Prevention of incisional hernia after kidney transplantation: study protocol for a randomized controlled trial

Incisional hernia is a common complication after kidney transplantation with an incidence of 1.6–18.0% [1‐4]. Several studies have identified multiple risk factors for the development of post-transplant incisional hernia that can be grouped into patient and donor factors, factors related to immunosuppression and factors related to the location and type of surgical incision [1‐7]. Incisional hernia in transplantation is a poorly recognized pathology that is a source of morbidity and aesthetic concern for the transplanted patient. International guidelines on abdominal wall pathology recommend, in view of the limited scientific evidence, the performance of well-designed clinical studies to answer the usefulness and safety of the use of mesh reinforcement in abdominal closure in situations considered high-risk and lateral incisions, both characteristics of the surgical approach to transplantation [1, 17, 18].

Regarding patient-related factors, age > 50 years, female sex, obesity and cadaveric donor transplantation have been identified as potential risk factors. In view of the above, the renal transplant patient should have a higher risk of incisional hernia due to prolonged time on dialysis, immunosuppression and a high prevalence of comorbidities such as obesity, DM, chronic obstructive pulmonary disease (COPD) and hypertension [1, 2, 4]. In contrast, the incidence of incisional hernia in this population reported in the literature is lower than that reported for median laparotomy so the development of incisional hernia would appear to be related to factors specific to the surgical incision including, location, closure technique, tissue characteristics at the incision site and local biomechanical forces [4, 19].

Regarding factors specifically related to the surgical wound, the type of incision and surgical wound infection have been identified as risk factors [13, 19]. Different approaches to renal transplantation have been described including paramedial, oblique, extended groin, pararectal and field hockey stick incisions [1, 2, 4, 19]. Systematic reviews in the context of general surgery have shown that paramedian and transverse incisions have a lower incidence of incisional hernia [10, 11, 15, 20, 21]. The 2 most commonly used approaches are the oblique hockey stick approach from 2 cm above the anterior superior iliac spine to the pubis, involving the greater and lesser oblique and transverse muscles, and the external pararectal incision from 3 cm above the umbilicus to the pubis, involving the aponeurosis instead of the muscle. Paramedian incisions are similar to field hockey sticks and pararectal incisions in that they all use the lunate ligament at the lateral border of the rectus abdominis muscle to gain access to the retroperitoneal space in the iliac fossa. In contrast, oblique and extended inguinal incisions are also similar and extend laterally parallel to the muscle fibres of the external oblique. Studies comparing the incidence of incisional hernia between the field hockey stick incision and oblique incisions show, in principle, a lower incidence in the latter [2, 4, 19]. In fact, European surgical guidelines recommend transverse incisions not only because of a reduced incidence of incisional hernia but also because of a lower analgesic requirement [10, 15, 20]. Nanni et al. compared both types of incisions showing a reduction in the incidence of incisional hernia by abandoning the hockey stick incision and the extensive muscle section [19].

Regarding the surgical wound closure technique, there are no specific studies in the context of renal transplantation and we can only extend the recommendations established by the international guidelines for mid-laparotomy closure, which recommend the use of monofilament partially absorbable suture, with a gauge of 2/0 and mounted on a small size needle (26 mm) to perform a continuous monofilament suture taking an amount of tissue between 5 and 8 mm on each side and with stitches 5 mm apart (“small bites”) and keeping a ratio between the length of the suture and the length of the wound of at least 4/1 (4 cm of thread for each cm of wound) [20, 21]. There is no reference in the studies included in the systematic review to the use of the “small bites” technique or the use of prophylactic meshes that have been recommended in high-risk closures without a clear definition of the risk factors considered. On the other hand, in the context of transplantation, the potential risk of infection in the immunosuppressed patient should be taken into account when considering the use of mesh in surgical wound closure [2, 4, 9, 13].

Surgical infection is considered the main risk factor for incisional hernia formation. Bacterial proliferation induces an immune response that disrupts normal collagen synthesis and surgical wound healing. Organ dysfunction in the context of transplantation and immunosuppression are risk factors for surgical infection and thus for incisional hernia. Therefore, prophylaxis and aggressive treatment of surgical wound infection is a priority and will secondarily impact the risk of incisional hernia [2, 4, 13].

The relationship between obesity and incisional hernia may be determined by increased intra-abdominal pressure which increases mechanical stress on the incision, but obese patients also have an increased risk of surgical wound infection which may explain the increased incidence of incisional hernia [1, 2, 4, 7, 8].

Immunosuppressive regimen may be an important modifiable risk factor for the development of incisional hernia. Although several agents have been associated with an increased incidence of incisional hernia, specifically mycophenolate for its antiproliferative effect and sirolimus (m-TOR inhibitor), further studies are needed to definitively establish which immunosuppressive regimen is considered most appropriate [1, 2, 4, 8].

Muysoms et al. in 2017 conducted the review of all published articles on the use of prophylactic mesh reinforcement (excluding studies on para-stomal hernia prevention) with no restrictions on the type of study or qualitative analysis [20]. All data on the degree of contamination and number of wound and/or mesh infections were extracted and analysed. The use of prophylactic mesh reinforcement to prevent incisional hernias had been published in the literature in 1,759 patients, with an overall wound infection rate of 12% and a mesh infection rate of 0.6%. The procedure, it was concluded, could be considered safe and effective in both clean and clean-contaminated surgery. Regarding the position of the prophylactic mesh, both supraaponeurotic and retromuscular positions have been used. Both seem equally safe and effective and probably the position of the mesh will depend on the preference of each surgeon. However, to identify in which group of at-risk patient’s prophylactic mesh should be recommended, the authors conclude that further studies are needed. In contrast, the existing literature on the prophylactic use of mesh for wall closure in the context of renal transplantation is very scarce [22‐25]. Of the 3 articles identified, 2 of them refer to their use for the prevention or treatment of compartment syndrome in renal transplantation [22, 23]. Beasley et al. use a propylene mesh as a bridge between the posterior fascial planes with the aim of achieving enlargement of the closure and reduction of the pressure exerted on the graft; in this way, the graft was saved in 15 of the 17 cases used, the associated complications being minor in all cases with the occurrence of 5 cases of seroma and 1 lymphocele. In 2015, Wood et al. publish the use of prophylactic polypropylene mesh in the prophylaxis of compartment syndrome in renal transplantation. Of a total of 134 patients in whom mesh was implanted only 1.5% developed surgical wound infection, a result similar to that of the non-implanted population (1.3%). The mesh removal rate was 6% (8/134). Only the article by Michalski et al. referred to the use of mesh for prophylaxis of early surgical wound complications [22]. A reduction, although not significant, of surgical wound complications was identified in the group in which closure reinforced with Vycril™ (polyglactin 910) resorbable mesh was used. No association was identified between the use of prophylactic mesh and the occurrence of surgical wound infections, a potential complication feared by the use of mesh in the context of immunosuppression and transplantation.