What Exactly is a Colonoscopy? | Knowledge is Power

What do you tell a patient having a colonoscopy?

A colonoscopy is the greatest tool used to detect colorectal cancer and other bowel abnormalities. A successful colonoscopy requires timely preparation, clear communication and a multi-disciplinary approach.


  • Specializes in OR,PAR,PainMgmt,GenSurg,Cosmetic,Imaging,Endoscopy. Has 23 years experience.
What do you tell a patient having a colonoscopy?

A colonoscopy is a test that is done by a specialist doctor called a gastroenterologist. The doctor will use a colonoscope (a scope) which is a long flexible tube with a camera at the tip end to visualize the entire colon. The main goal for having a colonoscopy is to reduce the number of people who develop colorectal cancer and those who die from it.

A colonoscopy is usually done as a day case procedure at a hospital or a private clinic. It is one of many surveillance tools used to investigate colorectal cancer. In fact, it is the best screening tool by which all other tests are compared against. A colonoscopy is considered as the gold standard and a life saver in detecting and treating early colon cancer.

According to the Canadian Cancer Statistics 2021 Report, colorectal cancer accounts for 12% of all cancer deaths. In actual figures that means an estimated 9,600 Canadians “will die from colorectal cancer”. Similarly in the United States as stated by Cancer.Net Statistics 2022 approximately 151,030 cases will be diagnosed this year with colorectal cancer. These statistics and many other factors make it necessary for people to have a colonoscopy procedure.

Why is a Colonoscopy Performed?

There are many reasons why a patient will have a colonoscopy done and some of the reasons are:

  • To screen for colorectal cancers and dysplasia
  • To explore causes of symptoms like unexplained abdominal pain, loss of weight, anemia, uncontrolled vomiting, diarrhea
  • To check for blockages or narrowing of the colon
  • To assess for inflammatory bowel diseases I.e. Crohn’s and ulcerative colitis
  • To investigate any infections within the colon
  • To obtain biopsies during a colonoscopy procedure that can be analyzed in the lab
  • To follow up on previous findings like polyps or tumor removed  
  • To rule out or confirm unusual results from other screening tests I.e. CT or X-Rays
  • To check for blood in the stool or excessive rectal bleeding
  • Post-surgical treatment like major colon resection
  • To treat certain conditions, therapeutic treatments can be applied directly to the area to close a bleeding blood vessel with heat, clips or inject specialized medication, remove polyps or tumor

Is a Colonoscopy for Everyone?

Certainly not, the physician decides who gets to have a colonoscopy based on the following criteria.

  • Patients who are at risk of colorectal cancer due to family history
  • Patients who have drastic bowel changes or various types of bowel conditions
  • Anyone at the age of 55 in Canada should have a coloscopy done to screen for cancer even if they have no symptoms.
  • In the U.S. the screening age is 45 – 75 years or 40years if at higher risk for developing colorectal cancer, especially those of African American heritage

How Do You Prepare for a Colonoscopy?

There are certain measures that should be followed before the patient has a colonoscopy procedure.

  • The patient is advised to stop eating solid foods that contain seeds at least a week before the procedure
  • The patient can consult with their physician when to stop taking any  medications like blood thinners – usually 3 to 5 days depending on the type of blood thinner
  • The patient must begin fasting after breakfast the day before the procedure Usually recommended to have early breakfast the day before the procedure
  • The day before the procedure the patient should start taking the bowel preparation (bowel prep) solution after breakfast to cleanse the colon
  • Once they commence the bowel prep drink the patient should not eat any solids anymore until after the procedure
  • The patient should drink plenty of clear fluids on the day they take the prep to stay hydrated but avoid any colored fluids. No fluid intake at least 4hrs prior to the procedure
  • Patients are encouraged to stay at home after starting the bowel prep because they would need to use the washroom quite frequently
  • If the patient is in-patient the nurse will remind the patient when to start taking their bowel prep and an NPO sign will be put above the patient’s bedspace

Good bowel preparation is paramount to the success of the colonoscopy procedure because the physician will be able to see clearly inside the colon. A few hours before the colonoscopy procedure begins the nurse will ensure that the patient has a functional intravenous ( IV ) access. The IV access will be used to give the sedative medications during the procedure.

Communicating with the Patient

It is beneficial to the patient to have the procedure explained to them by the healthcare professional looking after them. The nurse has the opportunity to address any concerns that the patient may have prior to having the procedure. Many patients may feel very anxious on the day of the procedure. Therefore, the healthcare professionals must create an environment where patients are free to ask questions and reassure them.

However, due to anxiety, it is always good to not overwhelm the patient with lengthy details about the procedure. Only give them information that is necessary to prepare for the procedure. It is vitally important to let the patient know that colonoscopy is a short and safe procedure however, possible complications can occur. It is ethical practice to mention to the patient some of the complications of having a colonoscopy procedure. This allows the patient to make an informed decision about their care. The following examples are some of the possible complications that your patient may want to know.

Possible Complications of a Colonoscopy

The following symptoms may occur immediately post-procedure or days after the procedure. Some patients may experience only one of the symptoms or a combination of symptoms or almost all of the symptoms. If a patient has any of these complications while at home, they need to see their doctor or visit the emergency department immediately.

  • Bowel perforation especially if large polyps were removed
  • Adverse reaction to sedative drugs
  • Excessive rectal bleeding after removing polyps
  • Severe abdominal cramps or pain
  • Vomiting
  • Fever
  • Difficulty pooping or passing gas
  • Dizziness
  • Infection

How Do They Perform this Colonoscopy Procedure?

As we mentioned at the beginning it takes special equipment to be able to do the colonoscopy procedure. When the patient is taken into the procedure room, they will get connected to a monitoring machine and their vital signs will be checked regularly. The doctor and the nurse will explain what will happen while the patient is in the procedure room and ensure that the patient understands.

Medications for Colonoscopy

Sedation will be given to the patient intravenously and in most cases that will either be light or moderate sedation. Common drugs given for this type of sedation are benzodiazepines (midazolam) and opioids (fentanyl). But there are other times when deep sedation or general anesthesia may be required especially if the case is very complex. For these two types of sedation, an anesthesiologist will be involved to administer the drugs. Some patients choose to have a colonoscopy without sedation but these make up a very small percentage.

After giving the sedation the scope will be advanced into the rectum. Some air will be pushed into the colon as the scope glides inside the colon. This air helps to open up the folds within the colon and enables the doctor to see clearly. With light or moderate sedation, the patient may feel drowsy or sleep during the procedure as long as they experience no pain. At other times the patient may even get to watch the procedure. The whole procedure usually takes about 30mins and then the patient will be taken to the recovery area.

Recovering after a Colonoscopy

In the recovery area, the patient’s vital signs will be monitored until they are ready to be discharged. Sometimes after 30mins, the patient will be able to go home but it varies from patient to patient. Post-procedure the patient will be encouraged to pass the gas if they experience any bloating.  

After the colonoscopy, the physician will briefly explain the findings to the patient before they are discharged. The patient should have a responsible adult to look after them at home at least for 24 hours after the procedure. The reason is that after receiving sedation during the procedure the patient may be cognitively impaired and not be able to do or remember certain things.

Finally, when all the discharge criteria are met the nurse will give verbal and written discharge instructions to the patient. The discharge instructions should address issues about:

  • When to resume a normal diet
  • When to take their blood thinner if that applies to them
  • What activities they can & cannot do I.e. no driving, no alcohol for 24hrs
  • Any follow–up arrangements
  • What complications to look for
  • Contact information in case of emergency

This is some of the information that patients would like to know when having a colonoscopy procedure.


American Society of Anesthesiologists. Colonoscopy

American Society for Gastrointestinal Endoscopy. Understanding Colonoscopy

Canadian Cancer Society: Colorectal Cancer Statistics Report 2021

Cancer.Net, Colorectal Cancer: Statistics,  Approved by the Cancer.Net Editorial Board, 02/2022

Centers For Disease Control And Prevention. Colorectal Cancer Screening Tests.

Cleveland Clinic. Colonoscopy

Martin L.J. MD, Medically reviewed on March 01, 2020. WebMD, Colonoscopy Risks

Medical News Today. What to know about sedatives 

National Institute of Diabetes and Digestive and Kidney Disease. Colonoscopy    

Pichardo G. MD, Medically reviewed on February 14, 2021.WebMD, How to Prepare for a Colonoscopy    

SGNA. Patient Care Safety – Recovery & Discharge ( n.d.)

Julita Mclellan is an RN with experience in OR, PACU, Pain Management, Gen-Surg, Cosmetic Surgery, Interventional Radiology & Endoscopy. She enjoys learning new skills and sharing her knowledge with student nurses and new nurses.

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