AbstractBackgroundWe investigated relationships between the Pediatric Appendicitis Score (PAS) and pathological progression and disease severity in pediatric acute appendicitis.MethodsWe retrospectively evaluated 72 children who underwent surgery for acute appendicitis. We divided them into groups: simple appendicitis (n = 28) or complicated appendicitis (n = 44). We compared the influence of age, body temperature, blood test findings, hospitalization period, number of complications, and PAS between the groups. We calculated the sensitivity, specificity, positive predictive value, and negative predictive value of the PAS for diagnosing complicated appendicitis. A receiver operating characteristic curve was constructed to evaluate the cut‐off value for diagnosing complicated appendicitis. To assess the severity of acute appendicitis, we divided the patients into groups according to that cut‐off value.ResultsThere were statistically significant differences in the PAS between simple appendicitis and complicated appendicitis (5.8 versus 7.9). The receiver operating characteristic curve indicated a PAS cut‐off value of 8. A PAS ≥ 8 had a sensitivity of 73%, a specificity of 89%, a positive predictive value of 91%, and a negative predictive value of 68%. A PAS ≥ 8 was associated with significantly longer hospitalization and more complications than a PAS < 8.ConclusionsThe PAS may be associated with pathological progression and disease severity in appendicitis.