Ten-Year Retrospective Analysis of Incisional Herniorrhaphy Following Renal Transplantation FREE

Incisional hernias may occur following any abdominal operation and are defined as the separation of muscle and fascia at a previous incision, with the peritoneum, subcutaneous tissue, and skin remaining intact.¹ Incisional hernias are believed to develop in 1% of patients who undergo uncomplicated surgical procedures, in 10% of patients who subsequently develop a wound infection, and in more than 30% of patients who have undergone a prior incisional hernia repair.^2- 3 More than half of incisional hernias appear within 6 months after surgery, approximately 75% within 2 years, and 97% within 5 years.⁴

Studies^5- 6 examined risk factors that predispose patients to developing incisional hernias and identified multiple factors, including obesity, diabetes mellitus, advanced age, malnutrition, smoking history, and infection. Similarly, studies analyzed different surgical techniques for the treatment of incisional hernias, including primary repair, laparoscopic vs open techniques,⁷ different prosthetic meshes and biologic implants,^8- 10 and autologous reconstruction with component separation.^6,11- 15 Ultimately, the precise risk factors and ideal modalities of treatment and prevention of complications following incisional herniorrhaphy remain unclear and are most challenging in the complex population of patients who have undergone organ transplantation, especially renal transplants.

However, there is limited evidence about the risk factors and treatment of incisional hernias in patients following renal transplantation, as these patients are likely to have increased risk of developing hernias and postoperative complications because of corticosteroid use and immunosuppressive therapy.¹⁶ Specifically, while some studies^17- 18 demonstrated an association of incisional hernia development with the use of sirolimus therapy, other studies^19- 20 failed to corroborate these findings and instead reported an association with the use of mycophenolate mofetil therapy.^17- 20 In addition, patients following renal transplantation are likely to be at greater risk not only because of their immunosuppressive drug regimens but also because of long-term dialysis, diabetes, and uremia.^21- 22

This study was undertaken because of the complex nature of this unique patient population and the paucity of literature addressing the development of this frequent and potentially catastrophic complication. We aimed to identify whether specific risk factors, including immunosuppressive therapy, correlated with the development of incisional hernias and to evaluate what associations existed between these risk factors and postoperative complications.

All patients undergoing renal transplantation or combined renal-pancreas transplantation at the University of California, San Francisco, between January 1, 1995, and December 31, 2005, were evaluated for the development of an incisional hernia based on the presence of Current Procedural Terminology coding for treatment of the condition. All patients who had undergone renal transplantation and developed an incisional hernia during the designated period were included in the study. Following institutional review board approval, a retrospective medical record review was performed among 42 patients who satisfied the inclusion criteria.

Identified were comorbidities (including smoking history), preoperative history and physical examination findings, size of hernias, and postoperative outcomes. All hernias and repairs were quantified and compared for size, infection, recurrence, and other complications. Operative reports were reviewed for perioperative antibiotic use, operative technique, and operating surgeon. In addition, each patient's immunosuppressive drug regimen was analyzed.

Univariate analysis of variables was performed to characterize the study population. χ² Test was performed to examine differences in proportions of patients with infection or recurrence. t Test was performed assuming unequal variances, with significance set at P < .05. All statistical tests were performed using commercially available software (SPSS 17; SPSS Inc, Chicago, Illinois).

From January 1, 1995, to December 31, 2005, a total of 3289 patients underwent renal transplantation (1915 cadaveric donor renal, 1136 living related donor renal, and 238 combined renal-pancreas) at the University of California, San Francisco. Among them, 42 patients (1.3%) developed an incisional hernia (Table 1). The mean (SD) age of patients was 49.6 (9.9) years; 27 were men and 15 were women. Twenty-six patients received cadaveric donor renal transplants, 12 patients received combined renal-pancreas transplants, and 4 patients received living related donor renal transplants. Diabetes was a frequent cause of end-stage renal disease (16 patients), followed by polycystic kidney disease (6 patients), focal segmental glomerular sclerosis (3 patients), hypertension (2 patients), Alport syndrome (2 patients), and IgA nephropathy (2 patients), with 11 patients having lupus or glomerulonephritis. Other comorbidities included hypertension (32 patients), hepatitis C (4 patients), smoking history (3 patients), atrial fibrillation (3 patients), and coronary artery disease (2 patients).

Immunosuppressive drug regimens included combinations of prednisone (40 patients), mycophenolate mofetil (33 patients), cyclosporine (32 patients), tacrolimus (25 patients), sirolimus (22 patients), and azathioprine (4 patients). These results are summarized in Table 2.

The median period from renal transplantation to incisional hernia repair was 457 days (mean, 1016 days; range, 10-4812 days). Among 62 hernias repaired, 32 occurred through midline laparotomy incisions, 27 through right lower quadrant incisions, and 3 through left lower quadrant incisions (Table 2). Using various techniques, hernia repairs were performed on average 36.4 months following transplantation. Fifteen patients underwent primary repair of 18 hernias, 24 patients underwent mesh repair as their initial treatment of 38 hernias, and 3 patients underwent component separation in 6 hernias with porcine small intestine submucosa in 2 hernias and polypropylene mesh in 1 hernia as the initial repair. The mean (SD) length of stay after hernia repair was 4.8 (3.9) days (range, 1-21 days).

Seven patients with primary repair had incisional hernia recurrence and 6 of these 7 underwent subsequent repair with mesh (3 patients), component separation (2 patients), or primary repair (1 patient). Of 6 patients undergoing a second hernia repair, 1 had a second recurrence, which was subsequently repaired with mesh.

Of 24 patients having incisional hernias repaired with mesh, 7 patients had recurrences, which were repaired with mesh (4 patients), primary repair (2 patients), and component separation and polypropylene mesh (1 patient). Among 24 patients, 1 patient had 4 recurrences, with the second recurrence repaired primarily and the 3 subsequent recurrences repaired using mesh. Two patients developed infections requiring mesh removal, temporary repair with polyglactin mesh, and then definitive mesh repair at a later date. For statistical analysis, these were counted as 2 separate recurrences for each patient.

No recurrences developed in hernias repaired with component separation as the primary repair (3 hernias) or as a secondary operation (3 hernias). Twenty-nine patients underwent repair by transplant or general surgeons, with 12 recurrences (41%), and 13 patients underwent repair via a joint effort by transplant and plastic and reconstructive surgeons, with 2 recurrences (15%). Hernia sites were similar among repairs performed by transplant surgeons alone or in conjunction with the general surgery service. Among hernias repaired by transplant and plastic and reconstructive surgeons, 7 were located in the right lower quadrant and 6 were midline laparotomy hernias.

Overall, 14 patients (33%) developed an incisional hernia recurrence, with 3 patients experiencing 2 recurrences and 1 patient experiencing 4 recurrences. Seven of 15 patients had recurrences following primary closure, and 7 of 24 patients treated initially with mesh repair developed recurrences. Complications included 4 patients who developed cellulitis at the surgical site that resolved with oral antibiotics, 2 patients who required reoperation for removal of infected mesh, and 1 patient who had an abscess that required drainage and intravenous antibiotics. Of 7 patients who developed an infection, 2 underwent primary repair and 5 underwent repair with mesh. Six of 14 patients who developed recurrences had simultaneous infection, which was subsequently found to be a significant risk factor for incisional hernia repair failure regardless of whether it was performed primarily or secondarily (P < .01).

Using univariate analysis, several variables were analyzed for association with infection and recurrence following incisional hernia repair (Table 3). Increased risk of infection was associated with male sex, mesh repair, tacrolimus use, sirolimus use, hypertension, smoking history, diabetes, and hernia area exceeding 100 cm². Increased risk of recurrence was associated with male sex, primary repair, tacrolimus use, smoking history, and diabetes. Risk of recurrence was not associated with component separation as primary repair or in secondary operations (χ² = 3.40, P = .09).

Using univariate analysis, infection was associated with incisional hernia recurrence (odds ratio, 1.54; 95% confidence interval, 0.31-7.63; P = .44) when analyzing all recurrences separately. Infection was a significant risk factor for failure of an initial or prior herniorrhaphy (odds ratio, 15.00; 95% confidence interval, 1.54-146.02; P < .01), as 6 of 7 infections occurred in patients who subsequently developed a recurrence.

While numerous investigations examined the risk and development of incisional hernias following abdominal operations, incisional hernias in patients following renal transplantation are less well understood. In our study, the incidence of incisional hernias was 1.3%, which is lower than what has been previously reported. This is likely a consequence of our selection criteria based on Current Procedural Terminology codes, as patients who did not undergo repair or who underwent treatment at another institution would not have been included. The incidence of incisional hernias among patients receiving a combined renal-pancreas transplant (5.0%) was dramatically higher than that among patients receiving a cadaveric donor renal transplant (1.3%) or a living related donor renal transplant (0.4%). Before 2000, only 3 patients who had undergone combined renal-pancreas transplantation developed incisional hernias; none were taking sirolimus. Following the addition of sirolimus to the immunosuppressive drug regimens of all patients undergoing combined renal-pancreas transplantation in 2000 at our institution, 9 patients developed an incisional hernia from 2000 to 2005. This may further implicate sirolimus as a potential risk factor for the development of incisional hernias but may also suggest that diabetes or a midline laparotomy approach may have a role as well. Given the limited number of patients undergoing combined renal-pancreas transplantation who developed incisional hernias, this unique cohort of patients remains to be further elucidated.

Although our study demonstrated that several factors were associated with increased risk of postoperative infection or incisional hernia recurrence, our results did not necessarily corroborate the findings of some prior studies. Some investigations showed increased risk of incisional hernias in patients who undergo renal transplantation through a lateral Gibson incision vs a midline laparotomy incision.²⁰ In our study, the incidence of incisional hernias was essentially the same regardless of whether a midline approach or a right or left lower quadrant approach was used. While other studies^21,23 demonstrated increased incidence of incisional hernias among patients with a smoking history, patients with diabetes, and patients with polycystic kidney disease as the underlying cause of end-stage renal disease, we did not find this to be the case in our cohort. However, although smoking history and diabetes were not associated with initial development of an incisional hernia, both were associated with increased risk of a postoperative infection or a recurrence.

Prior studies^18,20 of long-term corticosteroid use and immunosuppressive therapy found the use of mycophenolate mofetil and sirolimus to be significant risk factors for the development of incisional hernias and for complications following repair. As such, sirolimus is routinely stopped before herniorrhaphy at our institution, which likely explains why sirolimus use was not associated with recurrences in our cohort. However, sirolimus use and tacrolimus use were associated with increased risk of developing postoperative infections, which was not observed with mycophenolate mofetil use. While our study confirmed increased risk of complications following repair of an incisional hernia with certain immunosuppressive drug regimens, we did not demonstrate a causal relationship between the use of immunosuppressants and the incidence of incisional hernias. Neither sirolimus use nor mycophenolate mofetil use predisposed patients to developing an incisional hernia following renal transplantation. This may be a reflection of our sample size and will require further studies for clarification.

The technique used to repair incisional hernias did not adversely affect the outcomes or the incidence of recurrences. Similar to other investigators,^21- 24 we found that permanent synthetic mesh is safe for use in patients following renal transplantation, despite the use of immunosuppressive therapy. However, in contrast to other findings,²⁵ we demonstrated increased risk of infections when mesh was used in this immunosuppressed patient population, which was not observed with alternative techniques. Consequently, mesh was used strategically only for repair of larger hernias to span defects that could not be reapproximated primarily without tension. The mean area of hernias corrected with primary repair in our cohort was 40.8 cm,² while the mean area of hernias repaired with mesh was 137.5 cm².

The overall 17% incidence (7 of 42 patients) of infections in our cohort is comparable to previous findings but underscores the need for aggressive postoperative management of infections in patients who undergo mesh repair. Any evidence of cellulitis is treated immediately with oral antibiotics, with a low threshold for initiation of intravenous antibiotics. Given that almost half of the patients who developed a recurrence had an infection, perioperative measures to prevent and treat infections will likely decrease recurrences.

While patients treated with mesh or primary repair experienced recurrences, no patients treated with component separation developed a recurrence. This also likely reflects our limited sample size, as only 6 patients in the cohort were treated by this technique; however, component separation has been the repair of choice at some institutions,²⁶ and clearly a larger sample size would be needed for further analysis. At our institution, a joint operation by transplant and plastic and reconstructive surgeons is usually performed if patients have failed a prior repair or if the defect is exceedingly large (>100 cm²). The mean area of hernias repaired as a joint effort was 216.2 cm², and that of hernias repaired by the transplant team alone was 69.6 cm².

Finally, the emergence of various biologic implants that can resist infection (unlike permanent mesh implants) has demonstrated some promising and sometimes conflicting results.^27- 28 Given the lack of data, we do not routinely use acellular dermal matrix in herniorrhaphy at our institution; however, in the setting of poor soft tissue coverage or gross contamination, such substances may have a role. Larger studies will be necessary to determine the usefulness of acellular dermal matrix in the treatment of incisional hernias among this complex patient population.

To our knowledge, our study represents the largest series of incisional herniorrhaphies performed among patients following renal transplantation. Several risk factors, including hernia size, smoking history, the presence of diabetes, sirolimus use, and tacrolimus use, were associated with adverse postoperative complications; however, no clear association was found between these risk factors and the incidence of incisional hernias. We recommend aggressive management of any postoperative infection and consideration of component separation in recurrent or large incisional hernias if a joint operation by transplant and plastic and reconstructive surgeons is available.

Correspondence: William Y. Hoffman, MD, Division of Plastic and Reconstructive Surgery, University of California, San Francisco, 505 Parnassus Ave, Ste M-593, San Francisco, CA 94143-0932 (william.hoffman@ucsfmedctr.org).

Accepted for Publication: October 12, 2009.

Author Contributions: Dr Chang and Mr Galvez contributed equally to this work. Study concept and design: Chang, Padilla, Freise, Foster, and Hoffman. Acquisition of data: Chang, Galvez, and Padilla. Analysis and interpretation of data: Chang, Galvez, Padilla, and Hoffman. Drafting of the manuscript: Chang, Galvez, and Hoffman. Critical revision of the manuscript for important intellectual content: Chang, Galvez, Padilla, Freise, Foster, and Hoffman. Statistical analysis: Chang, Galvez, and Padilla. Administrative, technical, and material support: Chang, Galvez, Freise, Foster, and Hoffman. Study supervision: Freise, Foster, and Hoffman.

Financial Disclosure: None reported.

Previous Presentations: This study was presented at the 80th Annual Meeting of the Pacific Coast Surgical Association; February 14, 2009; San Francisco, California.