Inclusion Criteria:  Age of at least 15 years old. Clinical diagnosis of acute appendicitis. Treated by: Open appendectomy + double-ring wound-edge protector or Laparoscopic appendectomy. Note: with the aim of avoiding selection bias, all patients presenting risk factors for surgical site infections (eg obesity, diabetes, malnourishment, immunosupression, etc.) will be included in the present study.  Exclusion Criteria:  Patients who did not receive prophylactic antibiotic. Source of abdominal pathology other than the caecal appendix. Follow-up period less than 30 days.