Mesh erosion into skin following laparoscopic totally extraperitoneal (TEP) inguinal hernia repair

Discussion

Mesh erosion and migration are rare complications of TEP hernia repair, and present as a chronic and gradual process. There is a latent period between hernia repair and the onset of erosion, which varies from several months to years.5 Mesh erosion in human tissues is a well-known phenomenon, with numerous reports on all current polymers after different hernia repair procedures.6 Rapid remodelling of adjacent tissues occurs after mesh implantation, and erosion occurs in a setting of tensile forces acting on the mesh, with physical contact between mesh and viscera leading to chronic inflammation.4 6 Primary or secondary factors have also been implicated in mesh migration. In our case, erosion occurred 2 years after the initial TEP repair.

Biocompatibility between the mesh and the host is particularly important for its intended function, which is to induce intense fibrosis without eliciting any undesirable local or systemic effects in the host.7 Mesh implantation induces a foreign-body reaction in host tissues, resulting in persistent chronic inflammation at the mesh-tissue interface.6 The degree of inflammation is influenced by the biomaterial composition of the mesh (the type of polymer, material weight, filament structure and pore size).7 Even with improvements in mesh technology, there is a lifetime risk of mesh erosion.6 The mesh used in our patient was made from polypropylene in a non-woven matrix, which is the most preferred biomaterial for hernia repair.

Mesh migration after hernia surgery can be attributed to primary mechanical and secondary inflammatory factors.8 Primary mesh migration is the displacement of a mesh along the path of least resistance because of several factors, including technical factors, such as inadequate preperitoneal space creation, improper placement of the mesh, mesh folding and curling, or external displacing forces.5 8 Secondary mesh migration occurs gradually over a period of months and years because of gradual movement of the mesh through transanatomical planes caused by foreign body-tissue reaction.8 A short latent period (<1 year) between hernia repair and the occurrence of mesh erosion usually indicates technical errors in initial hernia repair and mesh placement.5 Therefore, the late presentation in our case suggests the possibility of secondary mesh migration, although we could not completely exclude primary mechanical factors as its aetiology. The foreign body-tissue reaction caused the mesh to move towards the path of least resistance, which was the superficial inguinal ring, and eventually eroded through the skin. Initially, we thought the mesh was infected from the perforated diverticulitis, as there were features suggestive of an intraperitoneal extension of the left inguinal abscess on CT, as well as sigmoid diverticular disease on colonoscopy. However, diagnostic laparoscopy performed during surgery did not reveal any evidence of inflammation or adhesions near the mesh site, making this possibility less likely. The eroded mesh was completely removed with the culture showing no growth, possibly because of repeated antibiotic treatments.

Inadequate mesh fixation was suggested as a possible cause of mesh migration in our case because the mesh was not fixed with a tacker during the previous repair. However, mesh fixation during TEP inguinal hernia repair remains controversial. Several randomised controlled trials (RCTs) had failed to demonstrate the advantage of mesh fixation in terms of mesh displacement and recurrence.9 10 Two meta-analyses of six RCTs further demonstrated that non-fixation of meshes is a safe alternative that does not significantly increase the risk of recurrence.11 12 Based on strong evidence, the HerniaSurge guidelines endorsed by various international hernia societies recommend that mesh fixation is unnecessary in almost all cases of TEP repair.6

The treatment strategy in this case was to excise the migrated parts of the mesh. Ideally, a combination of complete mesh removal and intravenous antibiotics would be the best strategy to prevent persistent mesh infections. However, complete surgical excision of the mesh along with the unmigrated parts can be challenging, with high complication rates, as other parts of the mesh may be firmly fixed due to fibrosis. The extent of mesh infection influences decision making for complete mesh removal. In our case, diagnostic laparoscopy was performed to assess any extraperitoneal collection or intraperitoneal extension. The decision was to make an elliptical incision on the wound, to remove both the infected tissue and migrated mesh. The wound was debrided and irrigated to remove infectious debris. The patient was started on oral antibiotics, with the wound laid open and managed with daily dressing for 2 weeks. After good granulation tissue was observed, the patient underwent secondary suturing in the operating theatre. The patient’s outcome was good, as there was good wound healing and high patient satisfaction.

Mesh migration and skin erosion following TEP inguinal hernia repair is rare, but may have significant consequences. Definitive diagnosis can be difficult in cases where the time to event is up to 2 years. A high index of suspicion is required when diagnosing any patient who presents with an unexplained groin abscess following ipsilateral TEP repair. CT scan should be performed early for diagnosis and assessment. Removal of the migrated portion of the mesh, antibiotic therapy and delayed wound closure are strategies for the successful treatment of this complication.