About 5%-11% of all abdominal surgery results in incisional hernia. This rate can be even higher among high-risk populations such as transplant patients. Lifetime incidence of incisional hernia following liver transplant is as high as 43% in recent studies. The transplant population is at higher risk for incisional hernia precisely because of their immunosuppressive therapy. Thus, it is imperative to understand the risk factors for incisional hernia in this unique patient population. This article focuses on understanding preoperative, intraoperative, and postoperative risk factors for failure of hernia repair in the transplant population in addition to discussing risk stratification for incisional hernia in this population. Furthermore, we discuss the utility of panniculectomy in abdominal organ transplantation. Additionally, we discuss the value of mesh placement in abdominal wall closure. Finally, we review the concept of vascularized composite allograft as a method for achieving abdominal wall closure for patients who have failed more traditional repairs and who are left with inadequate tissue for successful repair.
Approximately 5%-11% of all abdominal surgery incisions result in incisional hernia, but this rate can exceed 30% in complex wounds among high-risk patients such as those undergoing solid organ transplants[
Transplant patients are at especially high risk for hernia due to their immunosuppressed state and comorbid conditions which can hinder adequate healing and even hasten wound breakdown[
When planning elective surgery such as incisional hernia repair, careful consideration must be given to each patient’s immunosuppressive regimen. A multidisciplinary approach is highly recommended for care for the transplant patient, including transplant pharmacologists to assist with drug modulation in the perioperative period. Decisions regarding adjustments to immunosuppressive therapy should be made on an individual and real-time basis and with the expertise of the involved team. Unfortunately, there are currently no data available from randomized, double-blind controlled clinical trials on how to guide immunosuppressive therapy in the perioperative setting for this patient population, making evidence-based recommendations difficult. Furthermore, chronic immunosuppression remains a cofactor for recurrence and subsequent hernia repairs, thus adding to the complexity of hernia repair in this population.
Preoperative patient factors that predispose to incisional hernia in transplant patients include male gender, advanced age (studies cite ages greater than 45-60 as risk factors), elevated BMI (BMI > 25), smoking, malnutrition (serum albumin levels less than 3.5 g/L), connective tissue disorders (e.g., osteogenesis imperfecta, certain subtypes of Ehlers-Danlos syndrome, and Marfan syndrome), immediately preoperative chemotherapy and/or radiation to the operative site or region, presence of large volume ascites, COPD, previous surgery in the operative area, anemia, steroid use, diabetes mellitus, and immunosuppression[
Postoperative factors associated with incisional hernia include wound infection, pulmonary complications, prolonged ICU stay, severe ascites, anemia, thrombocytopenia, acute rejection with steroid treatment, and same-site repeat surgery with fascial reopening and reclosure[
Common to these risk factors - obesity, ascites, and COPD - is increased intra-abdominal pressure, which puts mechanical stress on the fascial closure and weakens the abdominal wall, making patients more prone to wound necrosis, breakdown, and hernia[
Technique-related factors that increase risk for an incisional hernia after transplant include excess tension upon fascial closure, emergency surgery, and type of incision[
Examples of incisions used in liver transplant recipients
Common incisions described for kidney transplant recipients include paramedian, midline, and low oblique muscle-cutting incisions, such as the Rutherford - Morison incision
Examples of incisions used in kidney transplant recipients. Please note that some incisions may be right- or left-sided, depending on patient anatomy and involved organ(s)
Finally, focused intraoperative assessment of fascia is essential. Although there may be concern for excessive fascial tension or even difficulty/inability to close the abdomen if there is not enough fascia, poor quality fascia must be debrided prior to closure. Including ischemic, nonviable fascia in a closure will greatly increase risk for wound breakdown, dehiscence, and exposure of the graft to infection.
Understanding how to avoid hernia complications in transplant patients is perhaps more valuable than understanding how to repair these hernias. Important measures to avoid hernia include active incision management (e.g., careful tissue handling, closing the operative area in multiple layers, placement of drains, and use of negative pressure incision management), as well as early identification of wound complications. Should wound complications occur, early management with operative debridement and washout as well as the use of adjunct modalities such as negative-pressure therapy with antibiotic solution irrigation may prove useful. However, hernias still occur in this complex patient population despite meticulous technique and early management of complications. Accordingly, risk stratification is helpful.
There is an established grading system created by the Ventral Hernia Working Group (VHWG) to predict surgical site occurances in patients undergoing ventral hernia repair based on patient risk factors and comorbidities. This was initially described in 2002 and consisted of four grades (low risk, comorbid, potentially contaminated, and infected). The grading system was then redefined in 2012, which resulted in Grades 3 and 4 being combined
Hernia Grading System as described by the Ventral Hernia Working Group[
Hernia Grading System | ||
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Grade 1 (low risk) | Grade 2 (comorbid) | Grade 3 (contaminated) |
·No history of wound complications
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·Comorbid conditions (DM, smoking, immunocompromised, COPD, obesity)
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·Presence of nearby stoma
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In addition to the grading system developed by VHWG, multiple other tools are used for risk stratification of complications developed after ventral hernia repair. Such models include the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP), European Hernia Society (EHS), The HERNIAscore, and Ventral Hernia Risk Score (VHRS). The HERNIAscore developed by Goodenough
VHRS is an additional tool available for risk assessment of surgical site infection (SSI). Based on VHRS, risk factors for SSI include concomitant hernia repair, raising of skin flaps, wound Class 4 (i.e., dirty), BMI greater than 40, and ASA Class 3 or greater[
Surgical closure of an abdomen following solid organ transplant is a critical aspect of the transplant, as a failure of closure greatly increases the risk for graft failure and infection. Primary closure of the abdominal wall is, of course, ideal, however cannot be achieved in approximately 20% of patients[
Significant tension on the abdominal wall from closure in patients with loss of domain can also lead to abdominal compartment syndrome, which in a newly transplanted graft can lead to graft failure. Foley catheters are commonly left in place postoperatively, often to monitor urine output, but also to monitor bladder pressures in the setting of possible abdominal compartment syndrome. It is imperative that the patient is intubated, paralyzed, and fully supine in order to obtain accurate bladder pressures. Increased abdominal pressure that does not cause compartment syndrome can still impede flow within the inferior vena cava and decrease portal venous flow to the liver. This is a known risk factor for graft failure following liver transplantation. Low flow states can also lead to poor venous return, resulting in decreased cardiac output and perfusion. Increased abdominal pressure after fascial closure can also lead to respiratory compromise, especially in patients with loss of domain. Thus, it is important to communicate with the anesthesia team intraoperatively to monitor peak pressures after closure, as some patients may require continued intubation in the immediate postoperative period. Elevated ventilatory pressure or changes in peak pressures may also serve as a real time indication of impending compartment syndrome so our group routinely solicits feedback from anesthesia throughout closure.
Obesity remains a significant risk factor for morbidity after abdominal surgery. Transplantation in general carries a higher degree of morbidity among obese patients. Large overhanging skin folds create a moist environment that increases the risk of postoperative infection. Furthermore, the large amount of subcutaneous tissue that must be traversed and potentially undermined in patients undergoing transplant has a higher risk of necrosis and infection. A large pannus may also create additional tension and stress on the incision, which may lead to separation of wound edges[
Ngaage
In the single-stage operation by Ngaage
The optimal type of mesh to use in hernia repair - and hernia prevention - is widely debated. However, there has recently been a greater shift towards the use of biologic mesh over synthetic mesh. Biological materials such as human acellular dermal matrix (HADM) and porcine acellular dermal matrix (PADM) have multiple advantages over their synthetic counterparts. Biologic mesh provides a scaffold that allows cellular and vascular ingrowth, thus benefitting from possible incorporation into native abdominal wall tissue[
Multiple studies have shown that mesh implantation during incisional hernia repair can decrease the risk of hernia recurrence without increasing risk for infection in the transplant population[
As mentioned, HADM has a greater tendency to stretch over time, given the higher relative content of elastin within the matrix when compared to Porcine versions. Some studies have documented increased rates of bulging and hernia recurrence in patients with large complex hernias repaired with HADM. Our group found that, unlike its human analog, PADM resists early stretching after implantation while still providing comparable tensile strength, thus demonstrating a clinically relevant but statistically non-significant benefit to using PADM in abdominal wall reconstruction in the transplant population[
Multiple operative techniques are currently used by general, plastic, and transplant surgeons to repair incisional hernias in transplant patients. Primary suture repair is often limited to primary ventral hernias with small defects less than 3 cm. However, some surgeons still opt for mesh reinforcement in small repairs due to higher rates of recurrence in this patient population. Repair with mesh is recommended for repair of incisional hernias larger than 2 cm in a non-infected field[
Open sublay (e.g., retro-rectus) mesh repair has been shown in some studies to have similar recurrence rates as compared to IPOM, but these sublayed repairs are notable for increased perioperative morbidity and hospital length of stay[
Sublay repair is often used in conjunction with component separation techniques in order to restore the linea alba and medialize the rectus muscles. Component separation in post-transplant patients is often challenging, as the native planes are often distorted and scarred down. Additionally, as mentioned above, incisions such as Mercedes incisions have both horizontal and vertical components, which can further complicate plane dissection and hernia repair. Black
While component separation is often a necessary maneuver to achieve fascial re-approximation, it is not without potential complications. Anterior component separation (ACS) requires creation of large subcutaneous flaps, which can disrupt the blood supply via transection of trans-rectus epigastric perforator to the overlying fat and skin, leading to skin necrosis and its downstream sequelae. As mentioned above, this dissection also creates large flaps, which often harbor enormous areas of dead space and associated fluid collections. It should be noted that perforator-preserving ACS techniques have been described with improved outcomes. A posterior component separation (PCS) allows for less subcutaneous dissection and also may be preferred in patients who have undergone prior ACS repairs. In cases where patients lack adequate retro-rectus space, a unilateral or bilateral transverse abdominis release (TAR) may be required to minimize tension while avoiding the neurovascular bundles at the lateral border of the rectus muscle. As a general rule, we recommend that the retro-rectus space be at least twice the size of the defect transversely in order to undergo repair without the need for TAR. An advantage of TAR is the ability to create a wide retro-muscular space that can extend to the psoas muscles, Cooper’s ligaments, and the central tendon of the diaphragm.
A meta-analysis from 2018 comparing open ACS to PCS with TAR showed similar hernia recurrence rates and wound complication rates; however, both larger and comparative studies still need to be performed[
Finally, robotic-assisted hernia repair can aid in abdominal wall reconstruction for complex and large-sized hernias. A robotic approach may facilitate dissection and component separation in the setting of dense adhesions and complicated post-transplant anatomy. It is our recommendation that such cases should be performed at hernia centers that specialize in both complex hernia repair as well as transplant surgery such that, if there are complications, the transplant team is readily available.
Significant variability exists between size criteria and the appropriateness of individual techniques among surgeons; therefore, surgeon experience, patient factors, and hernia morphology must be considered when choosing how to repair incisional hernia in solid organ transplant patients. Currently, there are no definitive algorithms for hernia repair in this population for multiple reasons. First, a reparative approach can be determined by size of fascial defect, patient risk factors, or even hernia stages. There is no consensus as to which category is preferred in terms of stratifying patients to follow a certain algorithmic path. It is this lack of a universal classification system that has prevented development of algorithms in the past and this remains true today. Secondly, there is a great deal of variation in hernia repair technique that differs among institutions and surgeons, based on individual operator preference, experience, and available resources. What may be an acceptable approach at one institution may be deemed outdated, less desirable, or even impossible at another. Finally, there is so much nuance regarding incisional hernias in transplant patients - hernia size and location, degree of immunosuppression, comorbidities, loss of domain, and history of previous surgeries and hernia repairs to name a few - that there are infinite possible approaches to repair. Algorithms fail to be useful when they are too convoluted. This sentiment is best stated by Malangoni and Rosen in the 20th Edition of the Sabiston Textbook of Surgery: “The absence of a universal classification system has hindered comparisons within the literature and at meetings, indirectly delaying meaningful conversations about repair techniques and prosthetic choice. The TNM model for cancer staging is an enviable model to strive for in hernia repair”[
While not common, some transplant patients’ hernias are so complicated, or have failed one or more biological mesh repairs, that surgeons must turn to autologous tissue flaps such as tensor fascia lata or thigh flaps. These autologous flaps were performed more frequently in the past and are now mostly of historical interest because complicated hernias are so effectively managed by biological mesh and novel methods of tissue expansion that complicated flap procedures are rarely necessary.
Multiple techniques have been described to help achieve abdominal wall closure including component separation, Gortex patch, use of biologic mesh (as described above), autologous flaps, and more recently abdominal wall transplantation. Abdominal wall transplantation, more commonly known as abdominal wall vascularized composite allograft (AW-VCA), is a modern alternative to abdominal wall closure which is typically reserved for truly complex defects. Utilization of AW-VCA can be separated into three categories: (1) patients receiving AW-VCA in conjunction with intestinal transplant; (2) patients receiving AW-CVA who already have a visceral organ transplant such as liver, kidney, or pancreas; and (3) AW-CVA performed as an isolated soft tissue transplant, which has shown promise in cadaver models. It is important to note that in non-transplant patients performing AW-VCA will subject patients to lifelong immunosuppression. On the contrary, for transplant patients, they are already immune suppressed.
AW-VCA can be either partial or full-thickness. In full-thickness transplants, the abdominal wall - including the peritoneum, rectus abdominis muscle(s), and variable amounts of oblique muscle, as well as skin and soft tissue - are harvested en bloc. Partial-thickness reconstruction involves vascularized or non-vascularized fascia in patients with adequate skin cover, but insufficient or inadequate fascia[
Two techniques have been described for abdominal wall transplants. In the conventional method, blood supply from the donor is taken from the inferior epigastric vessels, which are left in continuity with the femoral and iliac vessels and then anastomosed to the recipient’s common iliac artery and vein[
Levi’s group in 2003 was the first group to report their experience in a nine-case series of abdominal wall transplants[
Postoperative immunosuppression protocols are center-specific. These regimens commonly include antibody induction with maintenance therapy using tacrolimus and/or mycophenolate mofetil. Steroids may also be used during maintenance therapy. One study noted a rejection rate of 17.7% among a cohort of 17 patients[
Since the results published by Levi
To date, there is no literature showing AW-VCA being performed outside of transplant patients as an isolated procedure. The application of isolated AW-VCA (without viscera) has significant potential in patients with large abdominal wall defects including multiple prior surgeries or trauma patients with profound loss of domain. These patients are often plagued by poor functional status and have undergone multiple attempts at repair. There is, however, some thought that the risks of lifelong immunosuppression outweigh the benefits of AW-VCA transplantation, which is in part why AW-VCA as an isolated soft tissue transplant has not yet been performed.
While AW-VCA is a solution for patients with profound domain loss, the transplanted abdominal walls are essentially defunctionalized mechanical retainers of abdominal contents. These denervated transplants lack all motor function which leads quickly to atrophy, fibrosis, and loss of strength. Thus, while the patient may have a vascularized abdominal wall, he or she may have significant physical dysfunction and deformity.
In cases where innervated AW-VCA have been attempted, innervation is often unsuccessful or incomplete. From promising results in rat models, there have been multiple cadaver studies describing innervated AW-VCA to preserve both motor and sensory functions. Using a component separation technique involving the external oblique, the thoracolumbar nerves can be isolated from the donor to allow for the AW-VCA to retain both sensation and motor function[
Management of incisional hernia remains very complex, even more so in the post-transplant population. When planning any hernia repair in this patient population, one must consider patient comorbidities and risk factors, hernia morphology, and surgeon experience. Furthermore, a multidisciplinary approach should be used regarding each patient’s immunosuppression regimen, ideally including a transplant pharmacologist. While a variety of repair options exist, it has not been possible to create an algorithmic approach to such a heterogeneous population. Therefore, each patient must be approached systematically to determine the most appropriate repair. Lastly, AW-VCA is an option for very complex defects or in patients with significant loss of domain, and new techniques may allow innervation in the transplanted abdominal wall.
Made substantial contributions to the literature review, writing, and editing of this manuscript: Singh D, Holton L, Antognoli L, Choudhry S
Performed image creation and formatting: Antognoli L
Performed table creation and formatting: Choudhry S
Not Applicable.
None.
Singh D is the consultant to 3M-KCI, Allergan, and Gore; Holton L is the consultant to 3M-KCI, Allergan, and Stryker; Antognoli L and Choudhry S have no conflicts of interest.
Not Applicable.
Not Applicable.
© The Author(s) 2020.