Medical Terms


Abdomen –  the part of the body containing the digestive organs, including the stomach, small intestine, large intestine (including the colon), pancreas, liver and gall bladder.

Abscess – a pus-filled area that becomes red, swollen and painful, usually in response to an infection. In people with Crohn’s, abscesses may form in the abdomen or in the anal and rectal area. 

Amenorrhoea – an abnormal absence of menstruation.

Aminosalicylates – (5-ASAs) – a type of drug used to reduce inflammation and decrease the risk of relapse in Crohn’s and Colitis. Types include balsalazide, mesalazine, olsalazine and sulphasalazine.

Anaemia – reduced numbers of red blood cells.  Red blood cells carry oxygen around the body.  Lack of red blood cells can cause tiredness and shortness of breath. In IBD, anaemia may be due to blood loss and/or poor intake or absorption of vitamins or iron. 

Anti-Müllerian hormone (AMH) – A hormone made by the ovaries in females and the testicles in males. 


Biopsy – a small piece of tissue taken from the body for examination under a microscope. These are often taken during colonoscopies to diagnose IBD.

Biosimilars – a biologic drug that is highly similar to another approved biologic medicine, but manufactured by a different company.

Biologic – a type of drug that can be used to treat IBD. See anti-TNF drugsvedolizumab and ustekinumab.


Calcium – a mineral needed for healthy teeth, bones, and other body tissues. 

Colectomy – surgical removal of the colon.

Colon – the part of the large intestine that absorbs water from undigested food waste to form a normal stool. 

Colonoscopy – an examination of the rectum, colon and last part of the small intestine (terminal ileum) using a narrow tube with a camera in its tip, sometimes called a colonoscope, which is inserted through the anus.


Digestive system – The organs that take in food and liquids and break them down into substances that the body can use for energy, growth, and tissue repair.

Diarrhoea – frequent and often urgent passing of loose or watery stools. It is usually defined as passing such stools 3 or more times a day.


Endoscopy – a general term for the examination of the inside of the body using a tube with a camera in its tip, called an endoscope, which is inserted through the mouth or anus. The endoscopist carrying out the examination is a specially trained physician, surgeon or nurse. (See gastroscopy, colonoscopy and sigmoidoscopy.)


Faecal calprotectin – specific proteins found in the stools (faeces). Increased levels of these proteins can be a sign of active inflammation. A faecal calprotectin test is a simple stool test recommended for distinguishing between inflammatory bowel diseases, such as Crohn’s disease and ulcerative colitis, and non-inflammatory bowel diseases, such as irritable bowel syndrome.

Fistula – an abnormal channel  connecting two loops of intestine, or the intestine to the skin or another organ such as the bladder or vagina

Flare – a relapse or exacerbation of a medical condition in which symptoms are more troublesome. IBD often involves periods of remission, in which symptoms are mild or unnoticeable, and periods of active inflammation and symptoms referred to as flare-ups.


Ileostomy – a surgical opening where the ileum is brought through the abdominal wall to create an opening called a stoma. Digestive waste is then collected in a bag, which is fitted over this opening and attached to the skin. An ileostomy may be temporary or permanent.

ileal pouch anal anastomosis (IPAA) – see J pouch

Immune system – A complex network of cells, tissues, organs, and the substances they make that helps the body fight infections and other diseases.

intravenous – into or within a vein


J pouch – also known as ileal pouch anal anastomosis (IPAA), is a type of surgical procedure that allows you to eliminate waste normally after the removal of your entire large intestine (colon and rectum).


laparoscopic – a type of keyhole surgery performed in the abdominal (belly) area that allows a surgeon access without having to make large incisions in the skin. 

listeria – bacteria that causes a serious infection, usually caused by eating food contaminated with the bacteria. 

Large intestine/bowel – The long, tube-like organ that is connected to the small intestine at one end and the anus at the other.


Microbiome – The collection of all the microorganisms and viruses that live in a given environment, including the human body or part of the body, such as the digestive system.

Mucus – a white jelly-like fluid produced by the mucosa (the lining of the intestines). People with Ulcerative Colitis may have a lot of mucus in their stools.

Molecule – a group of atoms bonded together, representing the smallest unit of a substance


Osteoporosis – thinning of the bones that may cause weakness and higher risk of fractures.  It is more common in IBD than in the general population, and may be caused by long-term use of corticosteroids, severe active disease or by low levels of oestrogen (female sex hormones). Osteopenia is a mild weakness or thinning of the bones, which is not as severe as osteoporosis.

Ostomy – an artificial opening of the intestine onto the wall of the abdomen (see stoma).


Pelvis – the area of the body below the abdomen that is located between the hip bones and contains the bladder and rectum.


Remission – a period of good health, free of active disease, with few or no symptoms.


Salmonella – bacteria that causes a serious infection, usually caused by eating food contaminated with the bacteria. 

Sigmoidoscopy – an examination of the rectum and the lower colon using a short tube with a camera in its tip, called a sigmoidoscope, inserted through the anus.

Small intestine/bowel – the section of the intestines that digests food and absorbs nutrients after they have passed through the stomach. The small intestine is divided into three parts: the upper region – called the duodenum; the middle region – the jejunum; and the lower region – the ileum.

Stoma – a surgically constructed opening of the intestine onto the abdominal wall, over which a bag can be fitted and sealed to the skin for waste matter to drain into.

Stool – another words for faeces.

Stricture – a narrowing of a section of the bowel due to bowel wall thickening, inflammation or scarring.


Ulcers – an open sore on external or internal tissues of the body.


Vitamin D – a vitamin produced by the action of sunlight on our skin that is essential for bone health. IBD can sometimes lead to a deficiency of vitamin D, and supplements are sometimes necessary.