Laboratory tests in patients with suspected acute appendicitis.

The clinical usefulness of preoperative determination of total and differential white blood cell count and C-reactive protein was studied in 113 patients undergoing emergency appendectomy for suspected acute appendicitis. The diagnosis was confirmed in 86 (76%) of the patients. In all 86 cases at least one of the three laboratory tests gave an abnormal result. The highest incidence of abnormal results was found in the most advanced stages of inflammatory reaction in the appendix. In nine of the 27 patients with histologically normal appendix all three laboratory parameters were normal. The "negative appendectomy rate" would have fallen from 24% to 16% in this study if the patients with negative results in all three tests had not been operated on.