Efficacy of Metronidazole in the Conservative Treatment for Appendiceal Mass

Background In patients with complicated appendicitis, interval appendectomy (IA) with a single broad-spectrum antibiotic sometimes fails. We reviewed our experience of adding metronidazole (MNZ) in such situations. Methods Medical records of children with an appendiceal mass treated with broad-spectrum antibiotics followed by IA from March 2009 to May 2019 were reviewed. In the latter period (after April 2015, Group L, n = 14), MNZ was added if symptoms were not improved by a 3- to 4-day course of antibiotics. The body temperature, white blood cell count (WBC), serum C-reactive protein (CRP), treatment failure, and hospital stay for the initial treatment were collected in the earlier period (Group E, n = 14) and Group L. Results There was no treatment failure. Group E tended to require a longer hospital stay (14.0 vs. 11.1 days, p = 0.099); however, the temperature, WBC, and CRP on admission were not significantly different. In the MNZ-added group (n = 8), the mean rate of change (per day) in WBC before and after the addition of MNZ were −288 ± 1,155 and −3,870 ± 1,634, respectively (p = 0.001). All patients underwent IA in about 3 months. Conclusions This preliminary study may indicate the efficacy of MNZ combined with a broad-spectrum antibiotic followed by IA for intractable appendiceal masses.