When to consider a colonoscopy

Written by: Dr Aathavan Loganayagam
Published: | Updated: 30/08/2019
Edited by: Laura Burgess

Each year around 900,000 colonoscopies are performed in the UK. By 2020, medical authorities expect well over a million colonoscopies to be performed in UK hospitals. But it raises the question, when is the procedure really needed?

We’ve asked expert gastroenterologist Dr Aathavan Loganayagam: will all of these colonoscopies be truly necessary?

Why have a colonoscopy?

A thin, flexible camera called a colonoscope is inserted into the anus through the bowel to see if there are any abnormalities in the lower intestine or colon. The camera enables the specialist to check the lining of the bowel for polyps (pre-cancerous growths) and remove them. The most common reason for the procedure, however, is to check for bowel cancer.

Around 17,000 people, who are mostly over the age of 50, are diagnosed with bowel cancer each year in the UK. If the disease is found early, around 90% of cases can be treated successfully meaning that early diagnosis of bowel cancer is vital.

How is bowel cancer tested for?

The National Bowel Cancer Screening programme uses a ‘poo test’ (or Faecal Immunochemical Test) to screen for the disease. The test, which is sent to people on their 55th birthday, is used to detect traces of blood that may be a sign of early bowel cancer. A further test is offered every two years to men and women aged 60 to 74. People older than this can ask for testing every two years.

Abnormal results suggest that there may be bleeding within the gastrointestinal tract that requires further investigation. Those with abnormal results are invited for a colonoscopy.

As of August 2018, the UK government agreed that future bowel testing in England will start from age 50.

Why may colonoscopies be over-used?

The number of colonoscopies has risen faster than the rate of bowel cancer in recent years, which suggests we could be over-using this test. This may be due to cases where colonoscopy is over-used to investigate irritable bowel syndrome (IBS) and low iron levels in women, which is usually due to heavy periods and diet.

Other reasons include a fear of missing serious conditions, even if they are unlikely, or because people request to have a colonoscopy although their symptoms do not suggest that it would be helpful.

When is a colonoscopy necessary?

If your parents developed bowel cancer after 70, it is more likely to be age-related. Age alone is not a reason to have a colonoscopy but if you are over 50 and have other symptoms, it is a reason to do it. This includes a change in bowel habits, such as blood in your poo when you go to the toilet, stomach pain and unexplained weight loss. If your ‘poo test’ is positive with blood then you should also have the procedure.


Do not hesitate to book an appointment with Dr Loganayagam if you're over the age of 50 and would like to discuss having a routine colonoscopy. 

By Dr Aathavan Loganayagam

Dr Aathavan Loganayagam trained in medicine at Guy’s, King's and St. Thomas’ medical schools. He then underwent rigorous structured specialty training in gastroenterology and general internal medicine in the well respected South London training programme.

He then spent two years during postgraduate training as a research and endoscopy fellow at Guy’s and St Thomas’ Hospitals, London. His research was in the fields of pharmacogenetics, inflammatory bowel disease and gastrointestinal malignancy. He has received awards and grants for outstanding research work, including the prestigious NHS Innovation London Award.

Dr Loganayagam has numerous publications in peer reviewed journals on all aspects of gastroenterology. He is actively involved in clinical research. He has particular local expertise in the practice of personalised medicine and the utilisation of novel therapeutic agents in the treatment of complex inflammatory bowel disease. He is currently the lead clinician for endoscopy at Queen Elizabeth Hospital, Woolwich.

Diagnostic and advanced therapeutic endoscopy remains a major part of his clinical expertise, including assessment and treatment of inflammatory bowel disease, strictures, polyps and cancers.

Dr Loganayagam is an approachable doctor who takes pride in his communication skills with patients. He is keen to ensure that patients are fully informed and involved in all aspects of their care.

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