representatives who will be providing sedation. This is a good opportunity for the person to ask any questions they have regarding the procedure, including risks and benefits.
A member of the medical staff will insert an intravenous (IV) catheter into the person's vein so they can receive medications during the procedure.
The person will then go to the colonoscopy suite. An anesthesia professional will start giving medication via the IV, which will cause the person to go to sleep. Most of the time, they will still be breathing on their own throughout the procedure.
A doctor will insert the colonoscope through the rectum and advance it to begin the examination. They will look for irregularities in the colon's lining and, if they find anything suspicious, such as a polyp, they might take a biopsy or remove it, if possible.
Ideally, a person's colon prep will be so effective that a doctor can advance the colonoscope far enough into the colon to see where the small and large intestines join.
When the doctor has completed the examination, they will remove the scope. The anesthesia professional will stop administering medication, and the person will wake up.
It is not unusual to feel sleepy or groggy after the procedure. For that reason, a person should always have someone else available to drive them home from the appointment.
Following a person's colonoscopy, a doctor will talk to them about any initial findings. This might include reviewing images from the colonoscopy.
However, there might be a wait of several days before the results of the colon biopsy are available. The doctor should be able to advise the person about how long they might have to wait.
If a colonoscopy is positive, meaning cancerous or precancerous cells are present, the doctor may recommend further interventions. These can include additional colonoscopies or even surgery.
Colonoscopy risks tend to be few.
The most serious potential complication is a tear in the intestine's lining, although this is rare. A tear can allow the intestine's contents to spill into the abdomen, which is very dangerous. If a tear occurs, surgery will be necessary to repair the lining.
Other possible risks include bleeding from a biopsy or polyp removal site. Some people may also experience adverse reactions to either the colonoscopy prep or the medication they had during the procedure.
While colonoscopy preparation can be unpleasant, it is a vital process to ensure a successful examination.
If a doctor cannot see enough of the colon, they may recommend performing another colonoscopy to ensure that they have not missed anything. As a result, it is best to stick to the original preparation plan.
A doctor will make follow-up recommendations if the colonoscopy shows cancerous tissue to be present.