Enterobius vermicularis: A Cause of Abdominal Pain Mimicking Acute Appendicitis in Children. A Retrospective Cohort Study

Abstract

Background: Enterobius vermicularis (EV) is the most common helminthic infection in the world. This small parasite is predominant in the pediatric population. The presence of EV in the appendix can cause or mimick appendicitis. The aim of our study was to compare patients with EV infection and those without EV infection, and to identify predictive factors that may help the diagnosis of EV infection in patients presenting with right iliac fossa pain and avoid negative appendectomy.

Methods: A retrospective analysis of all the appendices removed between January 2012 and December 2016 was conducted at the department of pediatric surgery, Hedi Chaker Hospital, Sfax, Tunisia. According to the final histopathological diagnosis, patients with EV infection were compared to those without EV infection. Data including age, sex, white blood cell (WBC) count, neutrophil count, eosinophil count, C-reactive protein, and ultrasound results for both groups were analyzed and compared. The study protocol was approved by the local hospital ethics committee. Statistical analysis was performed using IBM SPSS, version 20. Descriptive analysis in the form of mean and standard deviation was performed on demographic information. Differences between groups were assessed using the student t-test for continuous variables and the χ2 test and Fisher exact test where appropriate for categorical variables.

Results: In total, 540 pediatric appendectomies were performed. Overall, 63.5% of patients were male and 36.5% were female. Mean age was 9.28 ± 2.77 years. 22.2% of procedures were completed laparoscopically, 76.5% were open and 1.3% were converted. The negative appendectomy rate was 11.1%. EV was present in 9.8% of cases. Comparison of clinical, biological, and ultrasound findings between two groups of patients with EV (EV+) and those without EV (EV-) shows a statistical significance for pruritus ani (P < 0.001), WBC count (P < 0.001), neutrophil count (P < 0.001), C-reactive protein (CRP) (P = 0.001), positive ultrasound (P < 0.001), perforation rate (P = 0.009), and negative appendectomy rate (P < 0.001). No significant difference between the two groups was seen when comparing gender (P = 0.271), vomiting (P = 0.130), eosinophil count (P = 0.915), and procedure (P = 0.536).

Conclusion: EV was seen in 9.8% of pediatric appendectomies in our study. Pruritus ani, normal WBC count, normal neutrophil count, and normal CRP level at presentation could predict EV infection in children who present with right iliac fossa pain.

Keywords: Abdominal pain; Acute appendicitis; Appendicectomy; Children; Enterobius vermicularis.