Omentum prevents intestinal adhesions to mesh graft in abdominal infections and serosal defects

The increased angiogenic capacity and decreased inflammatory response when a mesh is used in combination with an omental flap. A prospective experimental study

BACKGROUND

The use of a surgical mesh for abdominal wall reconstruction is well established and has been used for long with minor complications, whereas the omental flap has been used for decades in reconstructive surgery.

AIM

To demonstrate the increased angiogenic capacity and the reduced inflammatory markers of a synthetic mesh when used in combination with an omental flap. Furthermore, we compare two independent meshes when used alone or in combination with the omental flap.

MATERIALS AND METHODS

Twenty-eight rats were included in the study. To determine the effect of using an omental flap under two different meshes, the animals were separated into four groups, i.e., group A (flap + mesh 1), group B (flap + mesh 1 + silicone), group C (flap + mesh 2), and group D (flap + mesh 2 + silicone). A silicone sheet was placed as a barrier between the mesh and the flap. All groups were sacrificed 8 weeks post-operatively.

RESULTS

The use of a silicone sheet barrier between any of the two synthetic meshes and the omental flap in an abdominal wall defect is accompanied by a markedly reduced angiogenesis in terms of a cluster of differentiation (CD)-34 (p < 0.001) and factor VIII (p = 0.0012) and by increased inflammatory response CD-68 (p = 0.0024) and visual scoring (p < 0.001).

CONCLUSIONS

Τhe increased angiogenic capacity and the reduced inflammatory markers of a synthetic surgical mesh when used in combination with an omental flap make it a useful option in the reconstruction of an abdominal wall defect on a large or contaminated wound.

Application of omental interposition to reduce pancreatic fistula and related complications in pancreaticoduodenectomy: A propensity score-matched study

BACKGROUND

The life-threatening complications following pancreatoduodenectomy (PD), intra-abdominal hemorrhage, and postoperative infection, are associated with leaks from the anastomosis of pancreaticoduodenectomy. Although several methods have attempted to reduce the postoperative pancreatic fistula (POPF) rate after PD, few have been considered effective. The safety and short-term clinical benefits of omental interposition remain controversial.

AIM

To investigate the safety and feasibility of omental interposition to reduce the POPF rate and related complications in pancreaticoduodenectomy.

METHODS

In total, 196 consecutive patients underwent PD performed by the same surgical team. The patients were divided into two groups: An omental interposition group (127, 64.8%) and a non-omental interposition group (69, 35.2%). Propensity score-matched (PSM) analyses were performed to compare the severe complication rates and mortality between the two groups.

RESULTS

Following PSM, the clinically relevant POPF (CR-POPF, 10.1% vs 24.6%; P = 0.025) and delayed postpancreatectomy hemorrhage (1.4% vs 11.6%; P = 0.016) rates were significantly lower in the omental interposition group. The omental interposition technique was associated with a shorter time to resume food intake (7 d vs 8 d; P = 0.048) and shorter hospitalization period (16 d vs 21 d; P = 0.031). Multivariate analyses showed that a high body mass index, nonapplication of omental interposition, and a main pancreatic duct diameter < 3 mm were independent risk factors for CR-POPF.

CONCLUSION

The application of omental interposition is an effective and safe approach to reduce the CR-POPF rate and related complications after PD.

Partial Versus Total Omentectomy in Patients with Gastric Cancer: A Systemic Review and Meta-Analysis

Background: Surgical treatment is the key to cure localized gastric cancer. There is no strong evidence that supports the value of omentectomy. Thus, a meta-analysis was conducted to compare the safety and efficiency of partial and total omentectomy in patients with gastric cancer. Methods: PubMed, Embase, and Cochrane Library databases were searched. All studies that compared total and partial omentectomy as treatments for gastric cancer were included. The primary outcomes were patients' overall survival and disease-free survival, while the secondary outcomes were perioperative outcome and postoperative complications. Results: A total of nine studies were examined, wherein 1043 patients were included in the partial omentectomy group, and 1995 in the total omentectomy group. The partial omentectomy group was associated with better overall survival (hazard ratio: 0.80, 95% CI: 0.66 to 0.98, p = 0.04, I² = 0%), shorter operative time, and lesser blood loss than the total omentectomy group. In addition, no statistically significant difference was observed in the number of dissected lymph nodes, length of hospital stays, complication rate, and disease-free survival. Conclusions: Our results show that, compared with total omentectomy in gastric cancer surgery, partial omentectomy had non-inferior oncological outcomes and comparable safety outcomes.

Post-Surgical Peritoneal Scarring and Key Molecular Mechanisms

Post-surgical adhesions are internal scar tissue and a major health and economic burden. Adhesions affect and involve the peritoneal lining of the abdominal cavity, which consists of a continuous mesothelial covering of the cavity wall and majority of internal organs. Our understanding of the full pathophysiology of adhesion formation is limited by the fact that the mechanisms regulating normal serosal repair and regeneration of the mesothelial layer are still being elucidated. Emerging evidence suggests that mesothelial cells do not simply form a passive barrier but perform a wide range of important regulatory functions including maintaining a healthy peritoneal homeostasis as well as orchestrating events leading to normal repair or pathological outcomes following injury. Here, we summarise recent advances in our understanding of serosal repair and adhesion formation with an emphasis on molecular mechanisms and novel gene expression signatures associated with these processes. We discuss changes in mesothelial biomolecular marker expression during peritoneal development, which may help, in part, to explain findings in adults from lineage tracing studies using experimental adhesion models. Lastly, we highlight examples of where local tissue specialisation may determine a particular response of peritoneal cells to injury.

Biologic versus Synthetic Mesh Reinforcement: What are the Pros and Cons?

Preserving patients' native tissues has posed many challenges for surgeons. Increased life expectancy is leading to a proportionately older surgical population with weaker tissues. The growing population of morbidly obese patients in addition to those with multiple comorbidities which influence the native strength and perfusion of tissues compounds the surgeon's challenge. Certainly, there is a rising demand for materials to replace or augment a patient's native tissue when it has been compromised. Over time, the number of products available has increased substantially. The ideal substitute, however, is debatable. The manufacturing and processing of these materials has become more complex and this has resulted in a significant increase in cost. The composition of the mesh, clinical scenario, and operative technique all interact to impact the long-term results. Surgeons require a thorough understanding of these products to guide proper selection and use, to ensure optimal outcomes for patients, and to properly steward financial resources. This review will outline the properties of commonly used materials, highlighting the strength and weakness of each. It will then discuss recommendations regarding mesh selection, coding, and reimbursement. While general principles and trends can be highlighted, further studies of biologic versus synthetic meshes are clearly necessary.

Foreign body reaction associated with PET and PET/chitosan electrospun nanofibrous abdominal meshes

Electrospun materials have been widely explored for biomedical applications because of their advantageous characteristics, i.e., tridimensional nanofibrous structure with high surface-to-volume ratio, high porosity, and pore interconnectivity. Furthermore, considering the similarities between the nanofiber networks and the extracellular matrix (ECM), as well as the accepted role of changes in ECM for hernia repair, electrospun polymer fiber assemblies have emerged as potential materials for incisional hernia repair. In this work, we describe the application of electrospun non-absorbable mats based on poly(ethylene terephthalate) (PET) in the repair of abdominal defects, comparing the performance of these meshes with that of a commercial polypropylene mesh and a multifilament PET mesh. PET and PET/chitosan electrospun meshes revealed good performance during incisional hernia surgery, post-operative period, and no evidence of intestinal adhesion was found. The electrospun meshes were flexible with high suture retention, showing tensile strengths of 3 MPa and breaking strains of 8-33%. Nevertheless, a significant foreign body reaction (FBR) was observed in animals treated with the nanofibrous materials. Animals implanted with PET and PET/chitosan electrospun meshes (fiber diameter of 0.71 ± 0.28 µm and 3.01 ± 0.72 µm, respectively) showed, respectively, foreign body granuloma formation, averaging 4.2-fold and 7.4-fold greater than the control commercial mesh group (Marlex). Many foreign body giant cells (FBGC) involving nanofiber pieces were also found in the PET and PET/chitosan groups (11.9 and 19.3 times more FBGC than control, respectively). In contrast, no important FBR was observed for PET microfibers (fiber diameter = 18.9 ± 0.21 µm). Therefore, we suggest that the reduced dimension and the high surface-to-volume ratio of the electrospun fibers caused the FBR reaction, pointing out the need for further studies to elucidate the mechanisms underlying interactions between cells/tissues and nanofibrous materials in order to gain a better understanding of the implantation risks associated with nanostructured biomaterials.

[Tissue integration of various silicone-coated polypropylene surgical mesh]

INTRODUCTION/AIM

Laparoscopic ventral hernia repair requires a surgical mesh implanted in intraperitoneal position. The combined, double layer meshes are promising in animal models as well as in human practice. The aim of this study was to compare the biological behaviour of two different textured silicone covered polypropylene mesh.

MATERIALS AND METHODS

3 × 4 cm big full thickness defect of the abdominal wall was created in New Zealand White rabbits. The defect was covered in 20 animals with a polypropylene mesh with laminar silicone layer on the visceral surface (LSPP), while the remaining 20 cases the defects were covered with a macroporous textured silicone impregnated polypropylene mesh (MSPP). Intraperitoneal adhesion formation and tissue ingrowth in the meshes were investigated. Immunohistochemistry was used to detect proliferation activity (Ki-67), neovascularization (VEGF), and to visualize mesothelial layer (CK) over the mesh. Scanning electron microscopy was used to investigate the visceral surface of the meshes.

RESULTS

While intraperitoneal adhesion formation showed no difference after 1 week, LSPP mesh induced significantly less adhesions after 21 days. The Ki-67 positivity was significantly lower and the number of the VEGF positive cells increased with time in the MSPP group, this was missing in the LSPP group. The thin neoperitoneum layer was detected over MSPP mesh only with CK antibody.

CONCLUSION

The material and texture of the mesh are responsible for tissular incorporation which is in accordance with the generated foreign body reaction.

A strategy for treatment of giant omphalocele

BACKGROUND

The management of giant omphalocele (GO) presents a major challenge to pediatric surgeons. Current treatment modalities may result in wound infection, fascial separation, and abdominal domain loss. We report a GO infant who required a delayed closure and was managed using sterile incision drape and polypropylene mesh.

METHODS

A 3080 g full-term female infant was born with a GO. The skin was dissected from the fascia circumferentially without opening the amniotic sac and the peritoneum. Subsequently, two polypropylene meshes of 10 x 10 cm in diameter were sutured to each other. Inner surface of the mesh silo was covered with sterile incision drape. This texture was sutured to the fascial margin. Then, the skin was sutured to the mesh and the silo was closed from the side and above. On the 4th day the reduction was started using thick sutures without anesthesia. This procedure was repeated on every 3rd day. When it came closer to the skin margins, constriction was performed using right angle clamps, each time placed 2 cm proximally to the previous sutures in a circular manner. Silo was removed easily and the skin, subcutaneous layers, and fascia were then approximated on the 42nd day.

RESULTS

The postoperative course was uneventful and the infant was well with left inguinal hernia repaired in the 3rd month.

CONCLUSION

The method we used can be performed at bedside and without the application of anesthesia, but should be tried on more patients to determine its effect.

Degradation of mesh coatings and intraperitoneal adhesion formation in an experimental model

BACKGROUND

In laparoscopic ventral hernia repair a mesh is placed in direct contact with the viscera, often leading to substantial adhesions. In this experimental study the ability of different coated and uncoated meshes to attenuate adhesion formation was examined.

METHODS

Six commercially available meshes were placed intraperitoneally against a closed peritoneum in rats: Prolene (polypropylene), Timesh and Ultrapro (polypropylene composites with titanium and polyglecaprone respectively), Proceed and Parietex Composite (polypropylene and polyester meshes coated with a layer of cellulose and collagen respectively) and C-Qur (polypropylene mesh coated with a layer of omega-3 fatty acids). Adhesions and incorporation were evaluated macroscopically and microscopically after 7 and 30 days.

RESULTS

Parietex Composite and C-Qur significantly reduced adhesion formation at 7 days' follow-up compared with all other meshes. By 30 days, this effect had diminished as a significant increase in adhesions together with phagocytosis of the coating was seen for all meshes with layered coatings (Proceed, Parietex Composite and C-Qur. Incorporation was insufficient for all meshes.

CONCLUSION

The absorbable layers of Parietex Composite and C-Qur reduce adhesion formation to intraperitoneal mesh in the short term, but the effect diminishes and phagocytosis of absorbable coatings may contribute to adhesion formation.

Omentum-preserving gastrectomy for early gastric cancer

BACKGROUND

The omentum has variable functions in surgical procedures. Nevertheless, there is very little information about the effect of omentum on abdominal complications after gastrectomy. The purpose of the present study was to determine the outcome of omentum-preserving gastrectomy for early gastric cancer.

METHODS

We evaluated 1,116 patients who had a gastrectomy for early gastric cancer between the years 2004 and 2006; 992 patients underwent conventional gastrectomy (CG), and 124 patients had an omentum-preserving gastrectomy (OPG). These cases were analyzed retrospectively. The early and late abdominal complications were compared between the CG and OPG groups.

RESULTS

The results of the study show no significant differences between the early abdominal complications in the CG and OPG groups. However, the late abdominal complication rate in the OPG was significantly lower than the CG (p = 0.026). The most common risk factor associated with early abdominal complications was type of operation. The combination of CG and early abdominal complication represented a statistically significant risk for late abdominal complications (p = 0.026, 0.031 respectively).

CONCLUSION

The findings of this study demonstrate that the omentum-preserving gastrectomy in the treatment of early gastric cancer showed a lower rate of abdominal complications compared to the conventional gastrectomy.