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. The doctor can also remove polyps or tissue for a biopsy at the same time.
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. There are various approaches, but they all aim to empty the colon of fecal matter so that a doctor can view it clearly. The preparation may start up to a week before the colonoscopy.
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.
In this article, we look at how to prepare for a colonoscopy appointment and what to expect before, during, and after the procedure.
It may mean canceling the procedure. If the colonoscopy goes ahead, the doctor may miss a lesion, or the person may need to repeat the procedure.
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.
The gastroenterologist will work with the individual during the consultation to decide how long they should suspend using a specific medication before and after the colonoscopy.
The consultation also is a good time to ask any questions about the procedure, including the risks and benefits.
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 reduce the risk of dehydration.
A doctor may also recommend avoiding red or orange foods at this point, as they 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 without 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 if they have 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
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, a person potentially can 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 elastic-waist 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 from the bowel.
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.
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 anesthesiologist who is part of the procedure team will administer sedatives to the person via the IV and be responsible for keeping their airway safe throughout the procedure.
Once the person is sedated, 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.
The gastroenterologist will evaluate each polyp individually. Based on its size, shape, and location, the doctor will determine the best technique to remove the polyp. They may also take a sample of tissue for testing in the laboratory, known as a biopsy.
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.
After a colonoscopy, the person may have to attend another appointment to discuss the results or any findings of tests.
During the appointment, the doctor will explain any findings. This might include reviewing images from the colonoscopy.
Possible results may be:
- Negative: There are no growths or polyps.
- Growths or polyps: The doctor has removed polyps and may wish to follow up after testing.
- Bowel cancer: The doctor may have taken a biopsy. If they suspect cancer, they will talk to the individual about what to do next.
- Other conditions: If there are signs of Crohn’s disease, diverticulitis, ulcerative colitis, or another condition, the doctor will discuss the next steps with the person.
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.
There are some risks involved in a colonoscopy. The doctor should explain these to the person before the procedure.
- complications relating to anesthesia
- rectal tears
- post-polypectomy electrocoagulation syndrome (PPES)
- colon wall perforation
Severe complications are rare, and experts consider the procedure relatively safe.
PPES can cause severe abdominal pain several hours after the procedure. Treatment usually involves bowel rest and antibiotics.
Colonoscopy preparation can be unpleasant but is vital for ensuring a successful procedure.
If the results are not clear, the person may need to repeat the procedure.
For this reason, a person should follow the preparation plan. A doctor will make follow-up recommendations if the colonoscopy shows that further investigation or treatment is necessary.