The value of the leucocyte count in the diagnosis of acute appendicitis.

Total and differential leucocyte counts were performed on 175 patients with a provisional diagnosis of acute appendicitis. Ninety-six per cent of patients with acute appendicitis had either an abnormal total or differential leucocyte count. Four of 24 patients operated on with a normal leucocyte count had acute appendicitis. It is concluded that leucocytosis of above 10 000/mm3 or a differential in excess of 75% neutrophils supports the clinical diagnosis of acute appendicitis and that routine estimation of the leucocyte count is a useful investigation. While a normal leucocyte count does not exclude even a perforated appendicitis, such a count should prompt further review of the diagnosis, especially in the presence of an atypical history or minimal physical signs.