The use of a clinical score, based on patient history and examination, is one way to possibly improve the diagnostic procedure. There are several available scores. In this systematic review, Pediatric Appendicitis Score (PAS) were considered the most reliable. Pediatric Appendicitis Score is the only score specifically developed for children, composed by Samuel in 2002 when analyzing children between 4 and 15 years of age. Pediatric Appendicitis Score has been validated and recommended by some authors, but only one of these studies has included children less than 4 years of age.