Incisional Hernias Post Liver Transplantation: Current Evidence of Epidemiology, Risk Factors and Laparoscopic Versus Open Repair. A Review of the Literature

Results

Epidemiology - risk factors. The lifetime risk for incisional hernia formation in liver transplant recipients ranges from 1.7% (6) to 43% (7), even though lower rates have been reported (6, 8-10).

In 2002, a group of German investigators studied 290 liver transplant patients for 10 years and reported a 17% rate of incisional hernia formation (11). The same group concluded that acute rejection (with steroid treatment), post-surgery thrombocytopenia and Mercedes type incision were risk factors.

The type of abdominal incision is an important risk factor contributing to the development of incisional hernia. A large study including almost 1000 patients, with an exclusive use of a Mercedes incision, reported an incisional hernia rate below 5% (12). In the study published by Gastaca et al., with more than 600 patients having been operated with a bilateral subcostal incision, the incisional hernia rate was reported to be 1.7%, much lower than the rate associated with the Mercedes incision (6). Another study published by Montalti et al., has reported an incisional hernia rate of 32.4%, and mTOR inhibitor rapamycin (Sirolimus), male sex, high BMI, and MELD score >22 were identified as risk factors (9). Kahn et al. has also reported on a high hernia rate exceeding 23%, and considered Sirolimus (prescribed in almost 20% of transplanted patients suffering of hernias), along with end stage cirrhosis as major risk factors (13).

Risk factors for incisional hernias following LT are numerous. In detail, male sex, abdominal re-interventions, living-donor liver transplantation, postoperative respiratory complications, immunosuppressive therapy with the use of steroids, prolonged stay in intensive care unit, acute rejection, severe post-transplantation ascites, viral hepatitis, obesity (BMI >25 kg/m²) (8), re-transplantation, and bilateral subcostal incision with midline extension (6), have been recognized as predisposing risk factors. Apart from the aforementioned parameters, the study published by de Goede et al., has demonstrated that advanced recipient's age (>60 years) is an additional risk factor for the development of post-transplantation hernia (7).

According to Smith et al. (10), obesity is an independent risk factor for hernias. The mechanism underlying this phenomenon includes an increased intraabdominal pressure, setting the incision under mechanical stress. Moreover, obese patients are more prone to surgical site infections, a fact which favors incisional hernia development. In univariate analysis, obesity was among the most important risk factors for hernia development, while in multivariate analysis, obesity remained an important risk factor only for patients subjected to LT (10).

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Figure 2.

Prisma flow diagram for study identification and selection.

Immunosuppressive therapy seems to be an important and modifiable risk factor for the development of incisional hernia, with several studies yielding a wide variety of outcomes. The negative impact of steroids on the wound healing process has been well documented, not only in LT patients, but in all types of incisions (6, 14). Apart from steroids, MMF (mycophenolate mofetil) administration has been documented to be an additional risk factor for hernia formation (15). Finally, immunosuppressive therapy with the use of mTOR inhibitors, such as Sirolimus, has been associated with higher rates of incisional hernia development (9, 13, 16).

Laparoscopic vs. open repair. Traditionally, surgical repair of incisional hernias, especially the large ones, was performed in an open fashion, either with mesh implementation in an inlay or onlay fashion, or with primary closure (Figure 3A, B, C and D). Several studies reviewing post-transplantation open incisional hernia repair have claimed that mesh implementation diminishes the risk of hernia recurrence, without amplifying the risk of infection. The same results have also been observed regarding other abdominal transplant recipients (11, 12).

Nowadays, the extensive use of laparoscopic techniques has dramatically altered the surgical repair options of these patients. Even large ventral and incisional hernias in non-transplant patients are more frequently repaired laparoscopically than in the past. Laparoscopic repair of ventral hernias has demonstrated fewer recurrences as well as infections, compared with an open repair (17), and has become the procedure of choice in experienced centers. Despite the prolonged operative time, in experienced hands, laparoscopic repair has been proven to be a safe and feasible alternative for post-transplantation hernia patients, demonstrating an outcome superior to its open counterpart, in terms of shorter length of hospital stay (LOS), and lower recurrence and complication rates. Recurrence rates for transplanted patients range from 3-10%, while infection rates lie between 1 and 3% (17, 18). Surprisingly, though, a meta-analysis of 8 studies comparing open vs. laparoscopic repair, concluded that short-term complications were half as likely to occur (14% vs. 27%) after a laparoscopic repair (19).

From another aspect, large incisions together with the administered immunosuppressive therapy in transplanted patients, often result in the development of large and/or multiple incisional hernias. The study by Raftopoulos et al. has reported on 72 patients suffering from large ventral or incisional hernias with an average hernia surface area of 125 cm² and examined the outcomes of hernia repair. Major complication rate as well as hernia recurrence rate were significantly reduced in the laparoscopic repair arm of the study (20).

Mekeel et al. have analyzed the outcomes of 27 patients who underwent incisional hernia repair following LT. Patients treated laparoscopically (n=13), demonstrated a low risk of mesh contamination and hernia recurrence, however, no significant difference was observed between the open and laparoscopic repair group. It should be noted, however, that the open repair patients had undergone more abdominal operations before transplantation than their laparoscopic counterparts, which may explain the increased risk of hernia recurrence in open repair patients, due to the presence of weaker abdominal fascia. Despite this fact, the postoperative LOS in the laparoscopic group was significantly longer, compared with the open repair (17).

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Figure 3.

Intraoperative findings during open hernia repair. A: Hernia sac; B: Hernia content; C, D: Hernia repair using intraperitoneal mesh.

Nowadays, several studies have shed more light on the optimal type of surgical repair for incisional hernias, apart from post-transplantation incisions. Al Chalabi et al. have completed a meta-analysis of randomized controlled trials regarding the management of incisional hernia, and concluded that laparoscopic repair is safe and reliable, requiring a longer intra-operative time compared to open repair, without any statistically significant difference between them. The LOS between the two arms of the study was equal, as was also the recurrence rate, with a post-operative infection rate being higher in the open hernia repair group (21). In the same way, larger prospective controlled trials are required to clarify exactly the role and potential benefits of laparoscopic surgery, over an open repair, in the management of post-transplantation incisional hernias.

Technical difficulties, special considerations. Surgeons handling this patient group are confronted with some specific challenges. Technical difficulties arise mainly due to the large extent of incision, the different types of incisions, especially near the xiphoid process and costal margin, the large hernia surface and the multiple re-operations. Due to the variability in hernia cases, surgeons must be experienced in performing various types of surgical repair, with or without implementation of a mesh. Polypropylene mesh may be the first choice of surgical treatment of post-transplantation patients (22), but biological prosthesis is another useful and safe option in abdominal wall repair surgery in these patients (23).

Undoubtedly, dense intraabdominal adhesions are found in most cases. Prolonged or impaired healing, due to the immunosuppressive therapy, are expected to cause considerable morbidity (18). Surgeons must be familiar with the variety of combinations of the administered immunosuppressive agents and to consider their temporary adjustment or even discontinuation perioperatively. Moreover, liver transplantation itself, as well as its impact on body homeostasis, may strongly affect the postoperative LOS and hospital care. Treatment of a perioperative graft dysfunction or an abnormality discovered from an intraoperative biopsy of the liver graft may also be encountered (18, 24). Finally, vulnerability of immunosuppressed patients to various infections, not exclusively related to the prosthetic mesh, may complicate and prolong the postoperative course.