In many studies, TEP repair is reported as a safe and effective procedure for treating inguinal hernias, and the advantages over open repair are less pain, better cosmetic outcomes and shorter recovery [7-9]. However, many institutions hesitate to introduce TEP repair because of the limited working space and the peculiarity of the anatomical landmarks [1, 10]. Compared to TEP repair, TAPP repair has the advantage of a clear field of view inside the pelvic cavity similar to other laparoscopic surgeries. However, TAPP repair is associated with higher rates of port-site hernias and visceral injuries [11] and others report that TAPP repair has the possibility causing more adhesions, leading to intestinal obstruction[12].
PI is an intraoperative complication specific to TEP repair which occurs during the dissection of the preperitoneal space. Several studies have reported that the incidence of PI ranges from 10% to 65%, and the rate increases in recurrent and bilateral hernias [9, 13-16]. Pneumoperitoneum caused by PI induces loss of the working space inside the preperitoneal space, leading to prolongation of operative time and difficulty in performing the operation safely. In cases with small PIs, closure of the defect is preferred [13], however, it is difficult to control large PIs and conversion to anterior approach or TAPP repair may be needed in severe cases [9, 11, 15]. In the present study, the total PI rate was 31%, and the conversion rate was 5.6% which was a major cause of prolonging the operative time.
To clarify the factors causing PIs, we focused on the size of hernia and analyzed the PI cases in large hernias by breaking down the TEP procedure into five phases. By this way, we clarified that the PI was likely to occur during the dissection of the medial side of the hernia sac by a sharp dissection using an USAD. Based on these findings, we made two presumptions causing PI during the dissection of the hernia sac as followed. 1) Maneuver during the hernia sac dissection. 2) Possibility of thermal injury due to the narrow working space. The medial side of the hernia sac is relatively adherent to the underlying structures such as the vas deferens. Therefore, dissecting the adherent membrane of the hernia sac, especially a sharp dissection utilizing an USAD may be one factor causing PIs. For presumption 2), we presumed that the large hernia sac itself caused the narrowing of the working space, leading to an increase of injury. Additionally, when the hernia sac is large, the peritoneum is originally thin and weak, causing more opportunity of injury. We also considered the possibility of thermal injury to the peritoneum since the active blade of the USAD is long (15–20 mm), and the effect of lateral thermal spread to the surrounding tissue is wide (2–5 mm) enough to injure the peritoneum in a narrow and limited space [17, 18]. Our future direction is to initiate a new method to quantify the working space inside the preperitoneal space and to determine whether the hernia size and other factors affects the working space.
Based on the presumptions causing PI, we next considered the prevention method for PI during the hernia sac dissection and the remaining preperitoneal space dissection. When utilizing an USAD in medium power settings (60-70% power), the mean temperature of the active blade elevates around 80℃ with an application time of 5 seconds, and reaches to a plateau around 80-100℃ when applied for a longer period of time. However, the mean temperature can easily elevate over 100℃ even with an application time of 5 seconds and over in maxium power settings (100%) [17, 18]. Since protein coagulation and denaturation begins over 60℃ and collagen denaturation and cell membrane permeabilization begins over 80℃ [19], we believe that minimizing the application time (within 5 seconds) as suggested by Pogerlic et al. [20], and minimizing the output power (60-70% power) should be useful to prevent maxium heating of the active blade. Moreover, in order to prevent thermal injury and cavitation damage to the surrounding tissue, maintaining a safety margin with a proper traction should always be considered. Furthermore, the hernia sac dissection should be carried out properly by a combination of a blunt and sharp dissection while performing a delicate hemostatic procedure. Under these methods, we believe that the peritoneum injury will be minimized, leading to the safety of the intra-abdominal organs, which is a significant advantage of TEP repairs compared to TAPP repairs.
As shown in our study, recovery methods for the PI was effective regardless of the size of the defect. To control the narrow working space created by PI, recovery methods should be strongly considered. Several studies have reported repairments of the peritoneum utilizing endoscopic metal / non-metal stapling, endoscopic suturing and pre-tied suture loop ligation [13, 14]. We considered that the PI defect should be repaired because of the two points as followed. 1) Narrowing of the working space due to pneumoperitoneum causes decrease of maneuverability, resulting in prolongation of operative time. 2) Can be causes of postoperative internal hernia and adhesive intestinal obstruction [12]. Moreover, when the peritoneal defect is large, conversion to TAPP may cause 1) Prolongation of operative time. 2) Effect the cosmetic outcomes by adding another skin incision. 3) Possibility of adhesive intestinal obstruction. Therefore, as long as the working space is maintained, we recommend repairment of the peritoneum by continuous suturing. In cases which the working space is difficult to maintain, a continuous suture while deaerating the peritoneal cavity may be effective.
Several studies have reported that the PI rate is lower in an expert surgeon compared to trainees [15, 21]. In the present study, PIs mostly occurred during the dissection of the medial side of the hernia sac, which a forced dissection of the adherent membrane is needed. Not only a sharp dissection utilizing an USAD, but also a forceful dissection with an unbalanced traction and countertraction may easily injure the peritoneum. We considered that the understanding of the characteristics among each energy device and the maneuver based on a proper traction was the difference between our institution and expert surgeons.
This study has some limitations including its retrospective design with small number of cases and lack of the long-term follow-up. The long-term follow-up was limited to complication cases occurring within 30 days of the procedure. Additionally, we are a developing institution in terms of TEP repair, which the learning curve may be unstable during the study.