The character and severity of symptoms of gastroenteritis vary. Generally, onset is sudden, with anorexia, nausea, vomiting, abdominal cramps, and diarrhea (with or without blood and mucus). Malaise and myalgias may occur. The abdomen may be distended and mildly tender; in severe cases, muscle guarding may be present. Gas-distended intestinal loops may be palpable. Hyperactive bowel sounds are present on auscultation even without diarrhea (an important differential feature from paralytic ileus, in which bowel sounds are absent or decreased). Persistent vomiting and diarrhea can result in intravascular fluid depletion with hypotension and tachycardia. Hypovolemic shock Hypovolemic shock Shock is a state of organ hypoperfusion with resultant cellular dysfunction and death. Mechanisms may involve decreased circulating volume, decreased cardiac output, and vasodilation, sometimes... read more with vascular collapse and oliguric renal failure may occur in severe cases.