Gastroenterology (from the Greek gastḗr- "belly", -énteron "intestine", and -logía "study of") is the branch of medicine focused on the digestive system and its disorders.
The digestive system functions to move material through the GI tract via peristalsis, break down that material via digestion, absorb nutrients for use throughout the body, and remove waste from the body via defecation.
Some of the most common conditions managed by gastroenterologists include gastroesophageal reflux disease, gastrointestinal bleeding, irritable bowel syndrome, inflammatory bowel disease (IBD) which includes Crohn's disease and ulcerative colitis, peptic ulcer disease, gallbladder and biliary tract disease, hepatitis, pancreatitis, colitis, colon polyps and cancer, nutritional problems, and many more.
History
Citing from
Ancient Egypt papyrus, John F. Nunn identified significant knowledge of gastrointestinal diseases among practicing physicians during the periods of the
.
Irynakhty, of the tenth dynasty, 2125 B.C., was a
court physician specializing in gastroenterology, sleeping, and
proctology.
[Nunn JF. Ancient Egyptian Medicine. 2002. .]
Among ancient Greece, Hippocrates attributed digestion to concoction. Galen's concept of the stomach having four faculties was widely accepted up to modernity in the seventeenth century.
18th century
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Italy Lazzaro Spallanzani (1729–99) was among early to disregard Galen's theories, and in 1780 he gave experimental proof on the action of gastric juice on foodstuffs.
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In 1767, Germany Johann von Zimmermann wrote an important work on dysentery.
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In 1777, Maximilian Stoll of Vienna described cancer of the gallbladder.
[Edgardo Rivera, MD
]
James L. Abbruzzese, MD; Pancreatic, Hepatic, and Biliary Carcinomas, Medical Oncology: A Comprehensive Review
[1] [DeStoll M: Rationis Mendendi, in Nosocomio Practico vendobonensi.
Part 1 LugduniBatavarum, Haak et Socios et A et J Honkoop 1788, ]
19th century
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In 1805, Philipp Bozzini made the first attempt to observe inside the living human body using a tube he named Lichtleiter (light-guiding instrument) to examine the urinary tract, the rectum, and the human pharynx. This is the earliest description of endoscopy.
[ The Origin of Endoscopes, Olympus history]
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Charles Emile Troisier described enlargement of in abdominal cancer.
[Anton Sebastian, A Dictionary of the History of Medicine, ]
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In 1823, William Prout discovered that stomach juices contain hydrochloric acid.
[ Prout, W. On the nature of the acid and saline matters usually existing in the stomachs of animals. – Philos. Transactions, 1824, 1, 45.]
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In 1833, William Beaumont published Experiments and Observations on the Gastric Juice and the Physiology of Digestion following years of experimenting on test subject Alexis St. Martin.
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In 1868, Adolf Kussmaul, a well-known German physician, developed the gastroscope. He perfected the technique on a Sword swallowing.
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In 1871, at the society of physicians in Vienna, Karl Stoerk demonstrated an esophagoscope made of two telescopic metal tubes, initially devised by Waldenburg in 1870.
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In 1876, Karl Wilhelm von Kupffer described the properties of some liver cells now called .
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In 1883, Hugo Kronecker and Samuel James Meltzer studied oesophageal manometry in humans.
20th century
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In 1915, Jesse McClendon tested Gastric acid of human stomach in situ.
[McClendon J. F. New hydrogen electrodes and rapid methods of determining hydrogen ion concentrations. – Amer. J. Physoil., 1915, 38, 2, 180.]
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In 1921–22, Walter Alvarez did the first electrogastrography research.
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Rudolf Schindler described many important diseases involving the human digestive system during World War I in his illustrated textbook and is portrayed by some as the "father of gastroscopy". He and Georg Wolf developed a semiflexible gastroscope in 1932.
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In 1932, Burrill Bernard Crohn described Crohn's disease.
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In 1957, Basil Hirschowitz introduced the first prototype of a fibreoptic gastroscope.
21st century
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In 2005, Barry Marshall and Robin Warren of Australia were awarded the Nobel Prize in Physiology or Medicine for their discovery of Helicobacter pylori (1982/1983) and its role in peptic ulcer disease. James Leavitt assisted in their research, but the Nobel Prize is not awarded posthumously so he was not included in the award.
Disease classification
1.
International Classification of Disease (ICD 2007)/WHO classification:
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Chapter XI, Diseases of the digestive system,(K00-K93)
2.
MeSH subject Heading:
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Gastroenterology (G02.403.776.409.405)
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Gastroenterological diseases(C06.405)
3.
National Library of Medicine Catalogue (NLM classification 2006):
Procedures
Colonoscopy
A procedure using a
Endoscope that is passed through the
Human anus to visualize the
rectum and the entire length of the colon. The procedure is performed either to look for
Colorectal polyp and/or colon cancer in somebody without symptoms, referred to as screening, or to further evaluate symptoms including
rectal bleeding,
Melena, change in bowel habits or stool consistency (diarrhea, pencil-thin stool), abdominal pain, and unexplained weight loss. Before the procedure, the physician might ask the patient to stop taking certain medications including blood thinners, aspirin, diabetes medications, or nonsteroidal anti-inflammatory drugs. A
Bowel cleansing is usually taken the night before and into the morning of the procedure which consists of an
enema or
, either pills or powder dissolved in liquid, that will cause diarrhea. The procedure might need to be stopped and rescheduled if there is stool remaining in the colon due to an incomplete bowel prep because the physician can not adequately visualize the colon. During the procedure, the patient is
Sedation and the scope is used to examine the entire length of the colon looking for polyps, bleeding, or abnormal tissue. A
biopsy or
Polypectomy can then be performed and the tissue sent to the lab for evaluation. The procedure usually takes thirty minutes to an hour followed by a one to two hour observation period. Complications include bloating, cramping, a reaction to anesthesia, bleeding, and a hole through the wall of the colon that may require repeat colonoscopy or surgery. Signs of a serious complication requiring urgent or emergent medical attention include severe pain in the abdomen, fever, bleeding that does not improve, dizziness, and weakness.
Sigmoidoscopy
A procedure similar to a colonoscopy using a long thin tube with a camera (scope) passed through the
Human anus but only intended to visualize the
rectum and the
Sigmoid colon closest to the rectum. All aspects of the procedure are the same as for a colonoscopy with the exception that this procedure only lasts ten to twenty minutes and is done without sedation. This usually allows for the patient to return to normal activities immediately after the procedure is finished.
Esophagogastroduodenoscopy (EGD)
procedure using a
Endoscope that is passed through the mouth to view the
esophagus ("esophago-"),
stomach ("gastro-"), and the
duodenum ("duodeno-"). It is also referred to as upper endoscopy or just endoscopy. The procedure is performed for further evaluation of symptoms including persistent
heartburn,
indigestion,
Hematemesis,
Melena, persistent nausea and vomiting, pain,
Dysphagia,
Odynophagia, and unexplained weight loss. It is also performed for further testing following a lab test that shows
Anemia without a known cause or an abnormal barium swallow. The procedure can be used to diagnose many disorders through direct visualization or tissue biopsy including esophageal varices, esophageal strictures, gastroesophageal reflux disease, Barrett's esophagus, cancer,
Coeliac disease,
gastritis, peptic ulcer disease, and a H. pylori infection. Intra-operative techniques can then be used for treatment of certain disorders like banding esophageal varices or dilating esophageal strictures. The patient will likely be required to not eat or drink anything starting 4 hours prior to the procedure. Sedation is usually required for patient comfort. This procedure usually lasts around thirty minutes followed by a one to two hour observation period. Side effects include
bloating, nausea, and a sore throat for 1 to 2 days. Complications are rare but include reaction to the anesthesia, bleeding, and a hole through the wall of the esophagus, stomach, or small intestine which could require surgery. Signs of a serious complication requiring urgent or emergent medical attention include chest pain, problems breathing, problems swallowing, throat pain that gets worse, vomiting with blood or the appearance of "coffee-grounds", worsening abdominal pain, bloody or black tarry stool, and fever.
Endoscopic Retrograde Cholangiopancreatography (ERCP)
A procedure using a
Endoscope passed through the mouth into the
Duodenum to locate, diagnose, and treat disorders related to the
Bile duct and
. These ducts carry fluids that help with digesting food from the liver, gallbladder, and pancreas and can become narrowed or blocked as a result of
, infection, inflammation, pancreatic pseudocysts, and tumors of the bile ducts or pancreas. As a result, one may experience back pain,
Jaundice, and an abnormal lab test showing an elevated bilirubin level which could necessitate this procedure. However, the procedure is not recommended if the patient has acute pancreatitis unless the level of bilirubin remains high or is increasing which could suggest the blockage is still present. The patient will likely be required to not eat or drink anything starting 8 hours prior to the procedure. After the patient is sedated, the physician will pass the scope through the mouth, esophagus, stomach, and into the duodenum to locate the opening where the ducts drain into the small intestine. The physician can then inject dye into these ducts and take X-rays which show a real time view, via
fluoroscopy, allowing the physician to locate and relieve the blockage. This is done through multiple techniques including cutting the opening and creating a bigger hole for drainage, removing gallstones and other debris, dilating narrow parts of the ducts, or placing a stent which keeps the ducts open. The physician can also take a
biopsy of the ducts to evaluate for cancer, infection, or inflammation. Side effects include bloating, nausea, or a sore throat for one to two days. Complications include
pancreatitis, infection of the bile ducts or
Cholecystitis, bleeding, reaction to the anesthesia, and perforation of any structures that the scope or its instruments pass but particularly the duodenum, bile duct, and pancreatic duct. Signs of a serious complication requiring urgent or emergent medical attention include bloody or
Melena, chest pain, fever, worsening abdominal pain, worsening throat pain, problems breathing, problems swallowing, vomit that is bloody or looks like coffee-grounds. Most of the time complications from this procedure require hospitalization for treatment.
Ultrasound and Bowel Ultrasound
Ultrasound has become a standard tool in many medical settings. Its widespread availability, affordability, safety, and lack of radiation have established it as a common initial diagnostic method. In gastroenterology, ultrasound is highly accurate in diagnosing various conditions (e.g.,
Appendicitis,
Diverticulitis). Furthermore, bowel ultrasound is crucial for identifying and managing Inflammatory bowel disease and their complications, including the early detection of Crohn's disease recurrence after surgery, as highlighted in the ECCO–ESGAR guidelines.
[Maaser, C.; Sturm, A.; Vavricka, S.R.; Kucharzik, T.; Fiorino, G.; Annese, V.; Calabrese, E.; Baumgart, D.C.; Bettenworth, D.; Borralho Nunes, P.; et al. ECCO-ESGAR Guideline for Diagnostic Assessment in IBD Part 1: Initial diagnosis, monitoring of known IBD, detection of complications. J. Crohn’s Colitis 2019, 13, 144–164.] Modern ultrasound techniques like contrast-enhanced ultrasound offer real-time functional and vascular information, improving diagnostic capabilities. Additionally, operative abdominal ultrasound is increasingly important in minimally invasive interventions, including guided
Biopsy, drainage, and thermal ablation of liver lesions.
Nevertheless, the accuracy of ultrasound is operator-dependent, and inadequate training can lead to diagnostic errors.
[Wüstner, M.; Radzina, M.; Calliada, F.; Cantisani, V.; Havre, R.F.; Jenderka, K.V.; Kabaalioğlu, A.; Kocian, M.; Kollmann, C.; Künzel, J.; et al. Professional Standards in Medical Ultrasound—EFSUMB Position Paper (Short Version)—General Aspects. Ultraschall Med. 2022, 43, 456–463. ] The European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) has established guidelines to define professional standards and the minimum training needed for ultrasound examinations. These guidelines outline three levels of expertise based on anatomical knowledge, the ability to assess diseases using ultrasound, and the volume of exams performed (at least 300 per year for level 1).
[Wüstner, M.; Radzina, M.; Calliada, F.; Cantisani, V.; Havre, R.F.; Jenderka, K.V.; Kabaalioğlu, A.; Kocian, M.; Kollmann, C.; Künzel, J.; et al. Professional Standards in Medical Ultrasound—EFSUMB Position Paper (Short Version)—General Aspects. Ultraschall Med. 2022, 43, 456–463]
/ref>
Disorders
Esophagus
Gastroesophageal reflux disease (GERD)
condition that is a result of stomach contents consistently coming back up into the esophagus causing troublesome symptoms or complications.
Symptoms are considered troublesome based on how disruptive they are to a patient's daily life and well-being. This definition was standardized by the Montreal Consensus in 2006.
Symptoms include a
heartburn in the middle of the chest and feeling stomach contents coming back up into the mouth. Other symptoms include chest pain, nausea,
Dysphagia,
Odynophagia, coughing, and hoarseness.
Risk factors include obesity, pregnancy, smoking,
hiatal hernia, certain medications, and certain foods. Diagnosis is usually based on symptoms and medical history, with further testing only after treatment has been ineffective. Further diagnosis can be achieved by measuring how much acid enters the esophagus or looking into the esophagus with a scope. Treatment and management options
include lifestyle modifications, medications, and surgery if there is no improvement with other interventions. Lifestyle modifications include not lying down for three hours after eating, lying down on the left side, elevating head while laying by elevating head of the bed or using extra pillows, losing weight, stopping smoking, and avoiding coffee, mint, alcohol, chocolate, fatty foods, acidic foods, and spicy foods. Medications include
, proton pump inhibitors, H2 receptor blockers. Surgery is usually a Nissen fundoplication and is performed by a surgeon. Complications of longstanding GERD can include
Esophagitis that may cause bleeding or ulcer formation, narrowing of the esophagus leading to swallowing issues, a change in the lining of the esophagus that can increase the chances of developing cancer (Barrett's esophagus), chronic cough, asthma,
Laryngitis leading to hoarseness, and
Acid erosion of tooth enamel leading to dental issues.
Barrett's esophagus
A condition in which the lining of the esophagus changes to look more like the lining of the intestine and increases the risk of developing esophageal cancer.
There are no specific symptoms although symptoms of GERD may be present for years prior as it is associated with a 10–15% risk of Barrett's esophagus.
Risk factors include chronic GERD for more than 5 years, being age 50 or older, being non-Hispanic white, being male, having a family history of this disorder, belly fat, and a history of smoking.
Diagnosis can be made by looking into the esophagus with a scope and possibly taking a
biopsy of the lining of the esophagus. Treatment includes managing GERD, destroying abnormal parts of the esophagus, removing abnormal tissue in the esophagus, and
Esophagectomy as performed by a general surgeon.
Further management could include periodic surveillance with repeat scopes at certain intervals determined by the physician, likely not more frequently than every three to five years.
Complications from this disorder can result in a type of cancer called esophageal adenocarcinoma.
Education and training
United States
Gastroenterology is a subspecialty of internal medicine and therefore requires three years of internal medicine residency training followed by three additional years in a dedicated gastroenterology fellowship.
This training is certified by the American Board of Internal Medicine (ABIM) and the American Osteopathic Board of Internal Medicine (AOBIM) and must be completed at a program accredited by the Accreditation Council for Graduate Medical Education (ACGME).
Other national societies that oversee training include the American College of Gastroenterology (ACG), the American Gastroenterological Association (AGA), and the American Society for Gastrointestinal Endoscopy (ASGE).
Scope of practice
Gastroenterologists see patients both in the clinic and the hospital setting. They can order diagnostic tests, prescribe medications, and perform a number of diagnostic and
Therapy procedures including
colonoscopy, esophagogastroduodenoscopy (EGD), endoscopic retrograde cholangiopancreatography (ERCP), endoscopic ultrasound (EUS), and
liver biopsy.
In Gastroenterology, as in other specialties, telehealth has led to a reshaping of healthcare systems by introducing new ways of providing care, facilitating access to services throughout the entire Countries.
Subspecialties
Some gastroenterology trainees will complete a "fourth-year" (although this is often their seventh year of graduate medical education) in transplant
hepatology, advanced interventional
endoscopy, inflammatory bowel disease,
motility, or other topics.
Advanced endoscopy, sometimes called interventional or surgical endoscopy, is a sub-specialty of gastroenterology that focuses on advanced endoscopic techniques for the treatment of pancreatic, hepatobiliary, and gastrointestinal disease. Interventional gastroenterologists typically undergo an additional year of rigorous training in advanced endoscopic techniques including endoscopic retrograde cholangiopancreatography, endoscopic ultrasound-guided diagnostic and interventional procedures, and advanced resection techniques including endoscopic mucosal resection and endoscopic submucosal dissection. Additionally, the performance of endoscopic bariatric procedures is also performed by some advanced endoscopists.
Hepatology, or hepatobiliary medicine, encompasses the study of the liver, pancreas, and biliary tree, and is traditionally considered a sub-specialty of gastroenterology, while proctology encompasses disorders of the Human anus, rectum, and Large intestine and is considered a sub-specialty of general surgery.
Professional organizations
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American College of Gastroenterology (ACG)
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American Gastroenterological Association (AGA)
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American Society for Gastrointestinal Endoscopy (ASGE)
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World Gastroenterology Organisation (WGO)
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British Society of Gastroenterology
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United European Gastroenterology The United European Gastroenterology (UEG) was formally established in 1992. Over the years, UEG has grown significantly, establishing itself as a leading and prestigious medical specialty organization worldwide. UEG's mission is to advance the field of digestive diseases through prevention, research, diagnosis, treatment, and increased awareness. It unites over 50,000 professionals, including members from national and specialist societies, individual experts, and scientists in digestive health. UEG organizes the annual UEG Week, a major international gastroenterology congress. It also focuses on education, research support, and advocating for clinical standards and public health policies related to digestive diseases in Europe. UEG publishes the UEG Journal and the UEG White Book, which analyzes the burden and economic impact of digestive diseases in Europe.
Academic journals
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The American Journal of Gastroenterology
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Clinical Gastroenterology and Hepatology
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Endoscopy
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Gastroenterology
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Gastrointestinal Endoscopy
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Gut
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Inflammatory Bowel Diseases
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Journal of Clinical Gastroenterology
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Journal of Crohn's and Colitis
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Neurogastroenterology & Motility
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World Journal of Gastroenterology
