Constant mid-abdominal pain that later shifts to right lower quadrant. Usually worse on movement.
An important symptom almost always associated with acute appendicitis.  Without anorexia the diagnosis of acute appendicitis is in question.
A classic sign is right lower quadrant abdominal tenderness (McBurney's sign). There may be localized rebound tenderness, especially if the appendix is anterior. Compressing the left lower quadrant may also elicit pain in the right lower quadrant (Rovsing's sign). Pain may also be elicited with the patient lying on their left side and slowly extending the right thigh to cause a stretch in the iliopsoas muscle (psoas sign) or by internal rotation of the flexed right thigh (obturator sign).
May occur at any age but is most commonly seen in early teens to late 40s.
Nausea and vomiting are also present in 75% of patients. 
Low-grade, usually a 1°C (1.8°F) increase in body temperature.
Bowel sounds may be reduced, particularly on the right side compared with on the left.
Tachycardia may be present, particularly in patients with perforation. 
Fetor may be present. 
Nausea and vomiting are also present in 75% of patients.  Vomiting usually occurs only once or twice.
Pressing the left side of the abdominal cavity and eliciting pain in right lower quadrant.
Extending the right thigh on left lateral position elicits pain in right lower quadrant.
Pain is elicited at right lower quadrant of abdomen by internal rotation of the flexed right thigh.
A higher incidence of acute appendicitis in Western society may be related to the living conditions and improved personal hygiene. 
A balance of gastrointestinal microbial flora is important for prevention of infection, for digestion, and for providing important nutrients.  Frequent use of antibiotics and improved hygienic conditions lead to decreased exposure and/or imbalance of gastrointestinal microbial flora that may eventually lead to a modified response to viral infection and thereby trigger appendicitis. 
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