Colonoscopy, Polyps, and other Colon Examination Methods

A colonoscopy is a common medical procedure that enables your surgeon to directly examine the inner lining of the colon and rectum using a flexible tube equipped with a camera. With good bowel preparation and in expert hands, colonoscopy is undoubtedly the most accurate and effective way of investigating the large bowel.

Mr John Stebbing, distinguished consultant surgeon, provides an expert insight into the reasons for undergoing a colonoscopy, how colon abnormalities are managed, alternative colon examination methods and reasons for follow-up colonoscopy.

When is a colonoscopy recommended?

A colonoscopy is performed for various reasons, such as:

To screen for polyps and colorectal cancer in patients either with a high-risk genetic predisposition or who have submitted a stool test called FIT which identifies blood in the stool.
To investigate symptoms, such as rectal bleeding, abdominal pain, chronic diarrhoea and unexplained weight loss.
To monitor chronic conditions, such as inflammatory bowel disease (IBD).
To deliver surveillance follow-up after previous treatment for polyps or colorectal cancer.

If found, how are colon abnormalities managed?

There are quite a lot of benign findings at a colonoscopy that do not need treatment, for example diverticulosis (natural wear-and-tear outpouchings) or angiodysplasia (localised blood vessel abnormality like a birthmark).

If colorectal cancer is identified or suspected, then a biopsy is taken and the area marked with a tattoo to help identify the position in the bowel at later surgery. Biopsies are also routinely taken for patients with obvious inflammation or, even with a normal colon, in patients with chronic diarrhoea.

Polyps are one of the most common findings during a colonoscopy and, in over 95% cases, can be treated by polypectomy there and then. A colonoscope includes a small channel to allow the passage of specialised tools such as snares to remove polyps safely, with or without the use of diathermy cautery. Once removed, your surgeon will send polyps to the laboratory for histopathological analysis.

A few polyps are larger or more complex, requiring further discussion and planning for advanced treatment, such as endoscopic mucosal resection (EMR) or, occasionally, surgery.

In cases where colorectal cancer or complex polyps are found, there may be need for additional investigations and these patients should be discussed at a colorectal multidisciplinary team (MDT) meeting to agree on the best treatment options.

Are all polyps harmful?

Not all polyps are harmful. Most are found as an incidental finding in patients with symptoms or at a colonoscopy for screening. There are quite a few types of benign polyps and their nature and number will set a risk profile for a patient. Of most interest are benign growths called adenoma and a family of polyps known as sessile serrated lesions, as these are associated with the risk of colorectal cancer.

Regular surveillance with colonoscopy may be recommended to detect further polyps and to reduce the risk of colorectal cancer.

What are alternatives to a colonoscopy?

Colonoscopy is considered the “gold standard” for investigation of the large bowel, as it offers the opportunity for thorough, direct inspection of the bowel lining with a high degree of accuracy and over 95% procedures achieving a complete examination. It combines this diagnostic excellence with the ability to treat polyps or take biopsies at the same examination.

Patients should, however, be aware of alternatives to colonoscopy which include:

Flexible sigmoidoscopy: This procedure examines the lower part of the colon, specifically the rectum and sigmoid colon and may be appropriate for certain symptoms, for example bright rectal bleeding in younger patients.
CT colography (“virtual colonoscopy”): This test uses a CT scanner to capture images of the colon and rectum following administration of oral contrast and insufflation of the bowel with gas. It also allows review of other structures in the abdomen/pelvis, so it may pick up incidental findings. The test can only detect lower GI diagnoses which create deformity of the colonic surface such as diverticula or larger polyps and can never, therefore, match the diagnostic potential of direct colonoscopy,
Colon capsule endoscopy (CCE): This test involves a patient following a very thorough bowel cleansing regime before swallowing a small capsule equipped with a camera which captures images as it passes through the gastrointestinal tract. The images are then reviewed by a trained specialist. This test has potential but currently only achieves a complete assessment of the colon in 60-70% of patients and, of course, cannot deliver any treatment.

The choice of examination will depend on your individual health needs, preferences and the advice of your surgeon.

How often should people undergo a colon examination?

The frequency depends on several factors, including your individual risk and the findings of previous examinations.

Repeat colonoscopy is generally recommended for:

Patients who have previously been treated for colorectal cancer - within 1 year for patients with previous incomplete colonoscopy or known residual polyps; then, 3 years later.
Patients with polyposis syndromes (multiple polyps of certain sub-types) - usually monitored every 12-18 months.
Patients with a specific genetic risk such as Lynch syndrome - colonoscopy every 2 years.
Patients with previous polyps judged to be at higher risk - colonoscopy at 3 years.
Patients with a family history of colorectal cancer - should be assessed by an expert to advise on the need for regular colonoscopy (every 5 years) or a one-off examination at age 55 years.
Patients with established IBD - intervals determined by personalised risk assessment.
Patients with a normal baseline colonoscopy and with no specific risk factors who simply choose to use direct colonoscopy as their personal choice for bowel screening - colonoscopy every 5 years.

As it can be seen, decisions about repeat colonoscopy require careful personal risk assessment and consulting with your surgeon about the most suitable screening or surveillance. This will help you to use colonoscopy to your best advantage and may reduce the risk of colorectal cancer.

To book an appointment with Mr Stebbing, head on over to his Top Doctors profile today.