Appendicitis in Children. Clinical, diagnostic and pathogenic factors

Background: Appendicitis is the most common disease requiring abdominal surgery in children. However, the diagnosis of pediatric appendicitis is still a challenge, resulting in perforation and negative appendectomies, especially in girls and young children. Further, the pathogenesis of acute appendicitis is not known. Aim: To examine acute appendicitis in children in the aspects of evaluation of the utility of the pediatric appendicitis score (PAS) in young children and evaluate factors responsible for the late diagnosis in this age group, gender differences, surgical techniques, urinary biomarkers, and the microbiome’s role in the pathogenesis. Results: Young children had lower PAS despite more severe appendicitis. Parent’s and doctor’s delay, and diffuseness in patient history, symptoms, and abdominal examination, contributed to the late diagnosis in this age group. Gender differences were found, especially that preoperative imaging, negative appendectomies and operative complications were more common in girls. Two-trocar laparoscopic appendectomy (LA) resulted in shorter surgery time and fewer scars compared to conventional LA, and the rate of wound infection was low. Leucine-rich -2-glycoprotein (LRG) was elevated in children with appendicitis compared to children without, higher in complicated appendicitis compared to phlegmonous appendicitis, had a ROC AUC 0.86, and an OR for appendicitis of 8.4. LRG in conjunction with PAS showed 95% sensitivity, 90% specificity, 91% PPV, and 95% NPV. Fusobacterium increased and Bacteroides decreased in phlegmonous- and perforated appendicitis but not significantly, and this pattern was not seen in gangrenous appendicitis. No relation could be seen between different bacteria and the degree of inflammation, and there was a wide variation of abundances at phylum, genus and species level within each specific group of patients. Conclusion: PAS should be used with caution in children < 4 years. Diffuse symptoms in younger children lead to delay and to later diagnosis and more complicated appendicitis. There are gender differences in pediatric appendicitis regarding misdiagnosis, severity of appendicitis, and surgical complications. Two-trocar LA is a safe and quick technique with a low rate of postoperative wound infections. LRG is a promising novel urinary biomarker for appendicitis in children. In most cases of appendicitis, a specific bacteria does not seem to be the primary event.