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Gastrointestinal disease

Gastrointestinal disease

Disease involving the gastrointestinal tract


Gastrointestinal diseases are diseases in the gastrointestinal (GI) tract, from the mouth to the anus. Gastrointestinal diseases are categorized as functional or structural. Structural types of gastrointestinal diseases have identifiable abnormalities in the appearance of the GI tract. Functional gastrointestinal diseases are those in which the GI tract has abnormal motility while having a normal appearance upon examination. Functional gastrointestinal diseases are more common than structural gastrointestinal diseases, those in which the appearance of the GI tract is abnormal.

Examples of functional gastrointestinal diseases are constipation, irritable bowel syndrome (IBS), nausea, food poisoning, gas, bloating, gastroesophageal reflux disease (GERD), and diarrhea. The GI tract and its mobility may be affected by the following: low fiber diet, lack of exercise, traveling, consuming large amounts of dairy, stress, resisting bowel movements, overuse of anti-diarrheal medications, certain medications and pregnancy.

Examples of structural gastrointestinal diseases are strictures, stenosis, hemorrhoids, diverticular disease, colon polyps, colon cancer, and inflammatory bowel disease.

Irritable bowel syndrome (IBS)

Irritable bowel syndrome (IBS), also called spastic colon, irritable colon, or nervous stomach, is a functional gastrointestinal disease. In IBS the colon muscle contracts more often or less often than normal and this can be triggered by certain foods, medicines, and emotional stress. Symptoms of IBS include abdominal pain and cramps, excess gas, bloating, change in bowel habits, and alternating constipation and diarrhea. IBS may be treated with the following: avoiding excessive caffeine, increasing dietary fiber, monitoring and avoiding certain foods, minimizing stress or finding ways to cope with stress, avoiding dehydration, and getting quality rest and sleep. Medications for IBS may be prescribed by a healthcare provider.

Inflammatory bowel disease (IBD)

Inflammatory bowel disease (IBD) is an umbrella term for disorders with chronic inflammation in the GI tract. IBD may be confused with IBS but the two are distinct conditions. Unlike IBS, IBD involves inflammation that is destructive and causes permanent damage to the intestines. Diagnostic imaging shows abnormal bowel appearance in IBD and the disease carries an increased risk for colon cancer. Ulcerative colitis and Crohn’s disease are types of IBD. Both of these conditions can present with symptoms such as diarrhea, rectal bleeding, abdominal pain, fatigue, reduced appetite, and weight loss. IBD symptoms can range from mild to severe and can have periods of active illness and remission. Complications in common for both ulcerative colitis and Crohn’s disease include increased risk of colon cancer, inflammation of the skin, eye and joints, liver damage (primary sclerosing cholangitis), blood clots and medication side effects.

The cause of IBD is not known but thought to involve a malfunction of the immune system where the immune system has an abnormal response to pathogens and mistakenly attacks cells in the digestive tract. IBD was previously thought to be caused by diet and stress but now these are now thought to be aggravating factors rather than the cause. IBD is more common in people with family members with the disease, suggesting some hereditary component, but most people with IBD do not have a family history.

Ulcerative colitis

Ulcerative colitis is a type of IBD affecting the superficial lining of the large intestine and rectum and is characterized by inflammation and sores or ulcers. Complications of ulcerative colitis may include toxic megacolon, perforated colon, and severe dehydration.

Crohn’s disease

Crohn’s disease is a type of IBD involving inflammation that affects deeper layers of the digestive tract compared with ulcerative colitis. Complications of Crohn’s disease include bowel obstruction, malnutrition, fistulas, and anal fissure.

Diagnostic tests
Upper GI tract
Upper GI Series

An Upper GI Series is a series of X-rays of the upper digestive tract taken while the patient drinks a mixture of barium and water. The mixture is delivered either as a barium swallow or a barium meal, which coats the walls of the digestive tract and helps the healthcare team see abnormalities. A barium swallow will allow visualization of the esophagus and upper stomach. A barium meal will be followed as it travels through the esophagus, stomach, and upper part of the small intestine.


Gastoscopy is the insertion of a small camera attached to an endoscope, used for suspected upper GI illnesses such Crohn’s disease, GERD, gastric ulcers, hiatus hernia, celiac disease, and some cancers.

Endoscopic retrograde cholangiopancreatography (ERCP)

ERCP is an exam with both endoscopy and X-ray components used to examine bile and pancreas ducts for suspected pancreatitis, gallbladder disease, and tumors of the bile ducts or pancreas.

Endoscopic ultrasound

Endoscopic ultrasound may be used as an alternative to ERCP to diagnose physical problems in the esophagus, stomach, pancreas, gallbladder, and liver.

pH monitoring

Signs of stomach acid in the esophagus are detected by pH monitoring for diseases such as GERD. Monitoring of pH can determine severity of symptoms and monitor effectiveness of acid suppression or antacid therapy.

Esophageal and gastric manometry

Esophageal manometry and gastric manometry tests examine movement and pressure in the esophagus and stomach, respectively. The procedure is performed for symptoms such as heartburn, difficulty swallowing and painful swallowing. Gastric manometry may be performed for suspected gastric-emptying disorders.

Liver biopsy

For a liver biopsy a needle is inserted with ultrasound guidance to collect the biopsy for diagnoses of liver disease such as non-alcoholic fatty liver disease, fibrosis, and cirrhosis.

Lower GI tract

A colonoscopy is performed with a colonoscope inserted into the rectum while under conscious sedation. Colonoscopies are used for conditions such as Crohn’s disease and cancer and biopsies can be taken during the procedure.

Barium Enema

A barium enema is also called a lower GI series or colon X-ray. The procedure involves the administration of an enema containing barium followed by X-ray imaging.

Flexible Sigmoidoscopy

Flexible sigmoidoscopy is the insertion of a flexible tube-like device with a light and a camera called a sigmoidoscope into the colon. This procedure is used for only the lower-most section of the colon called the sigmoid and may include taking a biopsy. Conscious sedation is not used for this procedure.

Virtual colonoscopy

A virtual colonoscopy is performed with a tube inserted into the rectum that fills the bowel with air. A computerized tomographic (CT) scan will produce images that will construct a 3-dimensional view of the intestine. The procedure is used to check for cancers or malignant polyps.

Capsule endoscopy

Capsule endoscopy is used to detect illness in any area of the digestive tract. A pill containing a tiny video camera, a light, batteries, and a radio transmitter is swallowed. Images are taken and wirelessly transmitted to a recording device attached to the patient’s waist.

Anorectal manometry

Anorectal manometry is a test of the health and strength of gastrointestinal muscles. The test is used to analyze the strength of the anal sphincter muscles in cases of fecal incontinence.

Non-invasive imaging
Magnetic resonance imaging (MRI)

MRI uses radio waves and magnets to generate images for diagnosis of gastrointestinal diseases and abdominal problems.


Ultrasound imaging uses sound waves create an image of internal organs. Ultrasound can visualize swelling or damage due to GI illnesses such as pancreatitis and Crohn’s disease. A fibroscan uses ultrasound waves to measure liver thickness in order to stage fibrosis arising from conditions such as hepatitis B, hepatitis C, and non-alcoholic fatty liver disease.

Fecal tests
  • Fecal calprotectin tests detect elevation of calprotectin, which is found in people experiencing inflammation
  • Fecal occult blood tests are used for gastrointestinal conditions that cause bleeding
  • Fecal immunochemical tests (FIT) are indicated for detection of blood in stool for colorectal cancer screening
  • Fecal lactoferrin is a marker for intestinal inflammation in IBD
At home fecal monitoring for IBD

Calprotectin is excreted in the feces when there is inflammation in the intestines. Calprotectin levels may be monitored in IBD or may be used to distinguish between IBD and IBS.

  • CalproSmart Home (Calpro) for patients with established IBD such as ulcerative colitis and Crohn’s disease
  • QuantOnCal product and app
  • IBDoc (Buhlmann laboratories) product and app
  • Actim Calprotectin
Blood tests for IBS and IBD
  • IsolateIBS-IBD (Analyte Health and IQuity Inc.) analyses RNA in blood
  • Blood testing for white blood cells or low red blood cell count to test for inflammation and anemia respectively may be used for Crohn’s disease
  • C-reactive protein (CRP) is a marker of inflammation elevated in IBD
  • Erythrocyte sedimentation rate (ESR) measures how quickly red blood cells settle and is an indirect measure of inflammation used for IBD
  • Albumin is an inflammatory marker
  • Transaminases is an inflammatory marker
  • Gamma-glutamyl transferase (yGT) is an inflammatory marker
At home fecal tests for colorectal cancer
  • Self-Sure (Epitope Diagnostics)
  • Fobcheck (NanoRepro)
  • Certain Bowel Health Test (Koroglu Medical Devices)
  • SELFCheck: Bowel Health Kit (CARE Diagnostica)
  • Bowel Home Test Kit (The Boots Company)
  • Prima Home Test: Bowel Test – FOB (Healthy Europe s.r.l.)
Lactose intolerance tests

Hydrogen breath test: for diagnosing lactose intolerance by detecting undigested sugars in the breath.

Lactose tolerance test: measures blood sugar levels after consuming lactose and individuals who are lactose intolerant do not absorb all of the lactose.

Stool acidity test: for diagnosing lactose intolerance which can be suggested by specific levels of acid and other by-products in stool.

Helicobacter pylori (H. pylori) breath test

An H. pylori breath test detects H. pylori bacteria, which can cause ulcers.

At home blood tests for celiac disease
  • Tissue transglutaminase (tTG) antibodies are detected in blood sample obtained by pinprick
  • Endomysial antibody (EMA) test detected in blood sample obtained by pinprick
Clinical management software

Crohn’s Colitis Care (CCCare) is a cloud-based clinical management software developed by the Australia and New Zealand Inflammatory Bowel Disease Consortium of clinicians and software developers. The product collects patient-reported disease activity and medical assessment, monitors medications, screens for cancer, provides preventative health, and facilitates communication with the IBD team and referring doctor.


The Human Microbiome Project (HMP) is established by the NIH to characterize the gut microbiome, including alterations in IBD.
The IBD Genetics Consortium (IBDGC) is established by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) to identify genes involved in IBD susceptibility.
September 12, 1967
The National Foundation for Ileitis and Colitis is founded by the Suzanne and Irwin Rosenthal, Shelby and Michael Modell, and Dr. Henry Janowitz to increase patient education, patient support, and fund research.
Crohn's disease was disease was first described by Burrill Crohn, Leon Ginzberg, and Gordon D. Oppenheimer.

Further Resources


Intestinal Stem Cells to Advance Drug Development, Precision, and Regenerative Medicine: A Paradigm Shift in Translational Research - The AAPS Journal


December 12, 2017

Redefining the IBDs using genome-scale molecular phenotyping

Terrence S. Furey

Journal article



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