Skip to main content


A handy A-Z of medical terms related to colorectal conditions and their meaning.


  1. Stomach: Stores and breaks down the food into a liquid mixture before slowly releasing it into the small bowel (3).
  2. Pancreas: Produces enzymes (substances that speed up chemical reactions) that help the body digest fats, proteins and carbohydrates (starchy foods).
  3. Small bowel: Breaks the food down even further, absorbing the nutrients into the body. Undigested waste moves into the colon (6a).
  4. Liver: Produces bile, which helps the body absorb fat from food.
  5. Gallbladder: Stores bile until the body needs it.
  6. Large bowel: made up of the colon (6a) and rectum (6b). The body absorbs water from the undigested waste as it moves along the colon towards the rectum. Waste is stored in the rectum until it passes out of the body
  7. Anus: This is part of your bottom from where faeces (bowel motion) emerge.
  8. Anal sphincter: This is the muscle around your bottom, which ensures that you are able to control your bowel motion.
Anal abscess

Anal abscesses are collections of pus that occur around the anus. They have different names including perianal abscess, ischioanal abscess and ischirectal abscess. These are extremely common. They can be very painful. Anal abscesses rarely respond to antibiotics and require incision (cut) and drainage of the pus under general anaesthetic (put to sleep).

Anal cancer

Anal cancer is a rare skin cancer that affects the anus. Most anal cancers can be treated without the need for radical surgery.

Anal fissure

This is a split in the lining of the anus, which results in intense pain on defecation and bright red rectal bleeding.

Anterior resection

A major surgical operation to remove the rectum, usually performed for rectal cancer.

Barium enema

An x-ray investigation whereby, having cleared the bowel out with a strong laxative, barium is squirted through the anus, around the bowel and x-rays are taken. This test is very useful for diagnosing structural diseases of the large bowel.

Botulinum toxin

This is a very powerful drug, which relaxes muscles. As well as being used for cosmetic purposes, it is also used to relax the anal sphincter for patients who have anal fissures.

Bowel cancer

Bowel cancer affects about 1 in 30 patients. If it is caught early it can be treated and cured by surgery. Cancer occurs when the cells that line the colon become damaged and begin to divide in an uncontrolled way. This may lead to the formation of a benign growth and eventually a cancer.

Bowel cancer screening

The NHS Bowel Cancer Screening Programme offers screening every two years to all men and women aged 60 to74. Those over 74 can request a screening kit from the programme. The Screening Programme changes from time to time, as more research is undertaken, leading to tests being refined and changes to the types of tests and the ages at which those tests should be undertaken. The aim is to pick up any cancer in its very earliest stages.


This is an operation where part of the large bowel (colon) is removed.


An inflammation of the large bowel characterised by diarrhoea and the passing of dark blood. There are many causes of colitis; most of them can be treated by medication and only rarely is surgery indicated.


This is a very sensitive test for looking at the lining of the large bowel. Prior to the test the bowel needs to be purged by a strong laxative and then a camera is passed from the anus through the whole of the large bowel to where it joins the small bowel. This test can be uncomfortable and is usually performed using a relaxing drug.


The investigation, diagnosis and treatment of all aspects of colorectal conditions, including problems with your colon, bowel, rectum and appendix.

Colorectal cancer

See Bowel cancer


This is a surgical operation whereby a piece of large bowel is brought onto the tummy wall. Faeces (bowel motion) pass through the abdominal (tummy) wall where it is collected into a bag (pouch).

Crohn’s disease

This is a form of inflammatory bowel disease, which can affect the whole of the bowel from mouth to anus. It can usually be controlled by medication but occasionally surgery is necessary, if the inflammation becomes very severe.

CT colonography

This is a specialised type of CT, which enables diseases of the large bowel to be identified. It requires bowel preparation but is less invasive than a barium enema or a colonoscopy.

CT scan

This is a highly sophisticated type of x ray that provides a three-dimension reconstruction of your internal organs.


This is the loss of loose/liquid stool on a frequent basis; often every few hours. It can be accompanied by colicky abdominal pain.

Diverticular disease (diverticulitis)

This affects the large bowel, most often the sigmoid colon. Characterised by ‘pockets’ in the wall of the bowel, which can give a variety of symptoms such as pain, diarrhoea and constipation. It is common as one gets older and rarely requires surgery.

Faecal incontinence

This is the uncontrollable loss of wind, liquid or solid stool from the back passage.

Flexible sigmoidoscopy

This is a telescope test that inspects the left hand side of your bowel. Bowel preparation is required to clear faeces (bowel motion) prior to the test. The telescope is flexible and requires the surgeon to blow some air into the back passage to enable good views of the lining of the bowel.


Also known as piles, these are fleshy skin cushions around the anus, which are responsible for anal soreness, bright red rectal bleeding and mucus discharge.


Conditions that cause inflammation of the intestines, such as Crohn’s disease or ulcerative colitis, are known as inflammatory bowel disease (IBD). This shouldn’t be confused with irritable bowel syndrome (IBS) which is a different condition and requires different non-surgical treatment. However, some people with IBD can also have IBS.


This is a surgical operation whereby a piece of small bowel is brought onto the tummy wall. Bowel contents pass through the abdominal (tummy) wall where it is collected into a bag (pouch)


This is a clear, jelly like substance that is often lost from the anus. It is associated with large haemorrhoids and/or constipation.

Perianal haematoma

This is a small blood clot, which occurs under the skin near the anal verge. It is often associated with haemorrhoids and constipation. It can be extremely painful and may require surgical drainage.


See Haemorrhoids.


These are benign growths of the large bowel, which are extremely common. We believe that about 1 in 10 polyps, greater than 1cm, if left long enough within the bowel, will turn into cancer.


This is inflammation of the rectum and can be due to many causes. It often responds to the use of suppositories.


This is a procedure where a 6cm tube is inserted into your anus to allow inspection of your anal canal. It is used for diagnosing anal problems such as fissures or haemorrhoids.

Pruritus ani (itchy bottom)

The causes for itchy bottom are many, majority of which will settle. Piles, prolapse of the rectum, chronic diarrhoea and infections are amongst some of the reasons. It is important to report the symptom to your doctor if it is not resolving quickly as rarely it could be an early sign of cancer around the back passage and anal canal.

Rectal prolapse

This is a condition whereby the rectum protrudes outside the anus, especially when opening one’s bowels.

Rigid sigmoidoscopy

This is a test, often performed at the initial out-patient consultation. It involves the passing of a long tube through the back passage to allow the doctor to look at the lining of your rectum. A small amount of air is blown in at the time to allow the rectum to distend.

Rubber band ligation

This is a simple out patient treatment for larger internal piles. Occasionally, it can cause discomfort around the back passage. This normally disappears within 48 hours. It can result in some bright red rectal bleeding when the bands drop off within 10 days after the procedure.

Transanal endoscopic microsurgery (TEM)

TEM is a technique to remove polyps and small rectal cancers by local excision (removal). This avoids the need for a radical excision (anterior resection) and possibly the need for a stoma.