Diagnostic validity of signs and symptoms defining the diagnosis of acute appendicitis

: A prospective study of 810 consecutive cases submitted to emergency appendicectomy was performed to determine the predictive value of abdominal pain, nausea, vomiting, fever, abdominal tenderness and total and differential leucocyte count in the diagnosis of appendicitis. Age, sex, time of evolution and degree of inflammation were considered as conditioning factors. Most of the cases were diagnosed within the first 12 h. Pain demonstrated acceptable sensitivity (85.2%) and a high positive predictive value (95.7%) but with an important proportion of false negatives (14.8%). The predictive value of abdominal exploration was 97.6% with a sensitivity of 96.1%. Leucocytosis increased with the degree of inflammation and values above the cut off point established (12,500 leucocytes/dl and 85% segmented) significantly increased the strength of the association. Pain on palpation and leucocytosis with shift to the left increased the sensitivity to 98.1% with false positives of 1.3%. The percentage of acute perforated appendicitis increased from 5 to 15.3% when diagnosis was delayed more than 12 h. Once the clinical manifestations and analytical alterations were established (6 h after initiation of the clinical picture) these did not modify with the time of evolution. The greater the involvement of the appendix the earlier the presentation although, logically, the later the diagnosis the greater the percentage of perforated appendix. The classical criteria of pain, tenderness and leucocytosis with left deviation does not allow the diagnosis of 1.9% of the cases of appendicitis with 1.3% of false positives. Once the clinical manifestations are established, these do not modify with the time of evolution, but the percentage of perforations does increase with time. To reduce this percentage, diagnosis must be made within the first 24 h.