In a persistently befuddling contradiction, the same specialty that sometimes needs to be physically restrained from pan-CT-ing every trauma patient is simultaneously concerned about the negative appendectomy rate. Maximum sensitivity in one instance, maximum specificity in the other.
An avenue that has been bludgeoned to death many a time is the utility of the WBC for diagnosis of appendicitis. This study in Pediatrics out of U.C. Davis, again, attempts to establish test-thresholds for WBC to with the ultimate goal of reducing the negative appendectomy rate. At U.C. Davis, similar to national rates, 2.6% of children taken for appendectomy were demonstrated to have a normal appendix. They observe that neutrophil counts and overall WBC counts were within the normal range in over 80% of these patients, and describe a potential management strategy to improve their negative appendectomy rate. For WBC <9,000 or <8,000, the negative appendectomy rate could be improved to 0.6% or 1.2% – as long as the surgeons were content with a sensitivity of 92% to 95%.
Thus the conundrum. How many cases of appendicitis are you willing to allow to progress to perforation – associated with not-insignificant morbidity – in order to minimize the negative appendectomy rate? Considering up to 20% of appendicitis will have a normal WBC count – despite addressing an important problem – the solution presented by these leukocytosis cut-offs does not appear to provide the ultimate answer.
“Use of White Blood Cell Count and Negative Appendectomy Rate”
http://pediatrics.aappublications.org/content/133/1/e39.abstract