Gastroenterology

Gastroenterology is the branch of medicine focused on the digestive system and its disorders. The digestive system consists of the gastrointestinal tract, sometimes referred to as the GI tract, which includes the esophagus, stomach, small intestine and large intestine as well as the accessory organs of digestion which include the pancreas, gallbladder, and liver.
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. Physicians who specialize in the medical specialty of gastroenterology are called gastroenterologists or sometimes GI doctors.
Some of the most common conditions managed by gastroenterologists include gastroesophageal reflux disease, gastrointestinal bleeding, irritable bowel syndrome, inflammatory bowel disease 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 Egyptian papyri, John F. Nunn identified significant knowledge of gastrointestinal diseases among practicing physicians during the periods of the pharaohs. Irynakhty, of the tenth dynasty, 2125 B.C., was a court physician specializing in gastroenterology, sleeping, and proctology.
Ancient Greeks attributed digestion to 'concoction,' theorizing that it was the result of the heat of the body acting upon food in the stomach, causing it to mature and ripen.
Galen's concept of the stomach having four faculties was widely accepted up to modernity in the seventeenth century.

18th century

Italian Lazzaro Spallanzani was among the early physicians to disregard Galen's theories, and in 1780 he gave experimental proof on the action of gastric juice on foodstuffs.
In 1767, German Johann von Zimmermann wrote an important work on dysentery.
In 1777, Maximilian Stoll of Vienna described cancer of the gallbladder.
19th century
In 1805, Philipp Bozzini made the first attempt to observe inside the living human body using a tube he named Lichtleiter to examine the urinary tract, the rectum, and the pharynx. This is the earliest description of endoscopy.
Charles Emile Troisier described the enlargement of lymph nodes in abdominal cancer.
In 1823, William Prout discovered that stomach juices contain hydrochloric acid.
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.
In 1868, Adolf Kussmaul, a well-known German physician, developed the gastroscope. He perfected the technique on a sword swallower.
In 1871, at the society of physicians in Vienna, Carl Stoerk demonstrated an esophagoscope made of two telescopic metal tubes, initially devised by Waldenburg in 1870.
In 1876, Karl Wilhelm von Kupffer described the properties of some liver cells now called Kupffer cells.
In 1883, Hugo Kronecker and Samuel James Meltzer studied oesophageal manometry in humans.

Image:McClendon pH-probe.png|60px|thumb|McClendon's pH-probe

20th century

In 1915, Jesse McClendon tested the acidity of the human stomach in situ.
In 1921–22, Walter Alvarez did the first electrogastrography research.
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.
In 1932, Burrill Bernard Crohn described Crohn's disease.
In 1957, Basil Hirschowitz introduced the first prototype of a fibreoptic gastroscope.
21st century
In 2005, Barry Marshall and Robin Warren of Australia were awarded the Nobel Prize in Physiology or Medicine for their discovery of Helicobacter pylori 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 Diseases /WHO classification:

Chapter XI, Diseases of the digestive system,

2. MeSH subject Heading:

Gastroenterology
Gastroenterological diseases

3. National Library of Medicine Catalogue :

Digestive system
Procedures

Colonoscopy

A procedure using a long thin tube with a camera passed through the anus to visualize the rectum and the entire length of the colon. It is performed to screen for colon polyps and Colorectal cancer, or to evaluate symptoms such as rectal bleeding, dark stools, changes in bowel habits, abdominal pain, and unexplained weight loss. During the procedure, the patient is usually sedated and the colon is examined for polyps, bleeding, or abnormal tissue; a biopsy or polyp removal may be performed. The procedure typically takes 30–60 minutes, followed by a brief observation period. Complications can include bloating, cramping, reaction to anesthesia, bleeding, and perforation of the colon.

Sigmoidoscopy

A procedure similar to a colonoscopy using a long thin tube with a camera passed through the anus but only intended to visualize the rectum and the last part of the 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)

A flexible endoscope is passed through the mouth to examine the esophagus, stomach, and duodenum. EGD is used to evaluate symptoms such as persistent heartburn, difficulty swallowing, upper-GI bleeding, unexplained anemia or weight loss, and abnormal imaging or lab results. The procedure allows direct visualization, biopsy for histology, and therapies including banding of esophageal varices and dilation of strictures. Most examinations take about 15–30 minutes. Common transient effects are bloating and a sore throat; uncommon risks include reactions to sedation, bleeding, and perforation of the esophagus, stomach, or duodenum.

Endoscopic Retrograde Cholangiopancreatography (ERCP)

A procedure using a long thin tube with a camera passed into the first part of the small intestine to locate, diagnose, and treat disorders of the bile and pancreatic ducts. These ducts can be narrowed or blocked by gallstones, infection, inflammation, pancreatic pseudocysts, or tumors, causing symptoms such as back pain or jaundice and laboratory findings such as elevated bilirubin. Under fluoroscopic guidance, contrast is injected into the ducts to visualize the anatomy; treatments can include sphincterotomy, stone extraction, dilation of strictures, stent placement, and tissue biopsy. Complications may include pancreatitis, infection, bleeding, reaction to anesthesia, and perforation of the duodenum or ducts.

Ultrasound and Bowel 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. 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. 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 biopsies, drainage, and thermal ablation of liver lesions.
Nevertheless, the accuracy of ultrasound is operator-dependent, and inadequate training can lead to diagnostic errors. The European Federation of Societies for Ultrasound in Medicine and Biology 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.
A recent study indicated that the majority of young Italian gastroenterologists acquired their ultrasound skills during their gastroenterology training. Throughout their training, participants performed a median of 320 abdominal ultrasound examinations and 240 bowel ultrasound examinations.

Disorders

Esophagus

Gastroesophageal reflux disease (GERD)

A 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 painful feeling in the middle of the chest and feeling stomach contents coming back up into the mouth. Other symptoms include chest pain, nausea, difficulty swallowing, painful swallowing, 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 antacids, proton pump inhibitors, H2 receptor blockers. Surgery is usually a Nissen fundoplication and is performed by a surgeon. Complications of longstanding GERD can include inflammation of the esophagus 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, chronic cough, asthma, inflammation of the larynx leading to hoarseness, and wearing away of tooth enamel leading to dental issues.