Introduction
A hernia is a protrusion of tissue or an organ through an abnormal opening that can be primary or acquired (for example at the site of a previous surgical incision—incisional hernia) [
1,
2]. Hernias can occur in various anatomic locations, the most common being inguinal hernias [
1] followed by ventral hernias [
3].
Abdominal wall hernias can be classified into primary ventral and incisional hernias [
4]. Over 300,000 and 350,000 ventral hernia repairs are performed annually in Europe and the USA, respectively. Of these, approximately 75% are due to primary defects (mainly epigastric, umbilical, paraumbilical, and Spigelian hernias) and 25% are due to incisional hernias [
5].
Nevertheless, while both incisional and primary ventral hernias are commonly grouped, it is necessary to consider that each has a distinct pathogenesis, different patient risk factors, and therefore often different therapeutic strategies [
6].
Hernias can cause pain and discomfort that can significantly impact the quality of life of the patients. Moreover, they may lead patients to have a negative association with body image and to serious complications such as bowel incarceration [
2,
6]. Therefore, ventral hernias are usual indications for surgery and should be corrected.
Treatment of abdominal wall hernias is a rapidly evolving field of surgery, given the dramatic rise in the number of laparotomies and major surgeries being performed, the progress in anesthesiology, the increase in the number of older patients with weak connective tissue, and the increased prevalence of risk factors for hernias [
7].
Several studies showed that the costs of surgery in laparoscopic ventral hernia repair were higher when compared with the open approach because it normally requires more expensive mesh types. However, laparoscopic repair seems to be associated with fewer complications, shorter duration of hospital stay, fewer readmissions, fewer outpatient appointments, and fewer days off work than open repair. These findings can reduce post-treatment costs and might make this type of surgery more cost-efficient in comparison to open surgery [
2,
8].
The laparoscopic approach involves minimally invasive access to the abdominal cavity, and a prosthesis can be placed deep into the abdominal fascia typically without the disturbance of the hernia sac. This technique reduces the surgical insult and provides an improved view of the defect, including smaller defects that may not be identified during the clinical examination. As a result, this facilitates accurate placement of the prosthesis with reliable fascial overlap. Furthermore, it can also help to minimize the risk of bleeding, seroma formation, bowel wall injury, and infectious complications [
9].
Nevertheless, to the best of our knowledge, there are no systematic reviews only evaluating primary ventral hernia repairs, and the results of available studies and subgroup analysis remain somehow controversial, especially regarding the duration of surgery.
The primary objective of this systematic review is to compare the clinical results of the laparoscopic approach compared with the open approach of primary ventral hernias, specifically epigastric, umbilical, and paraumbilical hernias.
Methods
This systematic review and meta-analysis was executed in conformity with the “Preferred Reporting Items for Systematic Reviews and Meta-Analyses” (PRISMA) guidelines [
10].
Eligibility criteria for considering studies for this review
In this systematic review, we included all randomized controlled trials that compared the laparoscopic with the open approach in patients aged ≥ 18 years with a primary ventral hernia (specifically epigastric, umbilical, and paraumbilical hernias) who were submitted to elective repair. Studies were comprised regardless of the type of surgery, mesh type, material, placement, or method of fixation. Studies were included regardless of the year of publication, language, publication status, or sample size.
Studies that included patients with a recurrent hernia, incisional hernia, Spigelian hernia, lumbar hernia, acute or subacute intestinal obstruction, abdominal malignancies, or ascites were excluded. Patients who were submitted to emergency surgery or had more than one simultaneous surgery (for example, bariatric surgery with concomitant hernia repair) were, also, excluded.
Search method
A systematic search of MEDLINE (PubMed), Scopus, Web of Science, and Cochrane Central Register of Controlled Trials was conducted in February 2023 using the search strategies displayed in Table
1. No filters or limits were used. Furthermore, an assessment of reference bibliographies from included primary studies was performed.
Table 1
Literature search queries
MEDLINE (PubMed) | (“hernia, ventral”[MeSH] OR (hernia*[Title/Abstract] AND (ventral[Title/Abstract] OR incisional[Title/Abstract] OR epigastric[Title/Abstract] OR umbilical[Title/Abstract] OR parastomal[Title/Abstract] OR spiegel*[Title/Abstract] OR spigel*[Title/Abstract]))) AND ("laparoscopy"[ MeSH] OR laparosc*[Title/Abstract]) |
Scopus | ( TITLE-ABS-KEY ( “hernia”) AND ( TITLE-ABS-KEY ( “ventral”) OR TITLE-ABS-KEY ( “incisional”) OR TITLE-ABS-KEY ( “epigastric”) OR TITLE-ABS-KEY ( “umbilical”) OR TITLE-ABS-KEY ( “parastomal”) OR TITLE-ABS-KEY ( “spiegel*”) OR TITLE-ABS-KEY ( “spigel*”))) AND ( TITLE-ABS-KEY ( “laparoscopy”) OR TITLE-ABS-KEY ( “laparosc*”)) |
Web of Science | (ALL = (“hernia”) AND ( ALL = (“ventral”) OR ALL = (“incisional”) OR ALL = (“epigastric”) OR ALL = (“umbilical”) OR ALL = (“parastomal”) OR ALL = (“spiegel*”) OR ALL = (“spigel*”))) AND (ALL = ("laparoscopy") OR ALL = (“laparosc*”)) |
Cochrane Central Register of Controlled Trials | (“hernia, ventral”[Mesh] OR (hernia*[ti,ab,kw] AND (ventral[ti,ab,kw] OR incisional[ti,ab,kw] OR epigastric[ti,ab,kw] OR umbilical[ti,ab,kw] OR parastomal[ti,ab,kw] OR spiegel*[ti,ab,kw] OR spigel*[ti,ab,kw]))) AND ("laparoscopy"[Mesh] OR laparosc*[ti,ab,kw]) |
Selection of studies
The title and the abstract of all the studies identified by the search strategy were independently screened for potential eligibility by two reviewers (MM and MV). Disagreements were solved by meeting and debating with a third reviewer (HS) to reach a consensus. Subsequently, the full texts of articles not excluded in the previous stage were thoroughly independently reviewed by the same reviewers (MM and MV) and checked against the inclusion criteria. When different articles corresponding to the same study were found, only the latest was included.
Data collection
Data collection was executed by one reviewer (MM) and checked by a second reviewer (MV). Data extracted from the studies consisted of the study design, sample size, description of the surgery approach, duration of surgery, follow-up period, and outcomes measured. The main assessed outcome was hernia recurrence. Additional outcomes included the duration of surgery, length of hospital stay, time until return to work, and surgery complications such as seroma, wound dehiscence, local infection, and postoperative pain. The collected data were entered and managed in RevMan 5 Software [
11].
In the presence of incongruencies and missing data in primary studies, we contacted the authors to try to obtain the correct information. If that was not possible, the data was collected and analyzed according to the description of the methods and results given by the authors, not by the statistical analysis.
Risk of bias assessment
The quality (risk of bias (RoB)) of included studies was independently evaluated by two reviewers (MM and MV) according to the Cochrane RoB2 tool regarding the randomization process, intended intervention, missing outcome data, measurement of the outcome, and selection of the reported result [
12,
13]. Subsequently, the data from the evaluation of bias was summarized using the robvis tool [
14].
Data analysis
All the results that were measured on the same scale or could be converted to the same units were included in the meta-analysis. For studies that evaluated a determined outcome more than once only the latest evaluation was taken into account, for example, if a study evaluated pain at 2 h and 24 h post-surgery, only the 24-h measure was considered.
Furthermore, if studies compared more than one type of laparoscopic approach with the open approach, we independently analyzed both techniques with the open approach.
Risk ratios (RR) were calculated for all the dichotomous outcomes using 95% confidence intervals (CI). Continuous outcomes reported in the parametric form (mean with standard deviation) were evaluated and presented as weighted mean differences (MD). If standard deviations for continuous outcome data were not available, we estimated its value from the standard error of the mean, when feasible.
The
I2 statistic was calculated to quantify the heterogeneity. An
I2 inferior to 25% corresponded to minimal or no heterogeneity, an
I2 between 25 and 50% was related to mild to moderate, an
I2 within 50 to 75% correlated to moderate to substantial, and an
I2 superior to 75% was associated with substantial to maximum heterogeneity [
15]. In the presence of substantial heterogeneity (
I2 > 50% and
p-value < 0.10) we performed a random-effects meta-analysis. Otherwise, the fixed-effects model was used.
A leave-one-out sensitivity analysis was performed when the heterogeneity was substantial. Graphical display by funnel plots was used to evaluate the presence of publication bias. Meta-regression and subgroup analysis were not performed on account of the small number of primary studies included.
Discussion
Recent studies concluded that primary and incisional ventral hernias were statistically significantly different for almost all patients regarding hernias, surgical, and postoperative characteristics. Furthermore, they say that given these differences, data on primary hernias, and incisional hernias should not be pooled in studies reporting on hernia repair [
5,
60].
Regarding these new findings, we conducted this systemic review and meta-analysis that, unlike similar previous systematic reviews [
4,
9,
34,
61], to the best of our knowledge, was the first one to solely evaluate patients with the diagnosis of primary ventral hernia.
A total of nine studies were included in the meta-analysis. The meta-analysis results revealed that the overall hernia recurrence, local infection, wound dehiscence, and local seroma were significantly less likely to be present in a patient who underwent the laparoscopic approach. These findings go alongside the expected based on previous studies. Although the heterogeneity between studies was non-existent or mild, the results should be analyzed carefully as all the included studies had some or a high risk of bias and did not specify how the outcomes were evaluated.
The data on postoperative pain, length of hospital stay, and time until return to work were substantially heterogeneous. However, the laparoscopic approach seemed beneficial in all the included studies.
Regarding the duration of surgery, there was a lot of controversy across the studies. This heterogeneity could be justified by the presence of a learning curve in the laparoscopic repair, by the time required for handling the mesh, or by adversities that could be found during the surgery and could influence the duration of the surgery. The authors of Elashry et al
. [
52] concluded that the significant difference in prolongation of the time in IPOM plus was due to handling the mesh intra-peritoneally, but with experience, this difficulty could be overcome. Al-Mulhim et al
. [
62] and Nijas et al
. [
63] also concluded that the time for laparoscopic repair decreased with the progress in the learning curve.
Assessing the limitations of this systematic review and meta-analysis, firstly, it should be noted that the included studies, which were all randomized controlled trials, had some concerns regarding the allocation of the patients, and the methods used were not well described which could lead to serious bias.
Secondly, this systematic review and meta-analysis included a small number of studies in which the type of hernia and surgical approach varied between studies. In these cases, a subgroup analysis could be beneficial, due to the small number of included primary studies that was not feasible.
Also, the included studies had, in general, small sample sizes, and two studies [
56,
59] had missing data and a combined total of 23 laparoscopies that were converted to open surgeries and analyzed as such (intention-to-treat analysis). These characteristics of primary included studies could have some implications on the interpretation of the results because they could lead to heterogeneity and bias.
Furthermore, the included studies had a follow-up period of 2 years or less, and, in the majority of studies, the hernia size was 4 cm or less. These could lead to a smaller number of reported hernia recurrences and other complications. Additionally, hernia size could be a confounder in some of the outcomes, such as seroma and hernia recurrence.
In order to identify if any individual study was associated with higher heterogeneity, a leave-on-out sensitivity analysis was made. Regarding postoperative pain, the exclusion of Khan et al
. [
54] was associated with a reduction of heterogeneity from 99 to 9%. These could be related to the fact that Khan et al
. [
54] included epigastric, umbilical, and paraumbilical hernias, while Elashry et al
. [
52] only included paraumbilical hernias and Purushotham and Madhu [
51] umbilical and paraumbilical hernias.
Moreover, the exclusion of Purushotham and Madhu [
51] was related to a complete reduction of the heterogeneity in time until the return to work, which could be justified by the different hernia types included in the individual studies and the small number of primary studies included in the meta-analysis.
Regarding the potential influence of publication bias on the results of this systematic review and meta-analysis, although it was difficult to evaluate its specific impact due to the small number of included primary studies in each outcome, it can be considered small. An extensive literature search was executed; therefore, it is unlikely that important randomized controlled trials were not identified by the initial search.
The overall treatment of primary ventral hernias appeared to be more beneficial in terms of clinical outcomes in the laparoscopic approach. Nonetheless, the published guidelines only recommend the laparoscopic approach in specific patients [
7,
8].
In this regard, it is worth mentioning that, although our meta-analysis suggests that laparoscopic surgery in primary ventral hernia repair is beneficial and advantageous, this study is not free of limitations and some aspects (duration of surgery, hernia recurrence, and post-operative pain) need to be studied in more detail to help direct future research and development of specific guidelines for primary ventral hernia repair as an independent entity.
Conclusion
Currently, the results of available studies for the treatment of patients with primary ventral hernia remain somewhat controversial and with low-quality evidence. Even though all the studies are randomized controlled trials, the majority have a high risk of bias, few results, scarce samples, and few outcomes assessed and don’t have well-defined protocols (no sample size calculation, no primary outcome defined, and do not specify the methods used to assess the outcomes).
Though the available evidence is weak and the existing studies have low quality, we assume that the laparoscopic approach of the primary ventral hernia repair seems beneficial concerning hernia recurrence, local infection, wound dehiscence, and local seroma. Additionally, it seemed to improve the postoperative pain, length of hospital stay, and time until return to work. However, this is yet to be proven.
Further and larger studies are needed, namely randomized controlled trials, methodologically well executed, with an adequate number of participants, and a sufficient follow-up period before definitive conclusions on the true value of this procedure can be derived in order to allow confirmation of these results.
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.