Plain-language medical glossary
Content date: 10 November 2026
Short explanations of terms you may hear in the clinic or read in your results. Select a term within a topic to open its explanation here.
Biopsy
A small sample of tissue from an organ that a pathologist (a doctor who examines tissue) examines under a microscope. It may help diagnose inflammation or other conditions. Having a biopsy does not necessarily mean cancer is suspected. Depending on the organ, the sample may be taken during endoscopy or with a needle.
Remission (inactive disease)
A period when disease activity settles. Clinical remission means symptoms of active disease are absent or minimal according to your doctor’s assessment. Some improvement alone does not necessarily mean remission. Few symptoms do not prove inflammation has gone; stool and blood tests or endoscopy may be needed. Remission does not mean you should stop maintenance treatment on your own.
Ascites
Fluid collecting in the abdominal cavity, rather than simply gas. Liver disease and other conditions can cause it. Fever or abdominal pain in someone with ascites needs urgent assessment because the fluid may be infected.
Varices
In liver disease, this usually means enlarged veins in the esophagus or stomach caused by increased pressure in the portal vein. They are different from varicose veins in the legs. Vomiting blood or passing black, tarry stools requires emergency care, even without dizziness.
AFP — alpha-fetoprotein
A blood test measuring the protein alpha-fetoprotein. It is used with imaging to check for tumors in some people with liver disease. Non-cancerous conditions can also raise it, and a normal result does not rule out a tumor. The test alone cannot diagnose cancer. It has a different use during pregnancy.
PCR — testing genetic material
A laboratory technique that detects genetic material. When monitoring viruses, it may detect HBV DNA or HCV RNA and measure viral load, depending on the test. It is different from an antibody test. “Undetectable” means the level is below the test’s detection limit in that sample; it does not always mean a permanent cure or complete absence of the virus from the body.
Liver fibrosis and cirrhosis
Fibrosis means scar tissue following liver injury. In the F0–F4 system, F0 means no fibrosis; F1 is mild, F2 moderate and F3 advanced fibrosis; F4 is cirrhosis, with altered liver structure. F1–F3 can regress with treatment of the cause, especially earlier stages, but improvement is not guaranteed. F4 can also improve, without necessarily restoring a normal liver. Follow-up and prescribed surveillance remain important. Liver stiffness is a measurement, not a diagnosis or proof of an exact fibrosis stage.
ERCP — bile and pancreatic duct endoscopy
A procedure combining a scope passed through the mouth with X-rays to access the bile or pancreatic ducts. It is mainly used for treatment, such as removing a stone or placing a stent, and differs from routine gastroscopy.
MRCP — MRI of the bile and pancreatic ducts
An MRI examination showing the bile and pancreatic ducts without inserting a scope into them. It helps assess stones and narrowing, but cannot remove stones or place a stent. Tell the imaging team about implanted devices or metal.
Ferritin — iron stores
Ferritin is a protein that stores iron. A low level may indicate depleted stores, but a high result can occur with inflammation or liver disease and does not by itself prove iron overload. It is interpreted with other tests.
Transferrin saturation (TSAT)
Transferrin carries iron in the blood. This test estimates how much of its iron-carrying capacity is being used. Alongside ferritin, it helps assess iron deficiency or overload; one result is not a diagnosis on its own.
INR — a blood-clotting test
A result calculated from a test of how long a blood sample takes to clot. It is used to monitor warfarin and may contribute to liver assessment. Medicines and other factors affect it; do not adjust blood thinners yourself.
Biologic treatment
A complex medicine produced using living cells or systems. Many IBD biologics target particular inflammatory signals or cells. Administration, monitoring and storage differ between medicines; follow your own prescription and medicine card.
Biosimilar medicine
An approved biologic with no clinically meaningful difference in safety or effectiveness from its reference medicine. Packaging, injection devices or storage instructions can differ. Follow the instructions for the product dispensed to you.
Fecal calprotectin
A protein measured in stool to help assess bowel inflammation and treatment response. Other conditions can also raise it. Your doctor interprets it with symptoms and other tests; a single result is not enough to diagnose disease or change treatment.
Stricture
A narrowed area that may limit the passage of food or fluid. Inflammation, scarring and other causes need different treatments. Severe pain with swelling, vomiting or inability to pass gas needs urgent assessment.
Fistula
An abnormal channel between the bowel and another organ or the skin. It differs from a fissure, a small tear, and an abscess, a collection of pus. A fistula can coexist with an abscess; increasing pain or fever needs prompt assessment.
Portal vein
A large vein that brings blood from the digestive tract to the liver. Raised pressure here can contribute to varices and ascites. Portal pressure is different from the blood pressure measured with a cuff on your arm.
Stent
A small tube placed in a narrowed duct or passage to help fluid or food pass. Some stents are temporary and need removal or replacement. Obtain a written follow-up date; feeling better does not mean the stent can be forgotten.
Hepatic encephalopathy
Liver disease can allow substances to affect brain function, causing confusion, altered sleep or drowsiness. New confusion or unusual difficulty waking needs urgent assessment; do not assume it is ordinary tiredness.