Gastroenterology is a branch of medicine focused on the digestive system and its disorders. Diseases affecting the gastrointestinal tract, which include the organs from mouth to anus, along the alimentary canal, are the focus of this specialty. Physicians practicing in this field are called Gastroenterologists. Gastroenterologists perform a number of diagnostic and therapeutic procedures including colonoscopy, endoscopy, endoscopic retrograde cholangiancreatography (ERCP), endoscopic ultrasound and liver biopsy.