Abdominal Wall Reconstruction With PVDF Mesh in the Setting of Active Infection

The use of synthetic mesh to repair infected defects of the abdominal wall remains controversial. This study aimed to evaluate the short-term outcomes of using PVDF mesh to treat infected abdominal wall defects in the elective setting.

From May 2016 until February 2021, 38 patients presenting with chronic mesh infection and/or enteric fistulas were enrolled in this prospective study. The active infection group (AI) was compared to a cohort of 38 patients submitted to clean ventral hernia repairs (CC). The inclusion criteria in the AI group were the presence of active chronic mesh infection (non-healing sinus, exposed mesh, or mesh-related enteric fistulas) resulting from a previous repair, or the presence of an enteric/enteroatmospheric fistula, with or without an associated abdominal wall defect. The patients invited to participate as controls had a primary or recurrent ventral hernia without previous history of infection and were eligible for clean operations. The operations in the AI group were classified as Class IV (dirty-infected), according to the CDC Wound Classifications, as adopted by the European registry for abdominal wall hernias.

The exclusion criteria were giant ventral hernias, patients on immunosuppressive or corticosteroid therapy, patients with portal hypertension, Crohn's disease, acute postoperative mesh infection, chronic infections following inguinal hernia repair, and emergency operations.

Demographic data included age, gender, American Society of Anesthesiologists (ASA) score, body mass index (BMI), comorbidities, smoking status, cancer history, and the number of previous abdominal operations. Perioperative details included the list of associated procedures, the defect width, the extension of the pre-aponeurotic dissection, operative time, and anesthesia time. Further analysis in the AI group included the clinical presentation, the onset of symptoms, the type and position of the infected mesh, the possible causes for mesh infection, and the microbiology of mesh explants.

Patients were followed and operated at the Abdominal Wall and Hernia Repair Unit at the Hospital das Clínicas, University of São Paulo, Brazil. Six surgeons of the team conducted the operations in both groups. The local ethics committee approved the study. Informed consent was obtained from all individual participants. The study was registered at the national registry, Plataforma Brasil (https://plataformabrasil.saude.gov.br/login.jsf), CAAE 52383615.0.0000.0068, and Identifier 1.412.367.

All the mesh samples used were provided by the manufacturer (FEG Textiltechnik, Aachen, Germany) through their local dealer (BMR Medical, www.bmrmedical.com.br), at no cost. None of the authors or our institution received any financial support to undertake the study.

The primary outcomes were the presence of any surgical site occurrences (SSO) or surgical site infection (SSI) during the first 30 days after the operation. The secondary outcomes included developing hernia recurrence or the recurrence of mesh infection during a 6-month follow-up period. An SSI was defined as an infection occurring where the surgery took place and was further defined as superficial, deep, and organ space. An SSO was described as any surgical infection, wound breakdown, soft tissue ischemia, seroma, and hematoma formation. A surgical site occurrence requiring procedural intervention (SSOPI) was described as any wound event requiring the opening of the wound, wound debridement, suture excision, percutaneous drainage, hematoma evacuation, or mesh removal \[14\]. The Clavien-Dindo classification \[15\] (Table 2) was applied to all surgical complications. Suspected recurrences of a hernia or infection were determined by physical examination and CT scan imaging. Non-surgical complications, other operations, and deaths were recorded during the follow-up period.

The statistical analysis was performed using the computer software Stata: version 16.0 (Stata Corp. 2019. Stata: Release 16. Statistical Software. College Station, TX: Stata Corp LLC). The frequency distribution was used by means to describe categorical variables (number of cases and relative percentage) and for continuous variables, measures of central tendency (median and mean) and variability (range and standard deviation). The nonparametric Mann-Whitney U test was applied for the statistical evaluation of the association between groups and continuous variables. The Student t-test was adopted when data normality was identified. Shapiro-Wilk test was applied to verify the normality of data. The association between categorical variables in contingency tables was analyzed using the frequency Chi-square test and the Fisher exact test adopted in 2x2 tables whenever at least one expected frequency was less than five. The 5% significance level was considered for all statistical tests.

Eligibility Criteria:
Inclusion Criteria:

* Study group: patients with the presence of an active chronic mesh infection (non-healing sinus, exposed mesh, or mesh-related enteric fistulas) resulting from a previous repair, or the presence of an enteric/enteroatmospheric fistula, with or without an associated abdominal wall defect
* Control group: patients with a primary or recurrent ventral hernia without previous history of infection and eligible for clean operations

Exclusion Criteria:

* giant ventral hernias with a volume ratio higher than 25% and loss of domicile
* patients on immunosuppressive therapy or using corticosteroids
* patients with portal hypertension
* patients with Chron´s disease
* acute postoperative mesh infection
* chronic mesh infections following inguinal hernia repair
* emergency operations.