Laparoendoscopic extraperitoneal surgical techniques for ventral hernias and diastasis recti repair: a systematic review

Minimally invasive abdominal surgery was born the ‘90s with the introduction of IPOM technique [5]. In this case the mesh is positioned as a sort of barrier that covers the defect avoiding the possibility of hernia incarceration, there is no reconstruction of the abdominal wall, which instead occurs in the case of IPOM+, that involves the suture of the defect before mesh placement. Currently, it would seem more correct to indicate the IPOM technique with the acronym IPUM, replacing the O for onlay, a historical legacy of the first acronym, with the U for underlay, because the mesh indicated today as onlay is positioned underneath over the muscles. The LIRA technique, recently proposed by the group of Dr. Salvador Morales-Conde, involves the incision and medial plication of the posterior rectus sheath to reconstruct the closure of the defect and the subsequent positioning of the mesh [22]. Compared to the other techniques, the LIRA reduces tension on the suture line, determines the adhesion of the mesh directly in contact with the muscle, and seems to guarantee greater grip of the same with less possibility of detachment.

However, these approaches have an increased risk of adhesions, bowel injuries and mesh-related complications, such as infection, migration, or seroma formation, due to the intraperitoneal mesh positioning and fixation [23, 24]. Moreover, increased postoperative pain [25], and higher reoperation rates have also been described [26].

Ventral TAPP is a transperitoneal approach proposed to overcome the limitations of intraperitoneal techniques. In fact, in a recent metanalysis, it was associated with considerable benefits when compared to IPOM: ventral TAPP was less painful and presented reduced average cost and decreased SSI. However, ventral TAPP and IPOM did not show any difference in terms of intraoperative complications, recurrence rate and chronic pain [20].

So, to overcome the limitations of these techniques, extraperitoneal approaches have been proposed during the last years.

The main advantage of the posterior extraperitoneal approach is to perform a sublay repair working, in most cases, in the same space where the mesh is then placed, without entering the abdominal cavity. As already mentioned, the most diffused sublay endoscopic repair technique proposed in the last years is the eTEP [21]. As specified above, due to its wide diffusion and the relatively large number of published articles, this approach was excluded from our review, and we focused the attention on all the other approaches proposed to perform a retromuscular repair by posterior access. In fact, the systematic review and metanalysis published in 2022 including 13 studies, concluded that eTEP is a promising and safe procedure [21] and several more studies have been published during the last years.

Nevertheless, we cannot discuss about the posterior approaches without comparing them to the eTEP, that today can be considered the main reference for this group. This technique was first published in 2012, based on Daes’ experience in the inguinal hernia and involves direct access to the retromuscular space without entering the abdominal cavity [27]. In the systematic review and metanalysis by Aliseda et al., this approach presented good results in terms of surgical site infection (0%), seroma (5%), major complications (1%), intraoperative complications (2%), conversion rate (1%), mean hospital length of stay (1.77 days) and recurrence rate (1%) [21]. In our study 11 techniques were included in this group, in which bleeding has been the most reported complication, maybe related to the dissection in the retromuscular space. Seroma and SSI were not significantly reported, with seroma rates ranging from 0.8 to 7.1%, that is comparable to the rates reported for the eTEP. Recurrence rates ranged from 0 to 2.7%, but follow-up is reported only from 6 months to a maximum of 18 months. The mean hospital stay ranged from 1.8 to 4.3 days, superior to the value reported for the eTEP. The authors emphasize how some complications like injury to the linea alba, retromuscular hematoma or injury to the neurovascular bundles could, theoretically, increase morbidity and reoperation rates especially at the beginning of the learning curve. So, they conclude that this procedure needs to be performed in the hands of well-trained hernia surgeons [21].

In this group there are also two techniques that use staplers for the section-suture of the fascia [28, 29]. These are mainly extraperitoneal, but the peritoneal cavity is always evaluated for the possible risk of visceral injuries during the use of the stapler, especially in the case of visceral adhesions. Both were indicated for the treatment of ventral hernias and DR, with good results in terms of technical difficulty (operative time 82.4–90 min), complications (seroma rate 0.9%, wound complications rate 3.6% for THT) and recurrence rate (0-2.7%). The promising good results of this approach face with some problems that regard the tightness of the posterior plane during the THT technique, due to the tension caused by the medial plication that occurs during the mechanic section-suture, especially in the case of large defects. The Trentino Hernia Team compensates for this with a release of the posterior sheath of the rectus medial to the neurovascular bundles to reduce tension on the posterior fascia, or by performing a partial TAR. This measure eliminates tension on the rear surface, lowering sealing problems [30]. However, the size of the defects currently presented in the literature does not indicate these techniques for large secondary defects. In fact, the two studies included in this review reported a mean inter-recti distance of 47–49 mm and a mean hernia width of only 16 mm (Table 2).

The other posterior techniques presented a mini or less open access in 2 approaches [15, 31, 32], a single incision access in one case [33] and laparoendoscopic approach in 5 cases [34‐38]. They were all comparable in terms of operation time (97.5–285 min) and they were indicated for small hernias (width 22–50 mm). Only in the e-Rives the IRD was reported (40–60 mm) [38]. The MILOS study presented the largest cohort of patients of all the studies included in this systematic review, with 615 patients and a follow-up of 12 months, the authors reported 1.6% of recurrence rate [36]. Recurrences were registered only in the studies by Manetti et al. [28] and Reinpold et al. [36], 2.7% and 1.6%, respectively. All the other studies did not registered recurrences, but this is obviously related to the short follow-up (9.2–18 months) and to the small cohort of patients included in the studies. As regards the complications, seromas ranged from 0.8 to 7.1%, and wound complications were reported only in two studies (3.6% and 4%) [15, 37]. Bleeding was registered in 4 studies, maybe due to the dissection in the retromuscular space [28, 29, 32, 36].

In summary, all the posterior extraperitoneal approaches present a specific feature: there is one main working space (retromuscular) with a low risk of seroma because there is no preaponeurotic detachment and low risk of intra-abdominal injury due to the almost totally extraperitoneal nature of the approach. They give optimal functional results with no drain needed usually. However, on the other hand, they may present, depending on the type and size of the defect as well as the morphology of the patient, little vertical bulging at the skin level, reported and described sometimes as temporary, or the presence of a residual hernial sac included in the repair suture as a possible site of persistent seroma [39]. Furthermore, the learning curve is quite long [40]. In our review, among the 11 studies presenting a posterior extraperitoneal approach, one placed the mesh preperitoneal [35] and 10 in the retromuscular space and they were mainly indicated for the repair of ventral hernias. The learning curve was never investigated and there is no report about the morphological outcomes.

According to the access site, 16 techniques used the anterior approach with subcutaneous space as the main work camera. Most of them were just analyzed and discussed in a previous review focused on endoscopic subcutaneous onlay repair, in which the authors underline the similarities among the different names proposed for the same surgical technique and propose to unify them under one term, Endoscopic Onlay Repair (ENDOR) [8]. Since the article published by Bellido-Luque in 2015 [11], the preaponeurotic plane has been increasingly considered as a space of possible use for the treatment of midline defects. After the publication of Bellido-Luque, other authors published the same approach almost simultaneously [41, 42]. Most of the techniques belonging to this group involve the placement of an onlay mesh (Table 3), and they registered low complication rates as well as good results from a functional point of view (wound complications 0.8–6.4%, other surgical complications reported: SSI in 6 studies, bleeding in 2 studies). However, they are mainly used for the repair of DR with small umbilical hernias. The inter-recti distance reported in the studies included in this review ranged between 32 and 60 mm and the mean hernia width between 15 and 80 mm. In two anterior approaches the mesh is not placed onlay. In the first, the bilayer technique by Philippe Ngo [17], there is no mention of mesh. The use of mesh in abdominal wall repair has become a standard practice in modern surgical procedures because it significantly reduces the risk of recurrence allowing for a tension-free repair and leading to better outcomes and reduced postoperative pain for patients. Therefore, no-mesh repair should not be considered nowadays, especially in the case of complex abdominal wall defects like midline hernias and DR with IRD greater than 50 mm. The second is the TESAR technique, published by our group in 2019 for the repair of ventral and incisional hernias [43] and in 2021 for DR and umbilical hernias [44]. This approach is the only technique to date that provides anterior access with retromuscular mesh repair. We believe that this procedure has some advantages and that it is indicated not only for the repair of defects such as DR and umbilical hernias, like most anterior approach techniques, but that it can be considered among the possible options of choice in patients with secondary defects at high risk of intraperitoneal adhesions. On the other hand, the onlay repair carries some other controversial aspects, like the presumed increased risk of complications. As reported in the present study, among these approaches the risk of seroma ranged from 4.7 to 81% and there was also an increased risk of SSI reported in the different experiences. Moreover, there is an increased risk of recurrence, compared to the sublay repair (Table 4). The studies included in this review reported a recurrence rate of 1.9–12.5%, and 6 studies reported no recurrences, but with limited follow-up (1–24 months). In fact, the retromuscular space is often considered as the best positioning plane for a mesh in the literature, considering it safer in terms of surgical site infections (SSI) and recurrence [45, 46]. Nevertheless, the main advantage of the anterior approaches is the safety, with a very low risk of visceral injury, and no need to work against abdominal pressure and with the instruments in reverse, like in the posterior approaches. It is also possible to remove all the hernia sac, giving an optimal morphological outcome, especially in thin patients.

Overall, the studies included in this review, are from Europe in 14 cases, followed by Asia (9 studies) and America (6 studies), showing a worldwide tendency to develop new approaches for the repair of abdominal wall defects. The real limitation of these studies is the poor population, in most cases the number of patients included does not overcome 50 cases, in fact after excluding the only 4 studies with more than 100 patients, the mean number of patients included was about 30, and in one study the number of patients included was only 8. Only the study of Reinpold et al. included a large number of patients (n = 615) [36]. Most of them are case series or retrospective studies with poor follow-up that, when reported, ranges from 1 to 24 months. So, the results should be taken with caution, especially those about the recurrence rates, that in most cases are reported as null.

Posterior approaches are quite similar to the eTEP, which can be considered as the main reference in this field. Anterior approaches with onlay mesh are in most cases the same technique called in differently, as already highlighted in a previous article [8]. TESAR is, to date, the only anterior approach performing a sublay repair [43, 44].

As reported in Table 5, the posterior approaches were investigated in a relatively larger group of patients (998 vs. 695, posterior vs. anterior, respectively), but they were used to repair smaller hernias (16–50 mm vs. 15–80 mm, posterior vs. anterior, respectively). Operative times were longer for the posterior approaches (82.4–285 min) in comparison to the anterior techniques (60–195 min), and this can be related to the possible higher difficulty in performing these approaches that may present a steep learning curve. Seroma rate was higher in the anterior approaches (4.7 − 81% vs. 0.8 − 7.1%, anterior vs. posterior, respectively) and this is linked to the wide subcutaneous dissection performed with these techniques. On the other hand, the posterior approaches presented a higher possibility of bleeding, maybe due to the dissection in the retromuscular space.

The limitations of this review are related to the different populations of patients included in the selected studies, the heterogeneity of the studies with different inclusion criteria, poor follow-up, and scarce outcome data.