When should you consider having a colonoscopy?

A colonoscopy is an exam of the colon and rectum using a long flexible tube with a camera and light at the end. It is used to investigate changes or abnormalities within bowel function, and is one of the standard tests for diagnosing colon cancer, but it has a variety of applications in the prevention and early diagnosis of many colorectal diseases. In this article, a consultant colorectal surgeon explains the ways doctors utilise colonoscopies, what happens during them, and when patients should undergo one.

What is a colonoscopy?

A colonoscopy is one of the most effective ways to examine colorectal health, used both for diagnostic and therapeutic purposes. It is conducted using a long, flexible tube fitted with a camera and light (the scope) at the end. The tube is hollow so that, if need be, tools and devices can be passed through it. A colonoscopy only examines the large intestine, colon, rectum, and anus; other structures of the digestive system require a different endoscopic exam. T

The purpose of a colonoscopy is to:

Evaluate symptoms and concerns of the patient
Monitor disease progression
Intervene as early as possible for illnesses of the colon and rectum

The key characteristic of colonoscopies is that they are minimally invasive examinations with no radiation or incisions, but still yield high-resolution, real-time, and full-colour visualisation of the intestinal structures.

What happens during a colonoscopy?

Before a scheduled colonoscopy, the patient must follow a liquid diet for around two days in order to ensure that there are no obstructing elements in the colon during the exam. Patients will furthermore need to take a laxative or undergo an enema (or both) to completely empty the colon.

Patients are partially or fully sedated during the procedure to keep them calm; this is not a painful procedure, but some patients may feel anxious or uncomfortable. Physically, the sensation is similar to pressure or swelling within the rectum.

After the procedure, patients remain for a short period in a recovery room so that the sedation may wear off, and then they can leave the clinic. They can return to their normal diet and medications on their doctor’s advice, dependent on their condition. Patients might experience some cramping or the need to pass gas within the following hours, which should subside within a day.

Who should get a colonoscopy, and when?

Most patients are encouraged to undergo a screening colonoscopy at the age of 45, provided they are within an average risk group of developing colorectal cancer. If nothing of note is found during this examination, then typically the patient does not need another colonoscopy for at least the next 10 years.

Patients are considered within an average risk group, and thus do not need to undergo a colonoscopy before 45 years of age, if they:

Don’t have a personal or family history of colorectal cancers, polyps, or inflammatory bowel diseases
Have never had radiotherapy to their pelvis or abdomen
Don’t have a hereditary condition like familial adenomatous polyposis or Lynch syndrome
Do not have chronic constipation, diarrhoea or other changes to bowel habits
Do not have persistent bowel pain or bloating
Do not have blood in the stool or bleeding from the rectum
Maintain a healthy, fibre-rich diet
Have not undergone unexplained weight loss or gain
Are not heavy drinkers or smokers
Do not have obesity

If doctors do find polyps or other abnormalities within the colon, then this patient, regardless of their personal or familial history, is at risk of developing colorectal cancer and should undergo regular screening thereafter. Polyps are typically removed when discovered so that the cells may be analysed in a laboratory to assess the risk of cancer development.

After the age of 75, regular screening is not as emphasised as it can be a more complex procedure at an advanced age, but if the patient begins to struggle with colorectal symptoms like blood in stool or diarrhoea, then their case will be considered by their doctor; there may be complications with comorbidities, their current medications, and the sedation.

Colonoscopies are used in the diagnosis and monitoring of several colorectal ailments, such as inflammatory bowel disease, and most significantly, colon and rectal cancers. Patients between the ages of 45 and 75 should undergo a colonoscopy at least once every 10 years, so long as they aren’t considered high-risk and the doctor does not find anything concerning, such as polyps, during the procedure. Patients who are considered high-risk are those who have a prior or family history of colorectal diseases, have previously received radiation therapy to their abdomen or pelvis, have a poor diet, smoke or drink a lot, and have a genetic condition such as familial adenomatous polyposis or Lynch syndrome. After the age of 75, there are more risks associated with the procedure, and so patients are considered on a case-by-case basis on the necessity for a colonoscopy.