Does prolonged postoperative intravenous antibiotic therapy prevent intra-abdominal abscess after pediatric perforated appendicitis?—a retrospective comparative study

Introduction

Background

Perforated appendicitis is a common cause of acute abdomen in children that often necessitates emergency surgery. One of the most concerning postoperative complications is the development of intra-abdominal abscesses.

Rationale and knowledge gap

Despite advancements in surgical techniques and perioperative management, the ideal duration of postoperative antibiotic therapy to prevent these abscesses remains controversial (1,2). Traditionally, extended antibiotic courses of 7 days or more have been standard, especially in cases of perforated appendicitis where the risk of infection is elevated (3). However, several recent studies suggest that shorter durations of antibiotic therapy may be just as effective and could reduce complications related to antibiotic overuse, such as antimicrobial resistance and delayed recovery (3).

Objective

The purpose of this study is to determine whether prolonged postoperative intravenous antibiotic therapy decreases the incidence of intra-abdominal abscesses in pediatric patients with perforated appendicitis. By comparing outcomes between patients receiving extended antibiotic treatment and those receiving shorter courses, we sought to establish if a longer duration of therapy offers any additional benefit. We present this article in accordance with the STROBE reporting checklist (available at https://asj.amegroups.com/article/view/10.21037/asj-2025-1-87/rc).

Methods

A retrospective review was conducted on pediatric patients who underwent appendectomy for perforated appendicitis from January 2013 to December 2022 at St. Marianna University School of Medicine. Perforated appendicitis was defined by the presence of a visible perforation in the appendix. Patients with insufficient data were excluded from the analysis.

Patients were classified into two groups according to the median duration of postoperative antibiotic administration. Group A consisted of patients who received antibiotics for 7 days or more, and Group B consisted of those treated for less than 7 days. The variables analyzed included patient age, sex, preoperative white blood cell (WBC) count, and preoperative C-reactive protein (CRP) level. The primary outcome was the incidence of postoperative intra-abdominal abscess formation. For patients who developed an abscess, the number of days until diagnosis and the duration of antibiotic therapy prior to diagnosis were recorded.

Postoperative antibiotic regimens were selected according to institutional practice for pediatric perforated appendicitis. In principle, cefmetazole (CMZ) or flomoxef (FMOX) was used as backbone therapy, with amikacin sulfate (AMK) added for coverage against gram-negative organisms and clindamycin (CLDM) for anaerobic coverage when indicated. In selected cases, single-agent therapy with sulbactam/ampicillin (SBT/ABPC), tazobactam/piperacillin (TAZ/PIPC), or meropenem (MEPM) was administered at the discretion of the operating surgeon. Although multiple antibiotic regimens were used, the overall selection strategy was consistent across the study period and between groups, reflecting routine clinical practice rather than group-specific protocols. The standard duration of antibiotic therapy was 7 days postoperatively, although adjustments were made based on intraoperative findings, the severity of postoperative symptoms, and the surgeon’s clinical judgment.

An intra-abdominal abscess was defined as the accumulation of purulent fluid in a confined space within the abdominal cavity after appendectomy, confirmed by ultrasound or computed tomography (CT) scan along with corresponding clinical and laboratory findings indicative of infection.

Statistical analysis

Data analysis was performed using JMP^® 14 (SAS Institute Inc., Cary, NC, USA). Results were expressed as mean ± standard deviation or median, as appropriate. Quantitative data were compared using Student’s t-test, and qualitative data were analyzed with Fisher’s exact test. A P value less than 0.05 was considered statistically significant.

Ethical considerations

This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by Institutional Review Board of St. Marianna University School of Medicine (No. 6656). We applied opt-out method to obtain consent on this study, and data collected was anonymized.

Results

During the study period, 63 pediatric patients underwent surgery for perforated appendicitis. One patient was excluded due to incomplete data, leaving 62 patients for analysis. Laparoscopic appendectomy was initially attempted in 61 patients. Among them, one case was converted to open surgery due to intraoperative difficulty, and one patient underwent primary open appendectomy during the early phase of laparoscopic introduction. In addition, another patient underwent open appendectomy due to concurrent coronavirus disease 2019 (COVID-19) infection, as open surgery was chosen to minimize aerosol generation. The mean age of the patients was 9.7±3.1 years, and 49 patients (79%) were male. The preoperative WBC count averaged 15,200±5,200/µL, and the CRP level was 10.0±7.5 mg/dL. Postoperative intra-abdominal abscesses developed in 7 patients (11%). Among the three patients who underwent open appendectomy—including one converted case, one during the early introduction phase of laparoscopy, and one with concurrent COVID-19 infection—only the patient with COVID-19 developed an intra-abdominal abscess. Laparoscopic appendectomy was attempted in 61 patients, while open appendectomy was performed in three patients. All open appendectomy cases were included in Group A. Among these three patients, postoperative intra-abdominal abscess developed in one case. Due to the very small number of open procedures, no statistical comparison based on surgical approach was performed. The duration of postoperative antibiotic therapy ranged from 3 to 18 days, with a median of 7 days (Table 1). Group A included 40 patients who received antibiotics for 7 days or more, while Group B included 22 patients who received antibiotics for less than 7 days. Regarding postoperative antibiotic regimens, multiple combinations and single-agent therapies were used in both groups. In Group A, the most frequently administered regimens were TAZ/PIPC (40%), FMOX-based combination therapy (47.5%), and CMZ-based therapy (10%). In Group B, TAZ/PIPC (27.3%) and FMOX-based regimens (40.9%) were most common, with smaller proportions receiving CMZ-based or carbapenem therapy. No single antibiotic regimen was overwhelmingly predominant in either group. Because of the limited sample size, statistical comparisons between individual antibiotic regimens were not performed.

Table 2 summarizes the baseline characteristics of the two groups. The mean age was 9.6±3.4 years in Group A and 9.8±2.3 years in Group B (P=0.79). There were 33 males (83%) in Group A and 16 males (73%) in Group B (P=0.52). The preoperative WBC was 14,700±5,900/µL in Group A and 16,000±3,600/µL in Group B (P=0.38). The preoperative CRP was significantly higher in Group A (11.7±8.5 mg/dL) than in Group B (7.2±4.0 mg/dL) (P=0.02). The duration of postoperative antibiotic therapy was 9.1±2.4 days in Group A and 5.2±1.1 days in Group B (P<0.001).

Postoperative intra-abdominal abscesses were diagnosed in 4 patients (10%) in Group A and in 3 patients (13%) in Group B (P=0.69). The number of patients who were diagnosed with an abscess after the cessation of antibiotics was 3 in Group A and 1 in Group B; statistical significance was not calculated because of the small sample size (Table 3). The mean time to diagnosis of an intra-abdominal abscess was 17.8±8.3 days postoperatively in Group A and 6.0±3.6 days in Group B (P=0.07). Moreover, the duration of antibiotic therapy prior to abscess diagnosis was 8.8±1.5 days in Group A and 3.7±1.2 days in Group B (P=0.005) (Table 4). With regard to postoperative antibiotic regimens, in Group A, two patients received FMOX + AMK, one patient received CMZ + AMK + CLDM, and one patient received TAZ/PIPC. In Group B, two patients received FMOX + AMK, and one patient received CMZ + AMK.

Discussion

This study found that prolonged postoperative intravenous antibiotic therapy (≥7 days) did not reduce the incidence of intra-abdominal abscess in pediatric patients with perforated appendicitis. The rate of postoperative abscess formation was comparable between the prolonged and short-course antibiotic groups. Notably, abscesses were diagnosed later in the prolonged-therapy group, suggesting that extended antibiotic use may mask early clinical signs of infection and delay diagnosis. Furthermore, the results showed that elevated preoperative CRP levels led surgeons to choose longer antibiotic courses, yet this did not translate into a reduced incidence of abscesses. These findings challenge the long-held belief that longer postoperative antibiotic therapy provides additional preventive benefit. Instead, they emphasize the importance of individualized management and careful postoperative monitoring rather than indiscriminate antibiotic prolongation.

A major strength of this study is that it provides real-world data from a single institution over a ten-year period, reflecting consistent surgical indications and postoperative management protocols. The comparison between prolonged and short-course postoperative antibiotic therapy was based on clearly defined criteria, allowing a direct assessment of whether extended antibiotic use provides additional benefit in preventing intra-abdominal abscesses. Furthermore, nearly all cases were managed laparoscopically, minimizing the influence of surgical approach on postoperative infection risk. However, several limitations of this study should be acknowledged. First, due to the retrospective design, the duration of postoperative antibiotic therapy was determined by intraoperative findings, postoperative clinical course, and the surgeon’s judgment, introducing potential selection and treatment bias. Second, postoperative antibiotic regimens were not standardized, and heterogeneity in antibiotic selection may have acted as a confounding factor. Although commonly used regimens for pediatric perforated appendicitis were employed in both groups, regimen-specific effects could not be fully evaluated. In addition, a small number of patients underwent open appendectomy or were treated during the early introduction of laparoscopic appendectomy. Although these cases were limited in number and unlikely to have substantially influenced the overall results, the potential impact of a learning-curve effect cannot be completely excluded. Therefore, the results should be interpreted as hypothesis-generating rather than definitive.

Our findings align with prior pediatric studies that question the need for prolonged postoperative antibiotics in perforated appendicitis. Fraser et al. reported in a randomized trial that shorter intravenous courses, sometimes followed by oral therapy, were not inferior to longer regimens in preventing intra-abdominal abscesses (4). In a prospective observational study, Desai et al. showed that reducing antibiotic utilization after laparoscopic appendectomy for perforated appendicitis did not increase postoperative complications (5). A narrative review by Snelling et al. also argued that the minimum effective postoperative duration can be short when adequate source control is achieved (6). Broader syntheses support a shift toward clinically guided, shorter courses. Lee et al. [American Pediatric Surgical Association (APSA) Outcomes & Clinical Trials Committee] suggested that antibiotic strategies should be individualized and criteria-based rather than time-based (7), and Rentea et al. summarized contemporary trends emphasizing stewardship in pediatric appendicitis management (2). Although focused mainly on non-perforated cases, a Cochrane review by Andersen et al. found that single-dose or short-course prophylaxis suffices for preventing postoperative infection, reinforcing the principle that more antibiotics are not necessarily better when surgical source control is adequate (8). Historical practice favored week-long or longer postoperative courses; however, outcomes research by Lelli et al. documented safe reductions in antibiotic use alongside shorter hospitalizations over time (9). In mixed or adult cohorts, Kim et al. further showed that postoperative antibiotics were not associated with fewer wound complications after appendectomy for complicated appendicitis (1). Taken together, these data are congruent with our observation that extending therapy beyond 7 days confers no additional protection against abscess formation and supports stewardship-oriented, clinically responsive protocols.

Several mechanisms may explain why prolonged postoperative intravenous antibiotic therapy did not reduce intra-abdominal abscess formation in this cohort. Extended antibiotic use can transiently suppress fever, pain, and inflammatory markers, potentially masking early signs of infection and delaying diagnostic imaging and intervention. In our data, the time to abscess diagnosis was longer in the prolonged-therapy group (P=0.07), consistent with concerns raised by Fraser et al. and the review by Snelling et al. that excessive reliance on antibiotics can obscure clinical recognition of complications (4,6). Postoperative abscesses often reflect issues of local contamination or insufficient source control rather than ongoing bacteremia amenable to prolonged systemic therapy. When adequate source control is achieved, shorter antibiotic courses appear sufficient—an approach aligned with contemporary pediatric appendicitis overviews by Rentea et al., trial evidence from Fraser et al., and broader syntheses such as the Cochrane review by Andersen et al.; in addition, consensus-style guidance from Lee et al. advocates clinically guided rather than time-locked durations (2,4,7,8). Finally, surgeons in our study tended to extend antibiotics in children with higher preoperative CRP, yet this did not translate into fewer abscesses. While our earlier work identified elevated CRP as a risk indicator for postoperative complications (10), the present findings suggest that prolongation of antibiotics alone does not mitigate that risk. Collectively, these observations support prioritizing systematic reassessment and timely imaging/drainage over routine extension of antimicrobial therapy.

The findings of this study have several important clinical implications. First, routine prolonged postoperative intravenous antibiotic therapy should be reconsidered in the management of pediatric perforated appendicitis. The results indicate that extending antibiotic administration beyond 7 days does not provide additional protection against intra-abdominal abscesses and may, in fact, delay diagnosis by masking early symptoms. Surgeons should therefore rely on objective clinical criteria—such as the resolution of fever, improvement in abdominal findings, and normalization of inflammatory markers—when determining the duration of antibiotic treatment rather than adhering to arbitrary time frames.

Second, the focus of postoperative management should shift from prevention through prolonged antibiotic use to early detection and timely treatment of abscess formation. This may include scheduled postoperative imaging or close clinical follow-up for high-risk patients, ensuring that any abscess is identified and managed promptly. Finally, these results underscore the importance of antibiotic stewardship in pediatric surgical practice. Shortening unnecessary antibiotic exposure not only reduces the risk of antimicrobial resistance but also decreases hospitalization time and medical costs, thereby improving overall patient outcomes. Future multicenter prospective studies are warranted to establish standardized, evidence-based protocols that balance infection control with the principles of responsible antibiotic use.

Conclusions

In this retrospective cohort study, prolonged postoperative intravenous antibiotic therapy was not associated with a reduced incidence of intra-abdominal abscess in pediatric patients with perforated appendicitis. These findings suggest that extending antibiotic duration beyond 7 days may not consistently confer additional benefit and highlight the importance of cautious interpretation in light of the study’s methodological limitations.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://asj.amegroups.com/article/view/10.21037/asj-2025-1-87/rc

Data Sharing Statement: Available at https://asj.amegroups.com/article/view/10.21037/asj-2025-1-87/dss

Peer Review File: Available at https://asj.amegroups.com/article/view/10.21037/asj-2025-1-87/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://asj.amegroups.com/article/view/10.21037/asj-2025-1-87/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by Institutional Review Board of St. Marianna University School of Medicine (No. 6656). We applied opt-out method to obtain consent on this study, and data collected was anonymized.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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