The oral cavity is part of the gastrointestinal system and as such the presence of alterations in this district can be the first sign of both systemic and gastrointestinal diseases.[1] By far the most common oral conditions are plaque-induced diseases (e.g., gingivitis, periodontitis, dental caries). Oral symptoms can be similar to lesions occurring elsewhere in the digestive tract, with a pattern of swelling, inflammation, ulcers, and fissures. If these signs are present, then patients are more likely to also have anal and esophageal lesions and experience other extra-intestinal disease manifestations.[2] Some diseases which involve other parts of the GI tract can manifest in the mouth, alone or in combination, including:
Oesophageal diseases include a spectrum of disorders affecting the oesophagus. The most common condition of the oesophagus in Western countries is gastroesophageal reflux disease,[4] which in chronic forms is thought to result in changes to the epithelium of the oesophagus, known as Barrett's oesophagus.[5]: 863–865
Diseases of the intestine may cause vomiting, diarrhoea or constipation, and altered stool, such as with blood in stool. Colonoscopy may be used to examine the large intestine, and a person's stool may be sent for culture and microscopy. Infectious disease may be treated with targeted antibiotics, and inflammatory bowel disease with immunosuppression. Surgery may also be used to treat some causes of bowel obstruction.[5]: 850–862
The normal thickness of the small intestinal wall is 3–5 mm,[8] and 1–5 mm in the large intestine.[9] Focal, irregular and asymmetrical gastrointestinal wall thickening on CT scan suggests a malignancy.[9] Segmental or diffuse gastrointestinal wall thickening is most often due to ischemic, inflammatory or infectious disease.[9] Though less common, medications such as ACE inhibitors can cause angioedema and small bowel thickening.[10]
Diseases affecting the large intestine may cause blood to be passed with stool, may cause constipation, or may result in abdominal pain or a fever. Tests that specifically examine the function of the large intestine include barium swallows, abdominal x-rays, and colonoscopy.[5]: 913–915
Hepatic diseases refers to those affecting the liver. Hepatitis refers to inflammation of liver tissue, and may be acute or chronic. Infectious viral hepatitis, such as hepatitis A, B and C, affect in excess of (X) million people worldwide. Liver disease may also be a result of lifestyle factors, such as fatty liver and NASH. Alcoholic liver disease may also develop as a result of chronic alcohol use, which may also cause alcoholic hepatitis. Cirrhosis may develop as a result of chronic hepatic fibrosis in a chronically inflamed liver, such as one affected by alcohol or viral hepatitis.[5]: 947–958
In order to investigate liver disease, a medical history, including regarding a person's family history, travel to risk-prone areas, alcohol use and food consumption, may be taken. A medical examination may be conducted to investigate for symptoms of liver disease. Blood tests may be used, particularly liver function tests, and other blood tests may be used to investigate the presence of the Hepatitis viruses in the blood, and ultrasound used. If ascites is present, abdominal fluid may be tested for protein levels.[5]: 921, 926–927
Pancreatic diseases that affect digestion refers to disorders affecting the exocrine pancreas, which is a part of the pancreas involved in digestion.[citation needed]
Pancreatic disease may present with or without symptoms. When symptoms occur, such as in acute pancreatitis, a person may experience acute-onset, severe mid-abdominal pain, nausea and vomiting. In severe cases, pancreatitis may lead to rapid blood loss and systemic inflammatory response syndrome. When the pancreas is unable to secrete digestive enzymes, such as with a pancreatic cancer occluding the pancreatic duct, result in jaundice. Pancreatic disease might be investigated using abdominal x-rays, MRCP or ERCP, CT scans, and through blood tests such as measurement of the amylase and lipase enzymes.[5]: 888–894
The Wikipedia article "Gastrointestinal cancer" describes the specific malignant conditions of the gastrointestinal tract. In general, a significant factor in the etiology of gastrointestinal cancers appears to be excessive exposure of the digestive organs to bile acids.[12][13]
^Yamada T; Alpers DH; et al. (2009). Textbook of gastroenterology (5th ed.). Chichester, West Sussex: Blackwell Pub. pp. 2774–2784. ISBN978-1-4051-6911-0.
^"Esophagus Disorders". Medline Plus. U.S. National Library of Medicine. Retrieved 23 December 2013.
^ abcdefghijklmnopqrstuvwNicki R. Colledge; Brian R. Walker; Stuart H. Ralston, eds. (2010). Davidson's principles and practice of medicine. Illustrated by Robert Britton. (21st ed.). Edinburgh: Churchill Livingstone/Elsevier. ISBN978-0-7020-3085-7.