Gastroenterological emergencies in the tropics.

Significant differences exist in the prevalence of most gastroenterological emergencies in tropical compared with temperate countries. Both ethnic and environmental (often clearly defined geographically) factors are relevant. The major oesophageal lesions which can present acutely in tropical countries are varices and carcinoma; bleeding and obstruction are important sequelae. Peptic ulcer disease (and its complications), often associated (not necessarily causally) with Helicobacter pylori infection, has marked geographical variations in incidence. Emergencies involving the small intestine are dominated by severe dehydration, and its sequelae, resulting from secretory diarrhoea, most notably cholera. However, enteritis necroticans ('pig bel' disease), paralytic ileus (sometimes caused by antiperistaltic agents) and obstruction (secondary to luminal helminths, volvulus and intussusception) are other important problems, especially in infants and children. Enteric fever is occasionally complicated by perforation and haemorrhage; the former (which is notoriously difficult to manage) is accompanied by significant mortality. Ileocaecal tuberculosis is a major cause of right iliac fossa pathology--sometimes associated with malabsorption; amoeboma is an important clinical differential diagnosis. The colon can be involved in invasive Entamoeba histolytica infection (which, like complicated enteric fever, is difficult to manage if the fulminant form, with perforation, ensues), shigellosis, volvulus and intussusception. Acute colonic dilatation occasionally follows Salmonella sp., Shigella sp., Campylobacter jejuni, Yersinia enterocolitica and rarely E. histolytica infections. Acute hepatocellular failure is a major cause of morbidity and mortality in the tropics and subtropics. It usually results from viral hepatitis (HBV, sometimes complicated by HDV, and HCV), but there is a long list of differential diagnoses. Hepatotoxicity resulting from herbs, chemotherapeutic agents or alcohol also occurs not infrequently. Chronic liver disease and its sequelae (often long-term results of viral hepatitis) are commonplace. Haematemesis and hepatocellular failure are usually very difficult to manage due to a lack of sophisticated support techniques in developing countries. Invasive hepatic amoebiasis usually responds well to medical management; however, spontaneous perforation can occur and the consequences of this are serious. Pyogenic liver abscess, although far less common than amoebic 'abscess', carries a bad prognosis whatever the method(s) of management. Hydatidosis and schistosomiasis also involve the liver, and helminthiases are important in the context of biliary tract disease. Gall stones are unusual in most tropical settings. Acute pancreatitis is overall unusual, but chronic calcific pancreatitis can present as an acute abdominal emergency.