Gastroenterology

• 1. Introduction

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  Gastroenterology takes its name from three Greek roots: gastḗr for belly, énteron for intestine, and logía for the study of something. The word describes the branch of medicine devoted to the digestive system and its disorders. The doctors who practice it are called gastroenterologists, or sometimes simply GI doctors. Their territory is the gastrointestinal tract, often shortened to the GI tract, a continuous passage that runs from the esophagus to the stomach to the small intestine and the large intestine. They also tend to the accessory organs of digestion: the pancreas, the gallbladder, and the liver. This system has a job to perform. It moves material along through a muscular action called peristalsis. It breaks that material down through digestion. It absorbs nutrients the body needs and removes what the body cannot use through defecation. How did physicians learn to look inside this hidden machinery? Who first proved what gastric juice actually does? And how did one bacterium overturn the understanding of a common ulcer? The answers reach back to the age of the pharaohs.

• 2. From Concoction To Chemistry

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  Citing Egyptian papyri, John F. Nunn identified detailed knowledge of gastrointestinal diseases among physicians who practiced during the periods of the pharaohs. One of them has a name. Irynakhty, of the tenth dynasty around 2125 B.C., served as a court physician specializing in gastroenterology, sleeping, and proctology. Ancient Greeks explained digestion through an idea they called concoction. They theorized that the heat of the body acted upon food in the stomach, causing it to mature and ripen like fruit. Galen built on this thinking with a concept of the stomach possessing four faculties. That model held its authority well into modern times, surviving until the seventeenth century. The first serious break with Galen came from Italy. Lazzaro Spallanzani, who lived from 1729 to 1799, was among the early physicians to disregard Galen's theories. In 1780 he supplied experimental proof of how gastric juice acts on foodstuffs. Other eighteenth-century work mapped the diseases themselves. In 1767 the German physician Johann von Zimmermann wrote an important study of dysentery. A decade later, in 1777, Maximilian Stoll of Vienna described cancer of the gallbladder. The next century would put a chemical name to the fluid Spallanzani had studied.

• 3. Learning To Look Inside

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  In 1805, Philipp Bozzini built a tube he named the Lichtleiter, meaning light-guiding instrument, and used it to examine the urinary tract, the rectum, and the pharynx of a living human being. That attempt stands as the earliest description of endoscopy. The instruments grew more capable across the nineteenth century. In 1868 Adolf Kussmaul, a well-known German physician, developed the gastroscope and refined his technique on a sword swallower. Three years later, in 1871, Carl Stoerk demonstrated an esophagoscope to the society of physicians in Vienna, built from two telescopic metal tubes that Waldenburg had first devised in 1870. The push toward flexibility continued into the twentieth century. Rudolf Schindler, sometimes portrayed as the father of gastroscopy, documented many digestive diseases during World War I in an illustrated textbook. Working with Georg Wolf, he developed a semiflexible gastroscope in 1932. The decisive leap came in 1957, when Basil Hirschowitz introduced the first prototype of a fibreoptic gastroscope. Other observers studied the body's structures rather than its passages. Charles Emile Troisier described the enlargement of lymph nodes in abdominal cancer. In 1876 Karl Wilhelm von Kupffer described the properties of certain liver cells, now known as Kupffer cells in his honor.

• 4. The Acid And The Bacterium

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  In 1823, William Prout discovered that stomach juices contain hydrochloric acid, naming the chemistry behind digestion at last. The study of the stomach soon turned to direct experiment on a living person. In 1833, William Beaumont published Experiments and Observations on the Gastric Juice and the Physiology of Digestion, the result of years of work on his test subject, Alexis St. Martin. Measurement grew steadily more precise. In 1883, Hugo Kronecker and Samuel James Meltzer studied oesophageal manometry in humans. In 1915, Jesse McClendon tested the acidity of the human stomach in situ. Walter Alvarez carried out the first electrogastrography research in 1921 and 1922. One discovery reshaped how doctors understood ulcers. In 2005, Barry Marshall and Robin Warren of Australia were awarded the Nobel Prize in Physiology or Medicine. The prize recognized their discovery of Helicobacter pylori, made in 1982 and 1983, and its role in peptic ulcer disease. James Leavitt assisted in the research. Because the Nobel Prize is not awarded posthumously, he was not included in the award.

• 5. Scopes And Sound Waves

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  Colonoscopy sends a long thin tube fitted with a camera through the anus to view the rectum and the entire length of the colon. It screens for colon polyps and colorectal cancer, and it evaluates symptoms such as rectal bleeding, dark stools, changes in bowel habits, abdominal pain, and unexplained weight loss. The patient is usually sedated, and a biopsy or polyp removal may happen during the exam. The procedure typically takes 30 to 60 minutes, followed by a brief observation period, with possible complications including bloating, cramping, reaction to anesthesia, bleeding, and perforation of the colon. Sigmoidoscopy works much the same way but reaches only the rectum and the last part of the colon nearest to it. That shorter scope lasts ten to twenty minutes and is done without sedation, letting the patient return to normal activities right away. Esophagogastroduodenoscopy, abbreviated EGD, passes a flexible endoscope through the mouth to examine the esophagus, stomach, and duodenum. It can treat as well as look, offering banding of esophageal varices and dilation of strictures, with most examinations taking about 15 to 30 minutes. Endoscopic Retrograde Cholangiopancreatography, or ERCP, reaches into the first part of the small intestine to diagnose and treat disorders of the bile and pancreatic ducts. Under fluoroscopic guidance, contrast is injected to reveal the anatomy, and treatments can include sphincterotomy, stone extraction, dilation of strictures, stent placement, and tissue biopsy. Ultrasound offers a gentler first look. Its availability, affordability, safety, and lack of radiation have made it a common initial diagnostic method, highly accurate in conditions such as appendicitis and diverticulitis. Bowel ultrasound is crucial for inflammatory bowel disease, including the early detection of Crohn's disease recurrence after surgery, as highlighted in the ECCO-ESGAR guidelines. Accuracy, though, depends on the operator. The European Federation of Societies for Ultrasound in Medicine and Biology has set guidelines defining three levels of expertise, with level 1 requiring at least 300 exams per year.

• 6. When The Esophagus Falters

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  Gastroesophageal reflux disease, known as GERD, occurs when stomach contents consistently come back up into the esophagus and cause troublesome symptoms or complications. The Montreal Consensus standardized that definition in 2006, judging symptoms troublesome by how much they disrupt a patient's daily life and well-being. Sufferers feel a painful sensation in the middle of the chest and sense stomach contents rising into the mouth, alongside nausea, difficulty swallowing, coughing, and hoarseness. Risk factors run from obesity and pregnancy to smoking, hiatal hernia, and certain medications and foods. Lifestyle changes form the first line of management. Patients are advised not to lie down for three hours after eating, to lie on the left side, to elevate the head while lying down, to lose weight, to stop smoking, and to avoid coffee, mint, alcohol, chocolate, and fatty, acidic, or spicy foods. Medications include antacids, proton pump inhibitors, and H2 receptor blockers, while surgery, usually a Nissen fundoplication, is reserved for cases that do not improve. Left unchecked over years, GERD can lead to a quieter and more dangerous change. The lining of the esophagus can begin to resemble the lining of the intestine, a condition called Barrett's esophagus. Chronic GERD carries a 10 to 15 percent risk of it. Other risk factors include GERD for more than 5 years, being age 50 or older, being non-Hispanic white, being male, having a family history, carrying belly fat, and a history of smoking. Diagnosis comes from looking into the esophagus with a scope and possibly taking a biopsy, with surveillance scopes repeated likely no more often than every three to five years. The most serious outcome is a cancer called esophageal adenocarcinoma.

• 7. Becoming A Gastroenterologist

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  In the United States, gastroenterology is a subspecialty of internal medicine, which means a long road of training. A doctor completes three years of internal medicine residency, then three additional years in a dedicated gastroenterology fellowship. Certification runs through the American Board of Internal Medicine and the American Osteopathic Board of Internal Medicine, at programs accredited by the Accreditation Council for Graduate Medical Education. Once trained, gastroenterologists see patients in both the clinic and the hospital. They order diagnostic tests, prescribe medications, and perform procedures including colonoscopy, EGD, ERCP, endoscopic ultrasound, and liver biopsy. Telehealth has begun to reshape how that care reaches patients across entire countries. Some trainees press further into a so-called fourth year, often their seventh year of graduate medical education overall. They specialize in transplant hepatology, advanced interventional endoscopy, inflammatory bowel disease, motility, or other topics. Advanced endoscopy, also called interventional or surgical endoscopy, devotes an additional year to techniques such as endoscopic ultrasound-guided procedures, endoscopic mucosal resection, and endoscopic submucosal dissection. Hepatology covers the liver, pancreas, and biliary tree as a subspecialty of gastroenterology. Proctology, dealing with the anus, rectum, and colon, sits instead within general surgery.

• 8. The Global Profession

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  The American College of Gastroenterology began in 1932 when a group of 10 gastroenterologists came together in New York City. It now counts more than 16,000 members from 86 countries, publishes journals including The American Journal of Gastroenterology, and provides $27 million in research grants and career awards, with $2.2 million distributed in 2022. The American Gastroenterological Association is older still, founded in 1897, and now includes over 16,000 members worldwide under the mission to empower clinicians and researchers to improve digestive health. It runs an annual meeting called Digestive Disease Week and gave $2.56 million to 61 investigators in 2022. The American Society for Gastrointestinal Endoscopy, founded in 1941, gathers around 15,000 members and publishes the monthly journal Gastrointestinal Endoscopy. The reach extends well beyond the United States. The World Gastroenterology Organisation, founded in 1958, brings together 119 Member Societies and 4 regional affiliated associations representing some 60,000 individuals. It runs 23 training centers around the world and marks World Digestive Health Day each year on the 29th of May. The United European Gastroenterology was formally established in 1992, unites over 50,000 professionals, and organizes the annual UEG Week. Among its publications is the UEG White Book, which analyzes the burden and economic impact of digestive diseases in Europe.