4.1 Feasibility, safety, and effectiveness of ESR
Currently, this is the first comprehensive report of ESR from China; 153 of 156 included patients who had a planned ESR were operated on successfully, suggesting that this procedure is feasible for experienced hernia surgeons. Even if the ESR fails, there are still some fallbacks, such as Lap-TAPE, Lap-IPOM, and even open surgery. Although the operative time of ESR was much longer than Lap-IPOM because the dissection of a large sublay space under endoscopy was time-consuming, acceptable results in terms of intraoperative injury and postoperative recovery, as well as postoperative complications, were obtained. The median postoperative hospital stay of this series was three days, maybe a little longer than that of Lap-IPOM. The major cause is that drainage was placed in 58.2% of cases and most drainage was removed before discharge.
One crucial concern in the TES procedure is whether the separation of the hernia sac will damage the adherent bowel inside the sac. Our preventive measure was to open the sac around the hernia ring when it was difficult to separate, which allowed us to clearly see the intraperitoneal adhesion. Consequently, only one serosal injury of the small bowel occurred in this study.
In ESR, a large-size mesh is used with less fixation or even with no fixation when compared with that in Lap-IPOM. In Lap-IPOM, the defect is usually closed directly. During ESR, TAR is often needed for a large-to-medium midline defect, and it helps reduce the tension. Less fixation, defect closure with low tension, and no large incision as with the open sublay repair, these all contributed to mild postoperative pain. In TES procedure, the whole procedure and the mesh were totally in the extraperitoneal space, causing little interference with the abdominal cavity. Therefore, most patients resumed eating quickly.
The most serious postoperative complication observed was bleeding in the extraperitoneal space in two patients, both of whom had undergone TES repair. As the separated sublay space is large, it is difficult to control the bleeding once incomplete intraoperative hemostasis or postoperative bleeding occurs. This is a new complication that deserves our attention, and complete hemostasis should be achieved during surgery.
Up to the end of data collection, no mesh infection, delayed intestinal fistulas, or adhesive ileus was observed. However, one umbilical hernia with diastasis recti recurred 5 months after TAS surgery because of insufficient mesh coverage.
4.2 The critical surgical skills
The first critical skill is the “partition breaking” technique. In ESR, we need to separate a large retromuscular space; however, the most commonly used sublay plane in the medial region, the retro-rectus space, is not connected with the lateral retromuscular space and the retro-rectus spaces of the other sides. Therefore, one or several anatomic partitions should be broken to satisfy the placement of a large mesh. The key points of the technique have been described in Section 2.
The second critical skill is TVS technique. For a large incisional hernia, it is worth breaking the partition. However, for a small ventral hernia, such as an umbilical hernia, cutting off the posterior sheath causes increased trauma and damages the integrity of the rectus sheath. It would be more appropriate to separate at another sublay plane, the plane between the posterior sheath and the peritoneum. This space not only directly connects with the lateral retromuscular space and then the retroperitoneum, but directly connects with the same space of other side. Equally important, along peritoneum, there is only some fascia structure. So, no aponeurosis or muscle needs to be cut off during separation. Anatomically, the peritoneum is just like an eggshell membrane wrapping all abdominal viscera and thus can be called as a visceral sac. The peritoneum from all sides (superior to inferior and anterior to posterior) connects and forms a whole visceral sac. The separation is implemented as if peeling an eggshell completely along its shell membrane. We named this technique of separating along the surface of the peritoneum, which potentially forms a whole visceral sac, as “total visceral sac separation (TVS)” technique (26). Certainly, only in few hernia repairs, it needs to separate a wide range of visceral sac. However, it is potential to separate the visceral sac as large as possible at any region of abdominal wall. The separation of the whole visceral sac is difficult, especially at the part behind the posterior sheath, because the peritoneum there is very thin. Therefore, TVS is a challenging procedure, and its successful implementation requires more patience and time. In this study, 19 patients with TES repair from three hospitals were successfully operated on combining with the TVS technique. In another three patients with midline defects, the TVS technique failed because of peritoneal damage, and it were converted to routine TES procedure which operated at the retro-rectus plane. Additionally, TVS is especially suitable for primary ventral hernia repair, such as umbilical hernia, linear alba hernia and lumbar hernia.
Third, the trocar layout and procedure design are crucial for the successful implementation of ESR. Our layout and procedure are slightly different from those reported in the literature. Belyansky's TES procedure(6) for midline defects usually employed a full-length crossover. We speculate that his procedure emphasized the separation of the entire retro-rectus space, facilitating the placement of a large mesh. Instead, we do not employ a full-length crossover. For example, for a small lower midline defect, if its margin is ≥5 cm away from the umbilicus, crossover is only implemented in the lower half of the abdomen, preserving the integrity of the posterior sheath above the umbilicus. Another probable cause for such difference is that the defect size in our study was much smaller than that in Belyansky's study (6) (17.9 cm2 [calculated as an ellipse] versus 132.1 cm2 [calculated as a rectangle], respectively). In the TAS procedure, our procedure for lower midline defects was similar to that of Prasad (17) and Masurkar (19). But for a large umbilical defect, Schroeder (18) and Masurkar (19) placed the trocars at the lateral region only on one side; the proximal posterior sheath and peritoneum together were then cut open. A whole peritoneal flap was prepared after the separation of the retro-rectus space of both sides. Instead, we preferred to raise two symmetrical flaps. Six trocars, three on each side, were placed at the lateral abdomen. The two flaps were raised by the instruments from the contralateral side and were sutured together on the midline after repair. This difference may be because robotic is used more frequently in TAS (20-24) than in TES (14-16); however, the use of robotic is not widespread in hernia surgery in China. Therefore, suturing two flaps together on the midline is much easier than suturing one flap at a close range in routine endoscopic surgery. Moreover, the unilateral trocar layout was insufficient for implementing TAR on two sides.
4.3 Terms
Different names, including retromuscular, retro-rectus, Rives–Stoppa, and preperitoneal space, have been used in the literature. These terms have nuanced differences resulting from the development history of Rives–Stoppa technology and the anatomical names of different abdominal wall regions (29). However, in most cases, these terms are interchangeable and can be replaced by one name, sublay. Therefore, the different reports of similar procedures of placing the mesh at the sublay plane under laparoscopy can all be regarded as “laparoscopic sublay repair.” Because the totally extraperitoneal approach does not enter the abdominal cavity, we consider the term endoscopic to be broader and more appropriate than laparoscopic. Therefore, we call such operations as “endoscopic sublay repair (ESR)” for ventral hernia (26).
In terms of surgical approaches, there are also different expressions: totally extraperitoneal, enhanced-view TEP, extended TEP, transperitoneal sublay, transabdominal retromuscular, TAPP, and extended TAPP. Overall, the approaches of ESR for ventral hernias are the same as those for laparoscopic inguinal hernia repair (LIHR) and can be categorized as “totally extraperitoneal” and “transabdominal.” Adding “sublay” after “totally extraperitoneal” and “transabdominal,” we call the two procedures “totally extraperitoneal sublay” and “transabdominal sublay” (Figure 7). Accordingly, we replace P/PP with S and abbreviate them as TES and TAS. Currently, the frequently used name for the extraperitoneal approach for ESR is enhanced-view TEP (6, 10). This name was originally given to the procedure for complex LIHR in which the highly positioned camera provides an enhanced view, facilitating the subsequent dissection. However, when it was introduced to ESR for ventral hernia, it did not match the reality because no enhanced view seemed to be obtained. Therefore, we proposed a more generalized term, TES. Together with TAS, we recommend these two terms because they summarize and categorize the many reported procedures with various names. As TES and TAS correspond with those of LIHR, they are easy to remember and aid in understanding the procedures.
4.4 Frequency of TES and TAS
In this study, about eight of nine cases were completed by TES. According to the experiences from LIHR, TAPP provides a larger working space, so the procedure is easier than TEP. However, the situation is different in ventral hernia. ESR requires a much larger separated sublay working space than LIHR does. In the TES procedure, the gas filling in the space between the peritoneum and the muscle depresses the peritoneum and helps separate a large working space. The instruments and operations in TES are all in the extraperitoneal space; however, the position of the instruments and the operations in TAS is split, making space separation in TES more direct and easier than that in TAS. Because the operation of TAS is toward the “ceiling,” the preparation and suturing of the peritoneal flap are difficult without robotic’s assistance. Above all, Chinese surgeons generally prefer TES over TAS.
4.5 Limitations of the study
The follow-up was relatively short, and patients with no symptom were only followed up by telephone, so the recurrence rate may be underestimated. The patients were included from ten hospitals in different areas, so the indications, detailed procedure, and data evaluation were not definitely consistent. As a non-controlled retrospective study, we cannot conclude the differences of all variables between ESR and Lap-IPOM or open sublay repair. All of these deficiencies should be improved by standardized controlled studies in the future.
4.6 Indications, contraindications, and prospect of ESR
For TES, small-to-medium ventral hernias (defect width <6 cm) are the major indications. Without robotic’s assistance, the indication range for TAS is smaller than that for TES. TAS is suitable for small ventral hernias, especially for M5 and L3 defects. Contraindications include hernias with severe adhesion in the hernia sac, large-to-medium incisional hernias (defect width >6 cm), or small defects combined with “loss of domain.”
Objectively, ESR is still a difficult operation. However, for small-to-medium ventral hernias, some disadvantages of Lap-IPOM and open sublay repair can be avoided if ESR is successfully implemented. With the generalization of ESR and the increase of experience, we believe that the indications for ESR will gradually extend. ESR, Lap-IPOM, and open sublay repair, together, will dominate the surgical treatment of ventral hernias for a long time in the future.