Randomized clinical trials comparing antibiotic therapy with appendicectomy for uncomplicated acute appendicitis: meta-analysis

Three-Year Outcomes of Oral Antibiotics vs Intravenous and Oral Antibiotics for Uncomplicated Acute Appendicitis: A Secondary Analysis of the APPAC II Randomized Clinical Trial

Importance

Current short-term evidence has shown that uncomplicated acute appendicitis can be treated successfully with oral antibiotics alone, but longer-term results are lacking.

Objective

To assess the treatment effectiveness of oral antibiotic monotherapy compared with combined intravenous (IV) and oral antibiotics in computed tomography-confirmed uncomplicated acute appendicitis at a longer-term follow-up.

Design, Setting, and Participants

This secondary analysis of a predefined year 3 follow-up of the Appendicitis Acuta II (APPAC II) noninferiority, multicenter randomized clinical trial compared oral moxifloxacin with combined IV ertapenem plus oral levofloxacin and metronidazole for the treatment of uncomplicated acute appendicitis. The trial was conducted at 9 university and central hospitals in Finland from April 2017 to November 2018, with the last follow-up in November 2022. Participants included patients aged 18 to 60 years, who were randomized to receive either oral antibiotics monotherapy (n = 301) or combined IV and oral antibiotics (n = 298).

Interventions

Antibiotics monotherapy consisted of oral moxifloxacin, 400 mg/d, for 7 days. Combined IV and oral antibiotics consisted of IV ertapenem sodium, 1 g/d, for 2 days plus oral levofloxacin, 500 mg/d, and metronidazole, 500 mg 3 times/d, for 5 days.

Main Outcomes and Measures

The primary end point was treatment success, defined as the resolution of acute appendicitis and discharge from hospital without the need for surgical intervention and no appendicitis recurrence at the year 3 follow-up evaluated using a noninferiority design. The secondary end points included late (after 1 year) appendicitis recurrence as well as treatment-related adverse events, quality of life, length of hospital stay, and length of sick leave, which were evaluated using a superiority design.

Results

After exclusions, 599 patients (mean [SD] age, 36 [12] years; 336 males [56.1%]) were randomized; after withdrawal and loss to follow-up, 582 patients (99.8%) were available for the year 3 follow-up. The treatment success at year 3 was 63.4% (1-sided 95% CI, 58.8% to ∞) in the oral antibiotic monotherapy group and 65.2% (1-sided 95% CI, 60.5% to ∞) in the combined IV and oral antibiotics group. The difference in treatment success rate between the groups at year 3 was -1.8 percentage points (1-sided 95% CI, -8.3 percentage points to ∞; P = .14 for noninferiority), with the CI limit exceeding the noninferiority margin. There were no significant differences between groups in treatment-related adverse events, quality of life, length of hospital stay, or length of sick leave.

Conclusions and Relevance

This secondary analysis of the APPAC II trial found a slightly higher appendectomy rate in patients who received oral antibiotic monotherapy; however, noninferiority of oral antibiotic monotherapy compared with combined IV and oral antibiotics could not be demonstrated. The results encourage future studies to assess oral antibiotic monotherapy as a viable treatment alternative for uncomplicated acute appendicitis.

Trial Registration

ClinicalTrials.gov Identifier: NCT03236961.

Implementation of artificial intelligence-based computer vision model in laparoscopic appendectomy: validation, reliability, and clinical correlation

BACKGROUND

Application of artificial intelligence (AI) in general surgery is evolving. Real-world implementation of an AI-based computer-vision model in laparoscopic appendectomy (LA) is presented. We aimed to evaluate (1) its accuracy in complexity grading and safety adherence, (2) clinical correlation to outcomes.

METHODS

A retrospective single-center study of 499 consecutive LA videos, captured and analyzed by 'Surgical Intelligence Platform,' Theator Inc. (9/2020-5/2022). Two expert surgeons viewed all videos and manually graded complexity and safety adherence. Automated annotations were compared to surgeons' assessments. Inter-surgeons' agreements were measured. Since 7/2021 videos were linked to patients' admission numbers. Data retrieval from medical records was performed (n = 365). Outcomes were compared between high and low complexity grades.

RESULTS

Low and high complexity grades comprised 74.8 and 25.2% of 499 videos. Surgeons' agreements were high (76.9-94.4%, kappa 0.77/0.91; p < 0.001) for all annotated complexity grades. Surgeons' agreements were also high (96.0-99.8%, kappa 0.78/0.87; p < 0.001) for full safety adherence, whereas agreement was moderate in partial safety adherence and none (32.8-58.8%). Inter-surgeons' agreements were high for complexity grading (kappa 0.86, p < 0.001) and safety adherence (kappa 0.88, p < 0.001). Comparing high to low grade complexity, preoperative clinical features were similar, except larger appendix diameter on imaging (13.4 ± 4.4 vs. 10.5 ± 3.0 mm, p < 0.001). Intraoperative outcomes were significantly higher (p < 0.001), including time to achieve critical view of safety (29.6, IQR 19.1-41.6 vs. 13.7, IQR 8.5-21.1 min), operative duration (45.3, IQR 37.7-65.2 vs. 25.0, IQR 18.3-32.7 min), and intraoperative events (39.4% vs. 5.9%). Postoperative outcomes (7.4% vs. 9.2%) including surgical complications, mortality, and readmissions were comparable (p = 0.6), except length of stay (4, IQR 2-5.5 vs. 1, IQR 1-2 days; p < 0.001).

CONCLUSION

The model accurately assesses complexity grading and full safety achievement. It can serve to predict operative time and intraoperative course, whereas no clinical correlation was found regarding postoperative outcomes. Further studies are needed.

Appendectomy versus antibiotic treatment for acute appendicitis

BACKGROUND

Acute appendicitis is one of the most common emergency general surgical conditions worldwide. Uncomplicated/simple appendicitis can be treated with appendectomy or antibiotics. Some studies have suggested possible benefits with antibiotics with reduced complications, length of hospital stay, and the number of days off work. However, surgery may improve success of treatment as antibiotic treatment is associated with recurrence and future need for surgery.

OBJECTIVES

To assess the effects of antibiotic treatment for uncomplicated/simple acute appendicitis compared with appendectomy for resolution of symptoms and complications.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and two trial registers (World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov) on 19 July 2022. We also searched for unpublished studies in conference proceedings together with reference checking and citation search. There were no restrictions on date, publication status, or language of publication.

SELECTION CRITERIA

We included parallel-group randomised controlled trials (RCTs) only. We included studies where most participants were adults with uncomplicated/simple appendicitis. Interventions included antibiotics (by any route) compared with appendectomy (open or laparoscopic).

DATA COLLECTION AND ANALYSIS

We used standard methodology expected by Cochrane. We used GRADE to assess the certainty of evidence for each outcome. Primary outcomes included mortality and success of treatment, and secondary outcomes included number of participants requiring appendectomy in the antibiotic group, complications, pain, length of hospital stay, sick leave, malignancy in the antibiotic group, negative appendectomy rate, and quality of life. Success of treatment definitions were heterogeneous although mainly based on resolution of symptoms rather than incorporation of long-term recurrence or need for surgery in the antibiotic group.

MAIN RESULTS

We included 13 studies in the review covering 1675 participants randomised to antibiotics and 1683 participants randomised to appendectomy. One study was unpublished. All were conducted in secondary care and two studies received pharmaceutical funding. All studies used broad-spectrum antibiotic regimens expected to cover gastrointestinal bacteria. Most studies used predominantly laparoscopic surgery, but some included mainly open procedures. Six studies included adults and children. Almost all studies aimed to exclude participants with complicated appendicitis prior to randomisation, although one study included 12% with perforation. The diagnostic technique was clinical assessment and imaging in most studies. Only one study limited inclusion by sex (male only). Follow-up ranged from hospital admission only to seven years. Certainty of evidence was mainly affected by risk of bias (due to lack of blinding and loss to follow-up) and imprecision. Primary outcomes It is uncertain whether there was any difference in mortality due to the very low-certainty evidence (Peto odds ratio (OR) 0.51, 95% confidence interval (CI) 0.05 to 4.95; 1 study, 492 participants). There may be 76 more people per 1000 having unsuccessful treatment in the antibiotic group compared with surgery, which did not reach our predefined level for clinical significance (risk ratio (RR) 0.91, 95% CI 0.87 to 0.96; I2 = 69%; 7 studies, 2471 participants; low-certainty evidence). Secondary outcomes At one year, 30.7% (95% CI 24.0 to 37.8; I2 = 80%; 9 studies, 1396 participants) of participants in the antibiotic group required appendectomy or, alternatively, more than two-thirds of antibiotic-treated participants avoided surgery in the first year, but the evidence is very uncertain. Regarding complications, it is uncertain whether there is any difference in episodes of Clostridium difficile diarrhoea due to very low-certainty evidence (Peto OR 0.97, 95% CI 0.24 to 3.89; 1 study, 1332 participants). There may be a clinically significant reduction in wound infections with antibiotics (RR 0.25, 95% CI 0.09 to 0.68; I2 = 16%; 9 studies, 2606 participants; low-certainty evidence). It is uncertain whether antibiotics affect the incidence of intra-abdominal abscess or collection (RR 1.58, 95% CI 0.61 to 4.07; I2 = 19%; 6 studies, 1831 participants), or reoperation (Peto OR 0.13, 95% CI 0.01 to 2.16; 1 study, 492 participants) due to very low-certainty evidence, mainly due to rare events causing imprecision and risk of bias. It is uncertain if antibiotics prolonged length of hospital stay by half a day due to the very low-certainty evidence (MD 0.54, 95% CI 0.06 to 1.01; I2 = 97%; 11 studies, 3192 participants). The incidence of malignancy was 0.3% (95% CI 0 to 1.5; 5 studies, 403 participants) in the antibiotic group although follow-up was variable. Antibiotics probably increased the number of negative appendectomies at surgery (RR 3.16, 95% CI 1.54 to 6.49; I2 = 17%; 5 studies, 707 participants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

Antibiotics may be associated with higher rates of unsuccessful treatment for 76 per 1000 people, although differences may not be clinically significant. It is uncertain if antibiotics increase length of hospital stay by half a day. Antibiotics may reduce wound infections. A third of the participants initially treated with antibiotics required subsequent appendectomy or two-thirds avoided surgery within one year, but the evidence is very uncertain. There were too few data from the included studies to comment on major complications.

Incidence and clinical features of endometriosis in 2484 consecutive female patients undergoing appendectomy for suspected appendicitis-a retrospective analysis

INTRODUCTION

Endometriosis is a common condition affecting 5 to 10% of women of childbearing age. The true incidence of endometriosis of the appendix is currently unknown. Since symptoms often overlap with those of acute appendicitis, endometriosis of the appendix presents a diagnostic challenge in the emergency department. This large retrospective study investigates the incidence and perioperative clinical, radiologic, and laboratory findings, as well as possible differences between patients with and without endometriosis.

METHODS

Data from consecutive patients who underwent appendectomy for suspected appendicitis without a history of endometriosis were analyzed. Perioperative clinical, laboratory, perioperative, and histopathologic findings were compared between women with and without endometriosis.

RESULTS

Between January 2008 and June 2023, 2484 consecutive patients without a history of endometriosis underwent urgent appendectomy for suspected appendicitis. Endometriosis was detected on histopathologic examination in 17 (0.7%) patients. Signs of appendicitis were found less frequently on ultrasound in the endometriosis group compared to the non-endometriosis group (23.4% vs. 61.5%; p = 0.002; OR = 0.193; 95% CI 0.063-0.593). There were no differences in physical examination findings, duration of symptoms, degree of inflammation, surgical outcomes, or complication rates.

CONCLUSION

The incidence of endometriosis of the appendix in patients undergoing appendectomy for suspected appendicitis was higher than suggested by data from autopsy series and populations with biopsy-proven endometriosis. Patients with endometriosis of the appendix were less likely to have a positive ultrasound finding, but perioperative and histopathologic findings and severity of inflammation did not differ from patients without endometriosis, presenting diagnostic challenges for clinicians.

Acute appendicitis: A block-randomized study on active observation with or without antibiotic treatment

BACKGROUND

Antibiotic treatment of unselected patients with acute appendicitis is safe and effective. However, it is unknown to what extent early provision of antibiotic treatment may represent overtreatment due to spontaneous healing of appendix inflammation. The aim of the present study was to evaluate the role of antibiotic treatment versus active in-hospital observation on spontaneous regression of acute appendicitis.

METHOD

Patients who sought acute medical care at Sahlgrenska University Hospital were block-randomized according to age (18-60 years) and systemic inflammation (C-reactive protein <60 mg/L, white blood cell <13,000/μL), in combination with clinical and abdominal characteristics of acute appendicitis. Study patients received antibiotic treatment and active observation, while control patients were allocated to classic active "wait and see observation" for either disease regression or the need for surgical exploration. According to our standard surgical care, certified surgeons in charge decided whether and when appendectomy was necessary. In total, 1,019 patients were screened for eligibility; 203 patients met inclusion criteria, 126 were accepted to participate, 29 declined, and 48 were missed for inclusion.

RESULTS

The antibiotic group (n = 69) and the control group (n = 57) were comparable at inclusion. Appendectomy at first hospital stay was 28% and 53% for study and control patients (χ2, P < .004). Life table analysis indicated a time-dependent difference in the need for appendectomy during follow-up (P < .03). Antibiotics prevented surgical exploration and appendectomy by 72% to 50% compared to 47% to 37% in the control group across the time course follow-ups between 5 and 1,200 days.

CONCLUSION

Early antibiotic treatment is superior to traditional "wait and see observation" to avoid surgical exploration and appendectomy.

Appendicolith appendicitis: should we be operating sooner? A retrospective cohort study

INTRODUCTION

Evidence suggests that delaying an appendicectomy for up to 24 hours does not increase the risk of complicated appendicitis. Appendicoliths are a risk factor for perforation. No study has explored the temporal relationship between appendicolith presence and time to perforation. In this retrospective cohort study, we hypothesise that the presence of an appendicolith confirmed on preoperative computerised tomography scan (pCT) leads to a shorter time to complicated appendicitis.

METHODS

We undertook a retrospective single-centre study of patients admitted between 2018 and 2020. Inclusion criteria included: age ≥18 years, appendicitis confirmed on histopathology following an operation and a pCT scan. Complicated appendicitis was defined intraoperatively as an appendicular abscess, gangrenous or perforated appendix.

RESULTS

Some 310 patients were included in the study. Forty-five per cent presented with complicated appendicitis (n = 138). Appendicoliths were present in 79 (25.5%) patients. Multivariate logistic regression identified an appendicolith as a significant risk factor for perforation (odds ratio 3.50, 95% confidence interval [CI] 1.16-10.59; p = 0.027). Within the first 12 hours of admission, patients with an appendicolith accounted for a significantly greater proportion of those with complicated appendicitis intraoperatively compared with those without (56.7% vs 43.3%, respectively; p = 0.003). Within 12 hours of admission, those with an appendicolith were 2.05 times more likely to suffer from complicated appendicitis than those without (95% CI 1.28-3.29).

CONCLUSIONS

Patients with an appendicolith appendicitis should be considered for an early appendicectomy. Future large-scale multicentre prospective studies are required to explore this further, perhaps informing future guidelines.

A recurrent retrohepatic abscess secondary to a dropped appendicolith

Appendicoliths can drop into the peritoneal cavity during the course of an appendicectomy, or more commonly as a result of perforated appendicitis. We report the case of a patient with a history of recurrent retrohepatic abscesses over 7-year period due to a retained appendicolith and review the literature on perihepatic abscesses caused by retained appendicoliths. The abscess had been drained percutaneously 4 times without retrieval of the appendicolith and eventually the patient needed a laparotomy, drainage of the abscess, and extraction of the appendicolith. Treatment of abscesses secondary to dropped appendicoliths may be percutaneous, laparoscopic, or via conventional open surgery, but it is important to retrieve the appendicolith if recurrent abscess formation is to be avoided.

Outcome of Laparoscopic Versus Open Appendectomy for Acute Appendicitis-Results of a Propensity Score Matching Analysis of 542 Patients and Consequences for the Military Surgeon

INTRODUCTION

Appendectomy is the treatment of choice for acute appendicitis. The procedure can be performed open or laparoscopically. However, laparoscopy is not available on military missions abroad. It is unclear whether treatment outcomes differ between the two surgical approaches.

MATERIALS AND METHODS

Treatment data of all patients undergoing open and laparoscopic appendectomies in the German Armed Forces Hospital of Ulm from 2013 to 2017 were collected retrospectively. A propensity score matching analysis was performed to minimize the influence of potential confounders and to assess the influence of surgical approach on outcome (reoperations, superficial and deep surgical infections, length of postoperative ileus, need for intravenous analgesics, and operative time).

RESULTS

A total of 542 patients with complete datasets were included in the propensity score matching analysis, among these 64 with open and 478 laparoscopic procedures. There were no statistically significant differences between open and laparoscopic surgeries with respect to all outcome variables, with the exception of a 25-minute prolonged operative time for the open approach.

CONCLUSIONS

Open appendectomy can be considered equivalent in outcome to the laparoscopic procedure and thus can be performed on military missions abroad without compromising outcome. Military surgeons must continue to be trained and confident in open appendectomy.

A meta-analysis and trial sequential analysis comparing nonoperative versus operative management for uncomplicated appendicitis: a focus on randomized controlled trials

BACKGROUND

The aim of this study is to provide a meta-analysis of randomized controlled trials (RCT) comparing conservative and surgical treatment in a population of adults with uncomplicated acute appendicitis.

METHODS

A systematic literature review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive search was conducted in MEDLINE, Embase, and CENTRAL. We have exclusively incorporated randomized controlled trials (RCTs). Studies involving participants with complicated appendicitis or children were excluded. The variables considered are as follows: treatment complications, complication-free treatment success at index admission and at 1 year follow-up, length of hospital stay (LOS), quality of life (QoL) and costs.

RESULTS

Eight RCTs involving 3213 participants (1615 antibiotics/1598 appendectomy) were included. There was no significant difference between the two treatments in terms of complication rates (RR = 0.66; 95% CI 0.61-1.04, P = 0.07, I2 = 69%). Antibiotics had a reduced treatment efficacy compared with appendectomy (RR = 0.80; 95% CI 0.71 to 0.90, p < 0.00001, I2 = 87%) and at 1 year was successful in 540 out of 837 (64.6%, RR = 0.69, 95% confidence interval 0.61 to 0.77, p < 0.00001, I2 = 81%) participants. There was no difference in LOS (mean difference - 0.58 days 95% confidence interval - 1.59 to 0.43, p = 0.26, I2 = 99%). The trial sequential analysis has revealed that, concerning the three primary outcomes, it is improbable that forthcoming RCTs will significantly alter the existing body of evidence.

CONCLUSIONS

As further large-scale trials have been conducted, antibiotic therapy proved to be safe, less expensive, but also less effective than surgical treatment. In order to ensure well-informed decisions, further research is needed to explore patient preferences and quality of life outcomes.

Laparoscopic Appendectomy Combined with an "Antimicrobial-Free" Strategy for Acute Uncomplicated Appendicitis

Objective: To explore the efficacy and safety of enhanced recovery protocol (ERP) combined with laparoscopic appendectomy (LA) in the treatment of acute uncomplicated appendicitis (AUA) without antibiotics. Methods: In this study, a total of 160 patients with AUA who underwent LA between January 2018 and December 2021 were included and divided into the antibiotic group (n = 80) or the no-antibiotic group (n = 80). The patients in the antibiotic group received the ERP combined with antimicrobials during the perioperative period, while those in the no-antibiotic group only received the ERP during the perioperative period. The clinical data of these patients were collected to compare the inflammation level and stress state before and after surgery. In addition, the incidence of postoperative complications and the recovery speed of the patients were compared between groups. Results: There were no significant differences in the inflammation level and stress state before or after surgery, the incidence of postoperative complications or the recovery speed between the antibiotic group and the no-antibiotic group (P > .05). Conclusion: The use of ERP combined with LA as an antimicrobial-free treatment scheme in the perioperative period was found to be safe and effective for patients with AUA. Therefore, this approach is clinically valuable.

The Vermiform Appendix and Its Pathologies

The vermiform appendix is a muscular cylindrical structure originating near the junction of the cecum and ileum, averaging 9 cm (5-35 cm) in size. As the most mobile viscera, it can adopt several positions, the most common being the retrocecal position. Perceived as an atavistic organ lacking physiological relevance, the vermiform appendix appears to be involved in immune function, serving in the maturation of B lymphocytes and the production of immunoglobulin A, in endocrine function, excreting amines and hormones in the 2-3 mL of mucus secreted daily, and in digestive function, by storing beneficial bacteria from where they can recolonize the colon. With a lumen of about 6 mm, the vermiform appendix has a reduced storage capacity, so any blockage of the appendix with fecoliths (fecaliths), seeds derailed from the colon, or enlarged lymph nodes prevents drainage and intraluminal accumulation of secreted mucus. Unable to relax, the appendix wall severely limits its intraluminal volume, so mucus accumulation leads to inflammation of the appendix, known generically as appendicitis. In addition, the vermiform appendix may be the site of the development of neoplastic processes, which may or may not involve mucus production, some of which can significantly affect the standard of living and ultimately lead to death. In general, mucinous tumors may have a better prognosis than non-mucinous tumors. This review takes a comprehensive path, starting by describing the anatomy and embryology of the vermiform appendix and further detailing its inflammatory pathologies, pathologies related to congenital anomalies, and appendix tumors, thus creating an up-to-date framework for better understanding, diagnosis, and treatment of these health problems.

Three Centuries of Appendicectomy

BACKGROUND

Save for the contribution of Charles McBurney, who described his eponymous point and the appendicectomy incision, the history of appendicectomy is largely unknown among the medical profession. This review traces the history from the first anatomical depiction of the appendix to the development of open appendicectomy and the recent minimally invasive and non-operative methods.

METHODS

Historical articles, monographs and books containing anatomical descriptions of the vermiform appendix and reports of appendicitis and its surgical treatment were retrieved after searching the PubMed, Google Scholar and Embase databases from their inception to 31 March 2022.

RESULTS

The first inadvertent appendicectomy was performed during an operation for a groin hernia by Cookesley in 1731, and Mestivier was the first to drain a right iliac fossa abscess, due to appendicitis, in 1757. Krönlein performed the first appendicectomy for acute appendicitis in 1884 but his patient died. The first successful appendicectomy for acute appendicitis leading to patient survival was by Morton in 1887. In 1976, Wirschafter and Kaufman performed an inadvertent colonoscopic appendicectomy and, in 1980, Semm carried out the first laparoscopic appendicectomy. The first appendicectomy via a natural orifice (transgastric) appendicectomy was by Rao and Reddy in 2004.

CONCLUSION

This historical review charts the development of surgical knowledge concerning the management of appendicitis, from the first anatomical drawings of the appendix and descriptions of appendicitis to the development of surgical and conservative treatments up to the present day. It also corrects some inaccuracies of attribution in previous historical reviews.

Typical and Atypical Presentations of Appendicitis and Their Implications for Diagnosis and Treatment: A Literature Review

Appendicitis, an acute inflammation of the appendix, affects all demographic groups and exhibits various incidences and clinical manifestations. While acute appendicitis typically presents with colicky periumbilical abdominal pain that localizes to the right lower quadrant, atypical presentations are more common in children, geriatric, and pregnant patient populations, leading to delays in diagnosis. Clinical evaluation, clinical scoring systems, and inflammatory markers are commonly used, but their limitations have led to the increased use of diagnostic imaging in patients suspected of appendicitis. Acute appendicitis is managed by non-operative and operative management, depending on whether it is uncomplicated or complicated. Developing diagnostic pathways to improve outcomes and reduce complications is crucial. Although medical advancements have been made, diagnosing and managing appendicitis can be challenging, mainly when patients are present atypically. This literature review aims to comprehensively review typical and atypical presentations of appendicitis and their current implications for diagnosis and treatment modalities in pediatric, adult, pregnant, and geriatric patient populations.

IL-5 Serum and Appendicular Lavage Fluid Concentrations Correlate with Eosinophilic Infiltration in the Appendicular Wall Supporting a Role for a Hypersensitivity Type I Reaction in Acute Appendicitis

Appendicitis is the most common abdominal surgical emergency, but its aetiology is not fully understood. We and others have proposed that allergic responses play significant roles in its pathophysiology. Eosinophils and Interleukin (IL)-5 are involved in a hypersensitivity type I reaction. Eosinophil infiltration is common in the allergic target organ and is dependent on IL-5. In the presence of an allergic component, it is expected that the eosinophil count and IL-5 local and systemic concentrations become elevated. To address this hypothesis, we designed a prospective study that included 65 patients with acute appendicitis (grouped as acute phlegmonous or gangrenous according to the histological definition) and 18 patients with the clinical diagnosis of acute appendicitis, but with normal histological findings (control group) were enrolled. Eosinophil blood counts and appendicular wall eosinophil infiltration were determined. IL-5 levels in blood and appendicular lavage fluid were evaluated. Appendicular lavage fluid was collected by a new methodology developed and standardized by our group. Appendicular wall eosinophil infiltration was higher in acute phlegmonous appendicitis than in gangrenous appendicitis (p = 0.000). IL-5 blood levels were similar in both pathologic and control groups (p > 0.05). In the appendicular lavage fluid, the higher levels of IL-5 were observed in the phlegmonous appendicitis group (p = 0.056). We found a positive correlation between the appendicular wall eosinophilic infiltration and the IL-5 concentrations, in both the blood and the appendicular lavage fluid, supporting the IL-5 reliance in eosinophil local infiltration. We observed the highest presence of eosinophils at phlegmonous appendicitis walls. In conclusion, the present data are compatible with a hypersensitivity type I allergic reaction in the target organ, the appendix, during the phlegmonous phase of appendicitis.