abscess – localised collection of pus within a tissue

ACTH response – a measure of adrenal impairment

acute toxic megacolon – distension of the colon with paralysis and loss of ability to absorb water and electrolytes – potentially fatal

aphthous ulcers – shallow, painful areas of damaged mucosa in CD patients

auto-antibodies – antibodies which attack their own body cells

autoimmune disease – a condition in which cells of the body are attacked by its own immune system

biopsy – small sample of tissue for microscopic analysis

cataracts – opaque tissue forming in the eye, affecting sight

chronic intermittent UC – long-term UC, with periods of remission between acute flare-ups

cirrhosis – chronic liver disorder in which fibrous scar tissue gradually replaces normal liver tissue

clubbing – thickening of the bones of the fingertips and toes

colonoscope – flexible fibre-optic (endoscope) speculum used to examine the colon internally

colonoscopy. This involves inserting an endoscope into the colon to view the mucosal surface directly and to take tissue samples for analysis if required

colorectal – the area of the colon adjoining the rectum

complication – a condition occurring during the course of or as a result of another disease and often aggravating it

confluent ulceration – ulcers that have joined up to cover large areas

crypt abscess – a deep cleft in the colon wall that fills with inflammatory cells, bacteria and cell debris (i.e. pus) as a result of UC

deep venous thrombosis – a blood clot that forms in and blocks one of the deep veins

disease progression – the gradual worsening of a disease

distal – far from the centre of the body e.g fingers are on the distal end of the arm

distal colitis – inflammation of the rectal end of the colon

distension – swelling or dilation of a hollow organ or body cavity due to internal pressure

diverticular disease - formation of sacs or pouches of mucosal tissue through the intestinal wall

dyscrasias – blood disorders that can be a rare adverse effect of treatment with mesalazine or balsalazine

dysplasia – abnormal development of tissues, organs or cells

endoscope – an instrument for viewing the interior of a bodily canal or hollow organ

endoscopy – the use of an endoscope in a body cavity such as the alimentary canal

enema – the injection or insertion of liquid into the rectum for cleansing, laxative or other therapeutic purposes

enteral nutrition – nutrients delivered via the alimentary canal

enteric pathogens – micro-organisms causing infections in the alimentary canal

episcleritis – painful inflammation of the external eye tissues

fibrotic – the stiff, fibrous structure of affected parts of the bowel wall in CD

fistulas – abnormal communication between a hollow organ and its surface

friable – fragile, easily damaged, crumbly

glaucoma – raised intraocular pressure that can cause blindness

granulomas – lumps formed from clumps or aggregates of inflammatory cells

haemorrhage – sudden flow of blood from damaged blood vessels

haemorrhagic lesions – bleeding defects in the mucosa of CD patients

infectious colitis – inflammation of the colon due to infection by a pathogenic organism

infiltration – gradual entry of cells or substances into a body tissue

insufflated – air or other gas or vapour blown into a body cavity

ischaemic colitis – inflammation of the colon due to localised loss of blood supply causing tissue damage

malignancy – an abnormal growth threatening health and/or life – often spreads or metastasizes to other parts of the body

metastatic Crohn’s disease ulcerated areas of skin appearing on patients with CD

microbiological culture – a process used to detect and identify micro-organisms

mucosal islands – raised, red, swollen patches of mucosa left on an otherwise ulcerated area of the intestinal wall

nasogastric tube – a thin tube inserted through the nasal passages, down the oesophagus and into the stomach or duodenum

necrosis – death of living tissue due to disease, injury or interruption of blood supply

nephrotoxicity – toxic effects occurring within the kidney

neurotoxicity – drug-induced damage to peripheral nerves

osteoblasts – cells involved in forming and replacing bone

osteocytes – cells involved in the removal or replacement of bone

osteoporosis – brittleness and weakening of bone due to old age or as a side effect of steroid treatment

parenteral nutrition – nutrients delivered by any route except the alimentary canal

percutaneous – through the skin

peritonitis – infection of the intra-abdominal space

hypothalamus – pituitary – adrenal (HPA) axis interaction between these glands controls

prophylaxis (prophylactic treatment) – preventive treatment, taken to stop symptoms developing – as opposed to standard treatment of symptoms as they occur

prostration – inability to stand up due to muscular weakness caused by illness

proximal – near to the centre of the body (opposite to distal)

pus – a fluid containing bacteria and inflammatory cells plus cell debris - associated with infection and inflammation

pyrogens – temperature-raising chemicals released by inflammatory cells

radiation colitis – inflammation of the colon due to exposure to radiation – usually as part of cancer treatment

radiology – the use of X-rays in medical diagnosis or ionising radiation in radiotherapy or diagnosis

short bowel syndrome – potentially fatal condition due to removal of too much small intestine, causing inability to digest food adequately

sonography – use of sound to form images e.g ultrasound scanning

splenic flexure – the junction of the transverse and descending colon near the spleen

stoma – a surgically constructed alternative external exit point for faeces

stricture – a narrowing or restriction in a tube such as the alimentary canal

suppositories – solid drug dosage forms, shaped for insertion into the rectum

suppurating – forming and/or discharging pus

tenesmus – painful, difficult defecation with pellet-like stools in UC

total parenteral nutrition – provides all the nutrients needed by severely ill patients, bypassing the alimentary canal

ulcer – an inflammatory, often suppurating lesion on the skin or internal mucus membrane, causing tissue necrosis and usually taking a long time to heal

ultrasound – sound frequencies above 20 kHz, the upper limit for human hearing – used in sonography to visualise internal tissues

uveitis – sight-threatening inflammation of the iris and associated structures