Incisional hernia of the abdominal wall is a hernia formed by incomplete healing of the fascial and/or muscular layers of the abdominal wall incision, under intra-abdominal pressure, with a hernia sac that may have intact or incomplete peritoneal epithelium. The subincisional musculofascial defect of the abdominal wall can be palpated on examination or detected on imaging, and the defect may be accompanied by protrusion of intra-abdominal organs more often than not. Incisional hernia of the abdominal wall is one of the most common long-term complications after abdominal surgery and the only medically induced abdominal wall hernia, with an incidence of 2%-11%. The etiology of incisional hernia comes from both the patient’s own factors and the surgical operation [3-4]. These factors affect the patient’s tissue regeneration and healing ability and increase the chance of incisional hernia formation. ②Surgical factors: The local factors for the occurrence of incisional hernia are mainly local injury to the abdominal wall caused by surgery, hematoma formation and infection, of which infection is crucial. The peri-incisional tissue burns caused by the widespread use of electric knife, vascular and nerve tissue damage caused by rough clamping, large ligatures, forced pulling and even the formation of focal necrosis of the abdominal wall, improper suture selection, poor suture technique and poor tissue alignment affect wound healing and tension after healing, and in some patients the incision is too long and excessive tension of the incision is not used to reduce tension, which can lead to tissue tearing and total or partial splitting of the incision. Some patients have long incisions and excessive tension in the incision and failure to use reduction sutures can lead to complete or partial tearing of the incision, which are all medical factors for incisional hernia. Postoperative forceful urination and defecation; severe coughing caused by laryngitis and lung infection can cause a dramatic increase in intra-abdominal pressure, resulting in suture cutting and poor tissue healing and incisional hernia. There is a relationship between the type of incision and incisional hernia formation: longitudinal incision is easy to damage the neurovascular and transverse abdominal muscles of the abdominal wall, so the incidence of hernia is higher than that of transverse incision. In addition to clearly showing the location and size of the abdominal wall defect, the relationship between the hernia contents and intra-abdominal organs, CT or MRI can also be used to calculate the hernia sac volume to abdominal cavity volume ratio, and to assess whether the hernia has developed after reduction. It can also be used to calculate the hernia sac volume and abdominal volume ratio, and is valuable in assessing whether abdominal compartment syndrome (ACS) occurs after hernia retrieval. 2.2 Staging The development of an ideal staging method for incisional hernias is important for the selection of the repair procedure and method and the evaluation of the outcome. At present, there is no unified classification method internationally. According to the classification of incisional hernia by the European Hernia Society and in accordance with the clinical practice in China, the staging of incisional hernia should be evaluated comprehensively from the following three aspects. According to the size of the abdominal wall defect (1) small incisional hernia: the maximum diameter of the hernia ring is <3 cm; (2) medium incisional hernia: the maximum diameter of the hernia ring is 3-5 cm; (3) large incisional hernia: the maximum diameter of the hernia ring is 5-10 cm; (4) large incisional hernia: the maximum diameter of the hernia ring is 10 cm, or the ratio of the hernia sac volume to the abdominal cavity volume is >0.15 (regardless of the maximum diameter of the hernia ring). (1) Midline incisional hernia according to the location of the hernia defect: including subxiphoid incisional hernia, supraumbilical incisional hernia, infraumbilical incisional hernia, suprapubic incisional hernia; (2) lateral abdominal wall incisional hernia: including subcostal incisional hernia, inguinal incisional hernia and intercostal iliac incisional hernia. Based on whether it is a recurrent hernia classification can be divided into primary incisional hernia and recurrent incisional hernia. In recent years, some scholars have proposed marginal area hernias, which mainly refer to hernias near the rib arch, pubic bone and iliac bone. If the primary disease is not cured or the malignant tumor is not removed or palliative resection is not performed, incisional hernia without life-threatening complications such as impaction may not be considered for surgery; for patients with primary and recurrent hernias without infection, repair surgery is recommended 3 months after the last surgery. For patients with incisional infection, repair surgery is recommended 6 months (at least 3 months or longer) after the infection has been completely cured and the incision has healed. 3.2 Pre-operative preparation 3.2.1 Active management of concomitant diseases Diabetic patients should have their blood glucose controlled at about 8 mmol/L, blood pressure controlled, hypoproteinemia corrected, and chronic cough, constipation, prostatic hyperplasia and other diseases that can cause increased abdominal pressure treated before surgery. Preoperative CT, electrocardiogram, cardiac function, pulmonary function examination, intestinal preparation according to colorectal surgery, etc. Preoperative CT examination can well clarify the size of the abdominal wall defect and whether there are adhesions between it and the intestinal canal, thus providing a basis for further determining the surgical plan, whether to perform intra-abdominal repair and the size of the patch used. 3.2.2 Prophylactic antibiotics should be applied 0.5-2 hours before surgery to prevent the occurrence of postoperative infection. Patients with impaired pulmonary function should be adequately prepared and operated only after improvement of pulmonary function and blood gas analysis. For giant incisional hernia, generally speaking, surgery can be performed if there is no change in respiration or heart rate after more than 80% of the hernia contents have been retracted. When the ratio of hernia sac volume to abdominal cavity volume is >0.15, in order to prevent respiratory failure and inter-abdominal compartment syndrome after the hernia contents are retracted into the abdominal cavity, preoperative abdominal volume expansion and abdominal muscle compliance training should be performed. Most of the hernia contents can be returned preoperatively, and the abdomen can be tied with a lap band or the abdominal cavity can be expanded with a progressive artificial pneumoperitoneum. After 2 to 3 weeks of the above preparatory measures, surgery is then performed. In recent decades, especially in the last two decades, with the development and application of repair materials and repair techniques, the surgical approach to incisional hernia has undergone tremendous changes with the emergence of new surgical approaches such as hybridization technique, abdominal wall tissue structure separation technique combined with bridging repair technique, etc. 3.3.1 Simple suture repair is suitable for small and medium incisional hernias It is advisable to use nonabsorbable or slowly absorbable sutures with continuous sutures (suture length: incision length of 4:1). However, there is evidence that simple suture repair has a high recurrence rate after 5 years of surgery. In recent years, the component separation technique (CST) has been used for incisional hernias in the midline area to close and strengthen the defect and reduce tension and recurrence. 3.3.2 Artificial material repair is recommended for patients with incisional hernias of intermediate size or larger. Depending on the level of placement of the patch during abdominal wall reconstruction, it can be divided into (1) anterior abdominal wall muscle placement (onlay/overlay), (2) inter-abdominal wall defect placement (inlay), (3) posterior abdominal wall muscle (preperitoneal space) placement (sublay), and (4) intra-abdominal placement immediately adjacent to the peritoneum (IPOM/underlay). It is important to emphasize that when this type of repair is used, the patch material should have anti-adhesive properties. It should be noted that in recent years, the CST technique has been promoted by most scholars and its application is becoming more and more widespread. The CST technique allows the closure or reduction of defects, and those that cannot be closed should be closed with an anti-adhesive mesh or biopatch and covered with an ordinary mesh (onlay), so that the tension of the abdominal wall can be strengthened (reinforce), especially for those who have loose abdominal skin and need to be shaped. 3.3.3 Surgical methods: ① open surgery, applicable to all types of incisional hernia. Traditional open surgery can effectively treat incisional hernia with reliable therapeutic effect by observing under direct vision and touching the extent and degree of weakness of the abdominal wall, but it is traumatic and affects the patient more, with relatively long postoperative pain time and healing time and slow recovery of the patient. ②Laparoscopic surgery: it is the best surgical method for incisional hernia, with reliable repair and fast patient recovery with little trauma, but the patient should be transferred to open the abdomen in time if the adhesions between intestines are heavy, the intestines form dense adhesions in the abdominal wall and are difficult to be separated or if intestinal damage occurs during separation. Hybrid Technique: Hybrid technique refers to the systematic and orderly combination of lumpectomy technique and conventional open surgery technique to enhance the efficiency of surgery and the safety and effectiveness of treatment by utilizing the advantages of each. On the one hand, it can safely and quickly separate the abdominal adhesions and return the hernia contents under direct vision, reducing the probability of intestinal injury; at the same time, it is simple and quick to place the patch through a small incision in the abdominal wall, shortening the operation time. On the other hand, laparoscopic exploration of the abdominal cavity can reveal hidden defects; laparoscopic placement and fixation of the patch can be accurately positioned and the patch can be spread. This technique combines the advantages of both, while avoiding the disadvantages of each, to achieve an organic combination of open surgery and laparoscopic surgery. Bridging repair: In some elderly patients where abdominal wall tissue separation is traumatic and not conducive to recovery, or where the abdominal wall defect is too large and not in the midline for tissue separation, patch bridging can be performed to repair the defect to expand the abdominal cavity and avoid the increase in abdominal pressure after closure of the abdominal wall defect. This is done by not closing the myofascia of the hernia defect, covering the defect with a patch by Onlay, Sublay or IPOM method, with the edge of the patch overlapping the normal myofascia of the hernia ring edge by more than 5 cm, and then fixing the edge of the patch and the patch of the hernia ring edge with a double ring. 3.4 Intraoperative management Reasonable surgical operation is related to the success of the operation, the patient’s recovery and postoperative complications. ①The surgical incision should be taken as far as possible from the original incision (the laparoscope should be as far away from the original incision as possible), and in case of the thread left over from the previous operation, it should be removed as far as possible to prevent postoperative infection and sinus tract formation. ② Treatment of adhesions: adhesions between the intestinal canal and the abdominal wall in the abdominal cavity can injure the abdominal wall but not the intestinal canal. If intraoperative adhesions are found between the hernia contents and the hernia sac and hernia ring, the adhesions need to be separated, and the separation should be more than 5.0 cm beyond the edge of the defect; meanwhile, for the adhesions between the intestinal canal, if the angle is large and obstruction is not easily formed, they may not be separated, and for those with adhesive incomplete obstruction, it is recommended that they should be completely loosened For those with incomplete adhesions, complete loosening is recommended. If the intestinal canal is damaged during surgery and there is leakage of intestinal fluid, thorough disinfection and flushing should be done during surgery, and the damaged part of the intestinal canal should be sutured; if the damaged part is small intestine, e-PTFE-free material can be used for repair; if it is colon, biological material is recommended for repair. For incisional hernia less than 5 cm, the patch is generally required to exceed the edge of the defect by at least 3 cm; for incisional hernia larger than 5 cm in diameter, an overlap of at least 5 cm is required; for fixation of the mesh, the patch can be fixed with a staple gun for small incisional hernia, while for large incisional hernia, full transabdominal wall fixation should be done. The outer ring should be fixed as close to the edge as possible, with a spacing of no more than 3 cm, and another ring should be fixed at the hernia ring. The drainage tube should be placed between the mesh and the abdominal wall. If the intestinal adhesions in the abdominal cavity are heavy and a wide range of release is performed, a drainage tube should also be placed in the abdominal cavity to reduce intra-abdominal exudate and prevent inflammatory bowel obstruction. The choice of repair materials for incisional hernia repair is complex and varied, and the choice of repair materials depends on the patient’s surgical approach and intraoperative conditions. The synthetic material repair is generally recognized by clinicians and patients for its low recurrence rate, low complications, rapid recovery, and short hospitalization period. Currently, two types of patches are commonly used: absorbable and non-absorbable materials. The former is commonly used for infection, contamination, trauma or temporary closure of the abdomen, and repair of incisional hernias is currently mainly done with non-absorbable materials. Non-absorbable material patches are mainly: single species materials: mainly polyester, polypropylene, expanded polytetrafluoroethylene (e-PTFE) class 3; composite materials, that is, more than two materials, such as Bard’s Composix E/X composite patch, from polypropylene and polytetrafluoroethylene double-sided material, the former against the peritoneum the latter towards the abdominal wall to avoid intestinal adhesion: Johnson & Johnson’s Proceed consists of The PCO patch of Tyco is made of non-absorbable polyester (polyethylene terephthalene) with an absorbable hydrophilic film composed of porcine collagen, polyethylene glycol and propanetriol; absorbable biomaterial patch: the Biodesign hernia patch of COOK is made of porcine small intestine submucosa (named SIS material). (named as SIS material), and the domestic ones are Reno bio-mesh sheets made of human skin by decellularization, which are absorbable extracellular matrix and can induce the regeneration of collagen formation after being placed in the body, and belong to regenerative patches, but the long-term effect needs further observation. Polyester patches are light, soft, strong and long-lasting, but have poor resistance to infection and heavy foreign body reaction. Tuffs University reported many long-term complications, with recurrence rates as high as 34% and infection rates as high as 15%, etc. Polypropylene mesh has good histocompatibility, strong resistance to infection, and can be quickly fixed with human tissue adhesion, but the mesh is easy to adhere to organs and can produce complications such as hematoma and extraintestinal fistula. ePTFE is less likely to produce adhesions when in contact with organs, but is less resistant to infection than polypropylene mesh. A composite patch (Composix E/X patch) is a combination of polypropylene mesh and ePTFE that combines the advantages of both. One side of the composite patch is woven with monofilament polypropylene, which stimulates tissue growth into the patch and effectively reduces the risk of recurrence; the other side is an expanded PTFE layer that extends into the abdominal cavity and prevents adhesions between the patch and vital organs in the abdominal cavity. After years of clinical treatment experience in our department, we believe that for huge incisional hernias with large abdominal wall defects that are difficult to close and must be repaired intraperitoneally, composite patch is a more ideal material for repair, which has less or no separation of abdominal wall tissues, easier placement of patch, less formation of hematoma or plasma swelling after surgery, less complications, faster postoperative recovery, lower recurrence rate, and better efficacy. However, in clinical practice, the type of repair to be used should be decided according to the specific situation of each patient to find the best repair solution. 3.6 Postoperative management Postoperative management of incisional hernia repair is also an important part of ensuring the success of surgery. We believe that prophylactic application of antibiotics can significantly reduce the incidence of abdominal surgical incisional hernia infection, especially for patients of advanced age, diabetes mellitus, immunocompromised, huge or multiple recurrent incisional hernias, repair with large biomaterials and incisions that may suffer from gastrointestinal bacterial contamination. Postoperative antibiotic application can be adjusted according to experience and bacteriological monitoring indicators, usually 48 hours after surgery. Postoperatively, the closed drainage should be ensured to be airtight and the drainage should be unobstructed. The removal of the drainage tube needs to be based on the drainage flow, and the drainage tube can be removed if the drainage flow is less than 20 ml. Postoperatively, the abdomen should be wrapped with a lap band for more than 3 months to ensure complete healing of the incision. Patients can be active in bed in the early postoperative period and can get out of bed after 2-3 days to prevent the occurrence of intestinal obstruction, but strenuous activities and heavy physical labor are prohibited for 3 months after surgery. Patients with incisional hernia have a slow recovery of intestinal function due to the placement of a larger mesh in the abdominal cavity. Most patients will develop abdominal distension and individual patients will develop inflammatory bowel obstruction, which can be treated with infrared light and acupuncture as early as possible to promote recovery of intestinal function. Although surgical treatment of incisional hernia has made significant progress, there are still risks such as patch-related infections, so a cautious attitude should be taken for some high-risk patients, and adequate preoperative, intraoperative and postoperative preparations should be made to avoid postoperative complications such as infection and abdominal hiatus syndrome.