Incisional hernia (IH) is one of the most frequent complications encountered in daily surgical practice. It carries a substantial impact on healthcare system resources, contributes to loss of work productivity, diminishes quality of life, negatively affects body image, and is associated with pain, risk of emergency surgery, and impaired abdominal wall function [1–3]. Given this considerable burden, effective prophylaxis must be regarded as a fundamental pillar in the comprehensive management of patients undergoing abdominal surgery [4, 5].

Current clinical guidelines and meta-analysis acknowledge prophylactic mesh placement (PMP) as a safe and effective preventive intervention and advocate its consideration in patients at elevated risk for incisional hernia development [6–12]. High-quality evidence has demonstrated that, in the context of midline laparotomy, PMP significantly reduces the incidence of incisional hernia among high-risk populations, particularly in individuals with obesity and in those undergoing abdominal aortic aneurysm repair.

Despite strong evidence supporting PMP, uncertainty about its risk–benefit profile limits widespread adoption. Both surgeons and patients remain concerned about implanting mesh in the absence of a hernia, particularly regarding potential complications such as infection, seroma, or chronic pain [13–15]. Additionally, the perception that PMP prolongs operative time, together with the uncertain risk of mesh-related events, further discourages routine use and raises concerns about operating room efficiency and healthcare resource utilization [16].

Imaging is an essential adjunct in the diagnosis of incisional hernia and is increasingly important for clinical decision-making. In this study, imaging enabled assessment of abdominal wall healing and detection of potential adverse events not apparent on physical examination.

In view of the ongoing debate surrounding the advantages and potential drawbacks of mesh reinforcement, together with the challenges associated with its implementation in routine practice by general surgeons, the present multicentre study was designed to assess the use of polyvinylidene fluoride (PVDF) mesh and to adopt a widely generalizable mesh position across hospitals of varying complexity and in high-risk surgical patients and settings, including emergency procedures and contaminated fields. Our objective was to address the persistent uncertainties in this area, with particular emphasis on long-term outcomes related to the prevention of incisional hernia.

This was a prospective multicentre observational cohort study. The study report was written following the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement [17].

Prophylactic mesh reinforcement has been associated with a lower incidence of incisional hernia in high-risk patients undergoing midline laparotomy in previous studies. Under this premise, the present multicentre observational study evaluated the feasibility and outcomes of a standardized protocol for prophylactic mesh placement under real-world clinical conditions across diverse hospital settings, regardless of underlying pathology, the subspecialization of the general surgeon, the degree of surgical field contamination, and whether the procedure is performed in an elective or emergency context.

Of the initially estimated study sample, 15 patients are excluded for not meeting the inclusion criteria. Five patients who present with early postoperative abdominal wound dehiscence are excluded from the long-term analysis, as the primary objective is to evaluate the sustained outcomes of prophylactic mesh placement. This approach is further supported by the subsequent clinical course of these cases: three patients die shortly after surgery, one is managed conservatively and later dies during follow-up, and one requires reoperation with replacement of the original mesh by a different type. Under these circumstances, inclusion of these cases is considered likely to introduce substantial confounding and not to contribute meaningfully to the assessment of incisional hernia development related to prophylactic mesh, thereby potentially obscuring the long-term effects under investigation.

The inclusion of patients across the participating centres followed a similar pattern, with higher recruitment during the first year followed by a progressive decline over the study period, a finding commonly observed in long-term multicentre prospective studies [20, 21]. It may also reflect the limited adoption of prophylactic mesh in many general surgery departments, where its use remains a practice with minimal spillover across surgical services [15, 16].

The characteristics of the series reflect a high-risk patient population, with a median age of 66 years, a median body mass index of 27 kg/m², and a predominance of oncologic pathology (72.8%). This profile implies not only an increased risk of complications during hospitalization but also during follow-up, given the potential need for additional surgical procedures. Clinical contexts are likewise high risk, with 32.8% of cases performed under emergency conditions and 23.9% classified as contaminated or dirty surgery, both settings in which the systematic use of prophylactic mesh remains controversial [22]. Overall, these features represent a cohort highly representative of the complex case mix encountered in general surgery departments.

As previously reported in the short-term outcomes [23], in patients requiring reintervention, the presence of a prophylactic mesh represents an additional technical consideration; however, in most cases, access to the abdominal cavity is achieved through the mesh without major difficulty. Overall, the use of prophylactic mesh does not result in significant complications in patients requiring reoperation in either the short or long term, a finding consistent with previous studies [24], and therefore should not be regarded as a deterrent or justification for omitting its use in high-risk patients [13].

As expected with onlay PMP, seroma is relatively frequent in the early postoperative period, particularly when assessed by MRI, which likely leads to overdiagnosis, as most cases are asymptomatic and not detectable on physical examination. Although the incidence reaches approximately 20% at 6 weeks when radiological criteria are included, this rate declines markedly to 2.3% by 3 months, supporting the interpretation of seroma as a largely physiological and self-limiting response related to subcutaneous dissection and elevated body mass index rather than a clinically significant complication [11, 25]. Higher body mass index is independently associated with increased radiologically detected seroma, further reinforcing this interpretation. Other complications, such as infection, are mostly managed conservatively, and mesh removal is required in only one case, coinciding with the repair of an incisional hernia, an infrequent complication previously described in other studies [5].

Chronic abdominal wall pain was not systematically assessed beyond 3 months using a validated pain scale. However, routine clinical follow-up included the recording of postoperative events, and no patient required specific treatment or long-term analgesic medication for abdominal wall pain, nor was pain an indication for mesh removal during follow-up.

Although the expected level of radiological follow-up is not achieved, a substantial radiological dataset for assessment of the abdominal wall is obtained, with fewer than 15% of patients lacking imaging at 1 year. Several factors account for this, including the pandemic period, patient refusal to attend follow-up, and the development of additional conditions in this high-risk population. MRI-based analysis indicates no evidence of mesh contraction. More detailed evaluation of the radiological findings in this cohort is currently ongoing [26].

Based on the preventive benefit observed in reducing the incidence of incisional hernia, PMP warrants stronger consideration as part of routine abdominal wall closure in selected high-risk patients, although it is not yet established as the standard of care in international guidelines [6, 13, 27]. Among the available techniques, the onlay position appears particularly appropriate [7, 9, 28], as it combines effectiveness with technical simplicity and broad applicability, making it feasible for surgeons performing abdominal procedures across specialties, including general surgery, vascular surgery, gynecology, and urology, in diverse hospital settings. An additional advantage of this approach is that complications are generally amenable to conservative management, while the retromuscular plane is preserved, thereby maintaining optimal conditions for potential future reconstructive procedures should an incisional hernia eventually develop.

The diagnosis of incisional hernia was based on a standardized assessment combining clinical examination and radiological evaluation, supported by extensive MRI and CT follow-up. Under an intention-to-treat approach, the overall incidence of incisional hernia was 11.3%, a figure that falls within the range reported in previous studies evaluating prophylactic mesh reinforcement [29]. In the per-protocol analysis, excluding patients with early postoperative evisceration, the observed incidence was approximately 9%. Considering that nearly one-quarter of patients underwent contaminated or dirty surgery, one-third underwent emergency procedures, and radiologically detected hernias without clinical relevance were also included, these findings are consistent with those previously reported [5].

Analysis of the data identifies body mass index and stoma formation as factors predisposing to incisional hernia development, findings that are consistent with prior expectations [30–32]. Unexpectedly, longer operative time was associated with a lower incidence of incisional hernia in the multivariable analysis. Given the observational design, the wide range of operative times, and the possibility of residual confounding, this finding should be interpreted with caution and requires confirmation in future studies. Interestingly, three-quarters of the incisional hernias occurred during the first half of the study. Although the study was not designed to evaluate temporal changes in practice, this finding may reflect a more restrictive patient selection during the later stages of recruitment as participating surgeons gained experience with the protocol. Nevertheless, this observation should be interpreted with caution, as other unmeasured factors may also have contributed to the observed difference.

Most patients present with oncologic disease, in addition to other conditions that confer high surgical risk, and are managed in similarly high-risk clinical settings. This profile increases the likelihood of complications and the need for reinterventions, both during the index admission and throughout follow-up. Acceptable long-term outcomes were observed despite the complexity of this patient population.

The debate persists in that, although approximately 85% of surgeons are aware of the benefits of prophylactic mesh, only 3%–15% report routine use [15, 16]. This discrepancy remains difficult to justify, and it underscores the need to critically assess, at the time of abdominal wall closure in high-risk patients, the reasons for not implementing PMP [13, 33], rather than the converse. Hesitation is not limited to surgeons; up to 50% of patients express concerns regarding mesh implantation [14]. When additional factors such as emergency presentation or a cancer diagnosis are present, communication of the potential benefits of PMP becomes even more complex.

In our cohort, patients undergoing emergency surgery or procedures in contaminated fields did not appear to have a higher incidence of mesh-related complications. These findings suggest that prophylactic onlay PVDF mesh reinforcement is feasible in these challenging clinical settings, although confirmation in controlled comparative studies is required. Similarly, the short-term outcomes observed with PVDF mesh in the present study [23], are consistent with those reported in previous studies performed in contaminated surgical fields [34–36].

Among patients undergoing incisional hernia repair, approximately half undergo surgery concurrently for another condition, either for restoration of intestinal continuity or due to oncologic indications, indicating that a second operation would have been required regardless. This argument may be invoked both in favor of and against the use of prophylactic mesh; however, its use is likely to reduce the number of patients requiring subsequent surgery and may also be associated with the development of smaller hernias.

Several limitations should be considered. First, the absence of randomization represents a potential source of bias, including selection bias. Despite clearly defined inclusion criteria, the study period, partly overlapping with the pandemic, and the involvement of multiple centers may have contributed to a relatively limited number of enrolled cases. Furthermore, consecutive inclusion of all eligible patients could not be guaranteed, as patient enrolment also depended on surgeon participation and patient consent. The number and reasons for eligible patients who were not enrolled were not prospectively recorded, limiting the assessment of potential selection bias.

Centre imbalance represents an important limitation. One centre contributed 42.8% of the cohort but accounted for 75% of all incisional hernia events. Because only four events occurred across the remaining centres, centre-adjusted or centre-exclusion sensitivity analyses were considered unreliable. This imbalance may reflect differences in case mix and/or clinical practice and may limit the generalisability of the observed associations. This is particularly relevant to the association between stoma formation and incisional hernia, as stoma formation was also concentrated in the dominant centre.

The multivariable model included four predictors for 16 outcome events (EPV = 4), representing a substantial risk of overfitting and model-selection instability. Although Firth penalised regression and bootstrap internal validation were performed, the resulting associations should be considered exploratory and require confirmation in larger independent cohorts. Ten patients had no available follow-up information and were therefore excluded from the time-to-event analysis, leaving 170 patients for the competing-risks analysis.

In addition, the lack of a standardized fascial closure protocol left an important surgical determinant of incisional hernia uncontrolled, including the choice of suture material, needle type, suture-to-wound length ratio, and the systematic application of the small-bites technique, which may have negatively influenced the study outcomes. MRI compliance was not compared between patients with and without incisional hernia, as a detailed analysis of radiological findings and MRI follow-up is the subject of a separate dedicated manuscript currently in preparation. Moreover, validated patient-reported outcome measures were not collected, precluding a formal assessment of postoperative quality of life and patient-reported symptoms. Furthermore, sex-specific analyses were not performed because the study was not powered for subgroup comparisons according to sex.

The authors’ experience with the mesh and related speaker fees represent a potential source of bias, although these conflicts of interest were fully disclosed. Importantly, most participating surgeons had no conflicts of interest, and all statistical analyses were performed independently by a biostatistician from a public healthcare research institute with no relationship to the supporting company.

Finally, although increasing evidence supports the use of prophylactic mesh in high-risk patients, important questions remain regarding surgical site occurrences, cost–benefit considerations, quality of life, and its role in specific patient populations not represented in the present study, such as those undergoing abdominal aortic aneurysm repair.

Despite these limitations, the study has several important strengths. Its prospective design and the participation of multiple hospitals representing different levels of healthcare, enhancing the generalizability of the findings to a wide range of general surgery departments and clinical scenarios. In addition, the technique evaluated is straightforward and reproducible, even for surgeons not specifically dedicated to abdominal wall surgery. The use of MRI in combination with an iron oxide–loaded PVDF mesh further allows detailed assessment of mesh behavior after implantation. To the authors’ knowledge, no previous prospective multicentre studies have specifically addressed the use of this type of material for onlay prophylactic mesh placement regardless of the level of surgical field contamination.

In conclusion, the present study provides prospective multicentre data on the feasibility of prophylactic onlay PVDF mesh reinforcement in a heterogeneous population of high-risk patients, including emergency and contaminated procedures, with a low observed incidence of incisional hernia and acceptable mesh-related morbidity. These findings should be considered hypothesis-generating and warrant confirmation in future controlled studies.