Diagnostic Criteria for Appendicitis

Laboratory Markers

The white blood cell differential, specifically the absolute neutrophil count (ANC), demonstrates superior sensitivity compared to other laboratory markers in identifying appendicitis, with the American College of Surgeons recommending its use 1, 2
The ANC > 7500/mL was identified as a significant independent risk factor for appendicitis, with a sensitivity of 97.8% in the APPY1 test panel 2
The sedimentation rate has lower diagnostic accuracy than WBC differential, according to the World Journal of Emergency Surgery guidelines 1, 4
The eosinophil count has not been identified as a significant marker for appendicitis in current guidelines from the American College of Surgeons 1, 4

In children, routine laboratory tests including WBC differential with calculation of the absolute neutrophil count are recommended as a strong recommendation by the World Journal of Emergency Surgery guidelines 1, 5
For adults, the white blood cell differential remains valuable when used in combination with clinical scoring systems like AIR or AAS, as suggested by the American College of Emergency Physicians 6
The differential is particularly useful in distinguishing complicated from uncomplicated appendicitis, with neutrophilia being one of the three most sensitive markers (79.7%) for predicting complicated appendicitis 3

No single laboratory test should be used in isolation to diagnose appendicitis, according to the American College of Surgeons guidelines 1, 4
While the WBC differential is the most sensitive laboratory test, imaging studies (particularly ultrasound and CT) have higher overall diagnostic accuracy, as stated by the American College of Radiology 7
The combination of clinical assessment tools with laboratory markers provides the highest diagnostic accuracy, as recommended by the American College of Emergency Physicians 6, 3