Gastroenterology is the branch of medicine focused on the digestive system and its disorders.Diseases affecting the gastrointestinal tract, which include the organs from mouth into anus, along the alimentary canal, are the focus of this speciality. Physicians practicing in this field are called gastroenterologists.Gastroenterologists perform a number of diagnostic and therapeutic procedures including colonoscopy, esophagogastroduodenoscopy (EGD), endoscopic retrograde cholangiopancreatography (ERCP), endoscopic ultrasound (EUS), and liver biopsy.[2] 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.