Glossary of Irritable Bowel Syndrome Terms

Reviewed by: HU Medical Review Board | Last reviewed: September 2023



The area between the chest and pelvis. It includes the stomach, small intestine, large intestine, colon, liver, gallbladder, and spleen.1,2

Abdominal cramps

Cramps that occur around the stomach and bowels.1

Abdominal pain

Often referred to as a stomachache, abdominal pain refers to pain in the area between the chest and pelvis.1


The process in which nutrients move from the intestines into the bloodstream. The nutrients can then be distributed to all cells in the body for nourishment.1,2

Afferent nerves

Nerve fibers that carry messages from an organ or tissue toward the central nervous system.2

Alarm symptoms

Symptoms including unintended weight loss, bleeding, anemia, and fever that may be a sign something is wrong with the body.3

Anal fissure

A small tear in the tissue that lines the anus. Anal fissures can occur when a person passes hard or large stools.2,3


An exam using a rigid tube to visualize the anus and lower rectum for diagnosis.3


A medicine used to neutralize the effects of acids in the stomach.1

Antidiarrheal drugs

Drugs used to help regulate diarrhea symptoms.1

Antispasmodic drugs

Drugs used to limit the severity of intestinal muscle spasms or cramps.1,2


The lower opening of the digestive tract where feces are discharged.1


A condition where the body’s own tissues are attacked by the immune system.1



Single-cell organisms that can cause disease. Certain bacteria are helpful in the digestive process. Also referred to as germs.1


A chemical element and the main ingredient in barium sulfate. Barium sulfate is used to help the organs in the digestive tract show up on X-ray images or under a fluoroscope.1

Barium enema

A diagnostic procedure where X-rays are taken after the person receives barium sulfate by enema.1

Barium meal

A diagnostic procedure where the person consumes barium sulfate and X-rays are taken afterward.1


A fluid produced by the liver and stored in the gallbladder. This fluid helps digest fats and helps the body discard wastes that do not dissolve in water.1

Bile acids

Weak acids that help to digest fat.1

Bile ducts

A system of tubes that delivers bile from the liver to the gallbladder. The system may also deliver bile to the intestine.1


The feeling of fullness in the abdomen that can occur after eating.1,3

Bristol Stool Form Scale

Classification of feces into 7 groups by how liquid or solid the stool is.1


Calprotectin test

A test used to detect inflammation in the intestines and screen for inflammatory bowel disease.3


A pouch forming the first part of the large intestine. It connects the colon to the ileum.1

Celiac disease

A disease that results from an allergy to gluten. It causes an inability to digest and absorb the protein gliadin, a component of gluten. It is also referred to as celiac sprue and gluten intolerance.1-3

Centrally mediated abdominal pain syndrome (CAPS)

Recurrent abdominal pain that can often be severe. It occurs because of altered sensitivity to nerves in the gut and brain. It has no relation to eating or pooping.3

Chronic idiopathic constipation

Also referred to as functional constipation. It shares similarities in symptoms and treatment with IBS-C. Chronic means ongoing.1

Chronic Nausea Vomiting Syndrome

Nausea that happens at least once per week that can impact usual routines. Chronic means ongoing.3


Surgical procedure to remove part or all of the colon.2


Disease where the colon is inflamed.1,2


The large intestine, which extends from the cecum to the rectum.1


An exam of the colon using an endoscope.1,3


Difficulty passing stool, painful bowel movements, and/or infrequent bowel movements.1,2

Crohn’s disease

An ongoing (chronic) inflammatory disease that can affect any part of the digestive (gastrointestinal or GI) tract, commonly the ileum or colon.1,2

CT (computerized tomography) scanning

The use of X-rays to show 3-D images of a person’s body.1

Cyclic vomiting syndrome

A disorder where there are recurring episodes of nausea and vomiting that can last for a week or more. People do not experience nausea or vomiting between episodes.2,3


Diagnostic imaging

The use of X-ray, ultrasound, or other pictures of the body’s organs to help make a diagnosis.1


A condition where stool is in a more liquid state.1,2

Dietary fiber

Dietary fibers are indigestible, nonstarch materials that are found in the cell walls of plants. Dietary fiber can be found in whole grain items, fresh fruits and vegetables, and nuts.1


The process of breaking down food into substances that can be absorbed by the intestine.1,2

Digestive juices

Acids, enzymes and other chemicals produced by the body to break down food to be absorbed.1

Digestive tract

A group of organs from the mouth to the anus where food is ingested, digested, and expelled.1,2

Disorders of the gut-brain interaction (DGBIs)

Disorders that involve the connection between the digestive system and the brain. These disorders can cause symptoms like visceral hypersensitivity, altered mucosal immune function, altered microbiota, or central dysregulation.1,3


A visible increase in the abdomen.1


A condition where a diverticulum becomes inflamed.1


A condition in which small sacs, diverticula, form in the wall of the colon.1


A small sac that forms in the wall of the colon. The plural form is diverticula.1

Dumping syndrome

When food is emptied too quickly from the stomach.2


The first part of the small intestine.1,2


Pain or discomfort that can occur in the upper abdominal area from the stomach.1


Difficulty swallowing. It may feel like food is stuck in your throat, but without any pain.2,3


Early satiety

The sensation of feeling full without eating a full meal.1


A tube with a light and a lens on the end that allows a doctor to look into the esophagus, stomach, duodenum, small intestine, colon, or rectum.1,2


An inflammation of the small intestine.1,2


A protein that helps break down foods into simpler substances for absorption.1


The organ that connects the mouth to the stomach.2


To discharge waste from the body.1


Fecal elastase

This test, done on stool, helps to find out if the pancreas is properly working by testing for an enzyme that comes from the pancreas.3

Fecal incontinence

Accidental loss of solid or liquid stool, often in children.3


Waste released from the bowels.1


The process of bacteria breaking down substances. In the colon, bacteria breaks down undigested bits of food. This causes the release of hydrogen and carbon dioxide.1


The passage of gas through the rectum. It can be concerning if the frequency, sound, or odor becomes severe.1


Gas passed by the rectum.1


A device using X-rays to examine the inside of organs.1


An acronym representing carbohydrates that share similar features and are not effectively absorbed in people living with IBS. FODMAP stands for fermentable, oligosaccharides, disaccharides, monosaccharides, and polyols.1

Functional disorder

A disorder where the intestinal tract does not properly work despite no visible signs of disease. It is not life threatening.1,2



A sac located beneath the liver that can store about half a pint of bile.1


Solid masses made mostly of cholesterol that form in the gallbladder or bile ducts.1

Gallstone disease (gallbladder disease)

A condition where gallstones are located in the gallbladder.1


Relating to the stomach.1,2

Gastric juices

Liquids produced in the stomach to help digest foods and kill bacteria.1


Inflammation of the stomach lining.1,2

Gastroduodenal disorders

Diseases of the stomach and the duodenum, which is the first part of the small intestine.3


Inflammation of the stomach and the intestine.1,2


A doctor specializing in treating diseases and disorders associated with the digestive system.1,2

Gastroesophageal reflux disease (GERD)

Irritation when the stomach contents leak backward into the esophagus.1


A condition where the contents of the stomach empty more slowly than usual. This can cause more symptoms in the digestive system.1


The process of using a tube passed through a person’s esophagus to examine their stomach.1


A disorder where there is an ongoing but not painful sensation of a lump or foreign body in the throat.3


The most common simple sugar that is present in nature.1


A protein found in certain grains, including wheat, rye, and barley.1

Gut microbiota

The microorganisms that are located in the intestines or gut.3



When veins are dilated around the anus. Symptoms occur when veins become enlarged, prolapsed, plugged, or inflamed.1


Passed genetically from parents to their children.1



Also referred to as IBS-M. Irritable bowel syndrome that may cause gas, bloating, abdominal pain, diarrhea, and constipation.1


Irritable bowel syndrome with constipation as a major symptom.1


Irritable bowel syndrome with diarrhea as a major symptom.1


The part of the small intestine closest to the colon.1,2


When stool becomes hardened and is difficult to release from the body.1


Any disruption in the digestive process. Symptoms can include heartburn, nausea, bloating, and gas.1

Infectious diarrhea (traveler's diarrhea)

Diarrhea caused by a virus, bacteria, or protozoan.1


A condition where the body responds to tissue damage. Common signs of inflammation include redness, heat, swelling, pain, and loss of function.1

Inflammatory bowel disease (IBD)

Disorders causing inflammation in the intestines, including Crohn’s disease and ulcerative colitis.1

Intestinal flora

Bacteria, yeasts, and fungi found normally in the intestines. Another term for this is gut microbiota.1

Intestinal mucosa (intestinal lining)

The lining of the intestines where absorption occurs.1

Irritable bowel syndrome (IBS)

A functional bowel disorder affecting the stomach and intestines. There is ongoing abdominal pain, gas, and/or bloating. The person with IBS may experience constipation and diarrhea.1,3



A complex sugar needed to be broken down into galactose and glucose for absorption. It is found in milk and milk products.1

Lactose intolerance

A condition where a person's body does not make enough lactase to digest lactose. Common symptoms include abdominal cramping and diarrhea after eating or drinking products with lactose, such as milk and cheese.1

Large intestine

The part of the intestinal tract that goes from the small intestine to the anus. The large intestine includes the appendix, cecum, colon (ascending, transverse, descending, and sigmoid), rectum, and anus.1

Lower GI series

An X-ray that uses barium to show visuals of the large intestine. Also referred to as a barium enema X-ray. GI stands for gastrointestinal.1



A condition where the intestine has difficulty digesting or absorbing food. Malabsorption can result in gas or diarrhea. It also limits the amount of nutrients the body can get from food.1


The movements of the intestines in the body.1

Motility disturbance

Disorders due to abnormal movement in the bowels.3


Discharge made by the intestines, protecting tissue in the digestive (gastrointestinal or GI) tract.1



A feeling of the need to vomit.3

Nocturnal pain

Pain that is felt at night.1



Blockage that prevents the flow of liquids or solids, resulting in pressure buildup.1


A disorder of thinking where a person has the idea that certain foods can result in negative side effects. This leads the person to avoid those foods.3


Pancreaticobiliary disease

Disorders that affect the gallbladder, biliary ducts, and pancreas.3

Pelvic floor

A group of muscles that support the pelvic organs and are involved in urination and pooping.2,3


Relaxation of the muscles of the intestine that results in movements that push the contents forward through the digestive (gastrointestinal or GI) tract.1,3


The inflammation of the lining of the rectum.1


A doctor specializing in the treatment of disorders relating to the anus and rectum.1



The lower end of the large intestine that leads to the anus.1


The flow of food from the stomach back to the mouth.1



The feeling of being full after eating.3

Small intestinal bacterial overgrowth (SIBO)

Uncontrolled amounts of gut bacteria in the small intestine.1


An endoscope used to examine the anus, rectum, and sigmoid colon.1

Small bowel enema

A procedure where a tube is passed through the nose or mouth into the small intestine. Barium liquid is inserted in the tube and examined as it passes through the small intestine.1

Small bowel follow-through

A procedure that examines the small intestine using X-rays as barium liquid passes through it.1

Small intestine

The longest part of the digestive tube, which connects the stomach and the large intestine. This is where most digestion and food absorption happens. The small intestine includes the duodenum, jejunum, and ileum.1


The matter discharged from the anus.1



An open sore on the surface of the skin or on the lining of the stomach.1

Ulcerative colitis

An ongoing (chronic) inflammatory disease of the lining of the large intestine.1

Ultrasound imaging

A test where sound pulses are sent into the body to produce visual images.1

Upper GI series (barium meal)

A procedure where X-rays show the esophagus, stomach, and duodenum. GI stands for gastrointestinal.1,2


Vagus nerve

The main nerve of the parasympathetic nervous system. The vagal nerves play an important role in digestion, including the production of stomach acid.1


Finger-like projections that help absorb nutrients in the intestines.2


Vomiting is the release of digestive (gastrointestinal or GI) contents. Nausea often happens along with vomiting.3

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