The value of laboratory tests in patients suspected of acute appendicitis.

The clinical usefulness of laboratory tests was examined in 258 patients admitted to the emergency room with the general practitioner's tentative diagnosis, acute appendicitis. Acute appendectomy was performed on 91 patients. Histological examination of the appendix confirmed the diagnosis in 69 cases (acute appendicitis 20, phlegmonous appendicitis 36, perforation 13). Seven patients with appendicular infiltrate were not subjected to operation but the diagnosis was clear from clinical examination. On close examination/operation by the surgical team, 96 admitted patients were excluded from the primary diagnosis, acute appendicitis, and served as a control group. Receiver Operation Characteristic curves (ROC-curves) showed that the sensitivity and specificity and hence diagnostic efficiency for total white blood cell count, number of segmented leukocytes and C-reactive protein concentration for the detection of acute appendicitis were higher than for erythrocyte sedimentation rate, alpha 1-antiproteinase concentration and body temperature. We observed that when all three parameters, C-reactive protein, white blood cell count and segmented leukocytes, are within the normal range the diagnosis, acute appendicitis is highly unlikely. The diagnostic value of the different laboratory parameters appears, moreover, to be highly dependent on the degree of inflammation/perforation and the development of appendicular infiltration. However, diagnostic efficiency can be improved, and unnecessary surgery prevented, by performance of an appropriately selected combination of laboratory tests combined with evaluation of clinical symptoms.