The Use of White Blood Cell Count and Left Shift in the Diagnosis of Appendicitis in Children

BACKGROUND:The use of white blood cell (WBC) count and left shift in the diagnosis of appendicitis in pediatric patients is unproven. It is commonly thought that children with appendicitis have an elevated WBC count with a left shift; however, most data supporting this belief stem from studies conducted on appendicitis in adults, not children. The purpose of this investigation was to determine the value of WBC count and differential in the diagnosis of appendicitis in children presenting to the emergency department (ED) with acute abdominal pain. METHODS:Seven hundred twenty-two pediatric ED patients with a primary complaint of nontraumatic abdominal pain were identified by prospective and retrospective methods. White blood cell count with differential was performed on patients with history and physical examination findings that were felt to warrant laboratory investigation. Results of WBC counts were determined as low, normal, or high, with or without a left shift, based on normal age-related values per laboratory protocol for pediatric patients. RESULTS:The diagnosis of appendicitis was made in 10.2% of all patients presenting to the ED with acute abdominal pain. Thirty percent of toddlers (1-3.9 years) with high WBC counts had appendicitis, whereas 0% of toddlers with low WBC counts and 4.8% of toddlers with normal WBC counts had appendicitis (χ = 6.5, P = 0.04). A normal WBC count did not rule out appendicitis in toddlers; however, the negative predictive value (NPV) for normal or low WBC count was high (NPV = 95.6%). In the child age group (4-11.9 years), high WBC count was both sensitive and specific for the diagnosis of appendicitis in children (sensitivity = 71%, specificity = 72%), and the NPV for normal or low WBC count was high (NPV = 89.5%). Lastly, 43.9% of adolescents (12-19 years) with high WBC counts had appendicitis, whereas 0% of adolescents with low WBC counts and 8.3% of adolescents with normal WBC counts had appendicitis (χ = 37.3, P < 0.001). The NPV for a low or normal WBC count was also high in the adolescent group (NPV = 91.9%).Left shift was also strongly associated with appendicitis. Among toddlers, 40% of patients with a left shift had appendicitis, whereas 1.8% of toddlers without a left shift had appendicitis (χ = 25.7, P < 0.001, NPV = 98.2%). Similarly, left shift was strongly associated with appendicitis in children and adolescents. Among children, 54.3% of patients with a left shift had appendicitis, whereas 5.4% of childr