Definition and Overview
The medical use of prosthetic materials, such as a mesh, has revolutionised the treatment of a variety of diseases. Hernias of varying sizes can now be repaired with minimal complications, and mesh repairs of this condition have produced more favourable results, specifically with regard to recurrence, compared to primary closure. Resection of large areas of the abdominal or chest wall, which in the past was deemed high risk due to significant morbidities associated with such operations, can now be performed with better outcomes. Techniques for reconstruction of different defects, which utilise these prosthetic materials, have evolved, resulting in improved results and survival.
However, one of the major risks involved with the insertion of prosthetic materials in the body is the development of infection. Severe infections may necessitate their removal, resulting in failed reconstruction and a number of associated complications.
Who Should Undergo and Expected Results
The most common use of a mesh remains to be for the repair of hernias, a defect in a body cavity resulting in the protrusion of the internal organs. It is usually found in the inguinal area, but can also be found in any part of the abdominal wall, even the diaphragm. A mesh is used to cover and reconstruct the defect. Aside from hernia repair, mesh and other prosthetic materials may also be used in the reconstruction of defects of the chest wall.
Infections in these cases can generally be managed with the use of appropriate antibiotics. Even in patients who have undergone insertion of a mesh or other prosthetic materials, infection is managed conservatively, if possible. Drainage of the infection and serial debridement may be attempted, along with irrigation or lavage. Partial excision of the mesh with the use of vacuum-assisted or negative pressure wound therapy has also been performed. These techniques have been effective to some extent, but may be associated with the development of chronic infection, fistulas, or sinuses. The removal of prosthetic materials is reserved for severe infections that do not respond to adequate antimicrobial therapy and for recurrent or chronic infections.
Mesh infections may have a delayed presentation, usually several months or even years after the initial operation. A combination of local and systemic symptoms is noted. An abscess or a draining sinus may also develop at the operative site.
For cases of mesh infections, it is first important to determine the extent of the infection and whether or not the mesh is involved. For inguinal hernias, most infections are limited to the subcutaneous tissue and require only drainage and antibiotic therapy. However, deeper infections involving the mesh itself may require the removal of the entire mesh. In more severe infections, mesh removal should be accompanied by debridement of all tissues that are no longer viable. The hernia recurs after mesh removal, and this can be managed after a minimum of 6 months, usually by another approach (preperitoneal).
For ventral hernias, management can be complicated. Drainage is important, and the wound may have to be opened. Sutures and excess mesh material should be removed, as these may be a cause for the development of a draining sinus. The mesh is then allowed to granulate. However, if the mesh extrudes through the wound, it may be necessary to remove the entire mesh.
Another condition that is difficult to manage is the development of enteric fistulas in patients who have undergone mesh repair of a ventral hernia. Extra mesh material, which folds over and becomes redundant, may erode through the intestinal walls, resulting in the formation of a fistula. When this occurs, the mesh surrounding the fistula tract, as well as part of the involved intestine, may have to be removed.
How is the Procedure Performed?
The removal of an implanted prosthetic material is typically difficult. The inflammatory reaction elicited by the mesh and the infection results in an altered anatomy, making it difficult to identify tissue planes and normal structures. Meticulous dissection is thus important in these cases.
The incision for the removal of a mesh is generally the same as the one performed during implantation. The surgeon goes through the same planes until the mesh is reached. Exposure of the entire mesh is important to ensure that no residual prosthetic material is left. All the sutures are then removed, and the mesh is gently separated from the underlying tissues. If infection is extensive, debridement of surrounding tissues may be necessary. In these cases, hemostasis is very important, as going through inflammatory tissues can result in significant bleeding. Coverage can be a problem, and depends on the resultant defect. Definitive closure is occasionally achieved by performing a full-thickness flap.
Possible Risks and Complications
For cases of infection, complete removal of the mesh, combined with proper antibiotic therapy, usually facilitates resolution of the infection. However, the removal of the prosthetic material can result in serious complications. The surgery for mesh removal is often challenging, and the inability to identify normal structures can lead to morbidity, especially around the spermatic cord.
Because of the lack of structural support, the hernia expectedly recurs. In some cases of inguinal hernias, enough fibrosis has already occurred such that the hernia no longer recurs, and no further management is necessary. For ventral hernias, on the other hand, mesh removal can produce a large defect in the abdominal wall. The subsequent defect can be closed using different techniques, such as primary closure, component separation, or implantation of a biologic mesh; however, these are not always possible, and some cases end up with an open abdominal wound, which necessitates complex and specialised wound management.
- Abdominal Wall Hernias: Principles and Management http://laparoscopy.blogs.com/preventionmanagement3/2010/07/pathogenesis-of-surgical-site-infection-ssi.html http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3641368/