Complex abdominal wall hernia refers to giant hernias and/or abdominal wall hernias complicated by a series of comorbidities. Among these, infection is a major factor contributing to the failure of abdominal wall hernia repair surgery. Abdominal wall hernia complicated by infection mainly includes the following categories: (1) Abdominal wall hernia complicated by skin and soft tissue infection; (2) Abdominal wall hernia complicated by occult abdominal wall or intra-abdominal infection; (3) Abdominal wall hernia complicated by mesh infection; (4) Complex conditions resulting from abdominal wall hernia complicated by mesh infection (e.g., organ erosion, massive defect after debridement and resection). Improper management of abdominal wall hernia with infection can lead to re-infection or hernia recurrence, necessitating multiple surgical interventions. This not only increases costs for patients and healthcare insurance but also severely impacts patients’ quality of life and trust in physicians [1]. The treatment philosophy for such patients differs significantly from routine abdominal wall hernia repair, posing a challenge for hernia surgeons. Therefore, it is essential to rigorously evaluate the infection preoperatively and intraoperatively, carefully determine the surgical timing, select appropriate surgical methods, and strengthen perioperative management. Furthermore, there is controversy regarding whether to adopt staged treatment (first-stage debridement and mesh removal, second-stage repair and reconstruction) or single-stage repair. Currently, there is no unified understanding of the clinical diagnosis and treatment of abdominal wall hernia complicated by infection, and there is a lack of relevant guidelines and consensus. Clinical management mostly follows individualized principles.

This consensus is formed based on the latest research and perspectives on abdominal wall hernia complicated by infection, and after repeated discussions among experts of the editorial committee, aiming to provide some reference for clinical diagnosis and treatment.

I. Abdominal wall hernia complicated by skin and soft tissue infection

Abdominal wall hernia complicated by skin or soft tissue infection is not uncommon clinically. Etiological investigations of abdominal wall hernia have found that patients with abdominal wall infection and poor incision healing following appendectomy or cholecystectomy, which subsequently lead to incisional hernia, account for over 40% of patients with incisional hernia [2]. These patients often present with incisional hernia along with local skin and soft tissue infection. Additionally, giant abdominal wall hernia with a long history can be complicated by chronic skin ulcers. The presence of the primary infection focus makes the placement of hernia repair materials challenging. If the infection involves the repair material, it can cause deep abdominal wall infection, leading to more severe consequences. For patients with abdominal wall hernia complicated by skin or soft tissue infection, according to the “Guidelines for Diagnosis and Treatment of Abdominal Incisional Hernia (2018 Edition)” by the Hernia and Abdominal Wall Surgery Group of the Chinese Medical Association, the principle is to perform debridement and anti-infection treatment first, followed by clinical observation (≥3 months) after complete healing of the abdominal wall infection, and then elective hernia repair surgery [3]. However, this treatment approach increases the economic burden on patients and significantly prolongs the treatment cycle.

In recent years, some experts have proposed the concept of single-stage surgery for abdominal wall hernia complicated by skin or soft tissue infection [4]. For patients with localized infection or large superficial ulcers, after necessary preoperative preparation, the principles of abdominal wall hernia management can be followed, performing simultaneous removal of the infection focus, repair and reconstruction of the abdominal wall defect, and skin plastic surgery (excision of the skin ulcer). Strict aseptic technique should be maintained intraoperatively, and drains should be placed appropriately. Postoperative antibiotic therapy based on bacterial culture results can control infection, with a low risk of re-infection.

II. Abdominal wall hernia complicated by occult infection

Abdominal wall hernia complicated by occult abdominal wall or intra-abdominal infection also falls under the category of abdominal wall hernia with skin and soft tissue infection. However, its clinical symptoms and signs are more insidious and difficult to detect preoperatively, testing the clinician’s treatment experience and attention to surgical details. The ability to detect the occult infection focus intraoperatively is one of the key factors determining the success or failure of the repair. Such patients often have a history of previous surgery complicated by intra-abdominal infection, especially gastrointestinal fistula. Their clinical characteristics include: (1) Long disease duration (months to years) without obvious local skin or soft tissue infection foci; (2) Preoperative ultrasound and CT examinations show no detectable abscess besides the abdominal wall defect; (3) Rough soft tissue dissection during surgery without paying attention to potential occult infection foci within the soft tissue, leading to wound contamination and infection spread. These occult infection foci often harbor broad-spectrum drug-resistant bacteria, making it difficult for the surgeon to decide on the choice of hernia repair material and placement method.

Therefore, the key to managing such patients with abdominal wall hernia is: Preoperatively, fully understand the history of intra-abdominal infection or gastrointestinal fistula; operate carefully intraoperatively to promptly detect and completely remove the infection foci (including occult sinuses, encapsulated abscesses, infected suture knots, and surrounding necrotic tissue); wipe or soak the area locally with iodophor to avoid contamination of the surgical field; place closed drains; send infected material for bacterial culture; and use postoperative antibiotics appropriately.

III. Abdominal wall hernia complicated by mesh infection

(I) Etiological factors of mesh infection in abdominal wall hernia

Abdominal wall hernia complicated by mesh-related infection is defined as infectious events directly or indirectly related to the mesh after mesh implantation. Based on the timing of infection, it is divided into early infection (postoperative < 30 days) and late-onset infection (postoperative ≥ 30 days). It often manifests as acute inflammation near the surgical incision, followed by signs of local fluid collection, persistent skin breakdown, pus discharge, chronic sinus tract formation, and even partial mesh exposure [5]. Furthermore, mesh erosion into organs can lead to a series of severe complications such as intestinal obstruction, abdominopelvic abscess, enterocutaneous fistula, and urinary fistula [6-7].

The main causes of mesh infection can be summarized as follows: (1) Patient factors. Smoking, obesity, comorbidities such as immunodeficiency, malnutrition, hypoalbuminemia, diabetes mellitus, use of hormones, immunosuppressants, etc. [8]. (2) Iatrogenic factors. Including strict adherence to aseptic principles, the technical skill of the operator, and rational use of antibiotics for early intervention when risk factors for postoperative infection exist [9]. (3) Mesh material factors. The material, type, placement layer, and method of fascia release are significantly correlated with the occurrence of mesh infection. Clinical observations have found that ordinary mesh plugs, microporous flat sheets, and materials containing expanded polytetrafluoroethylene (ePTFE) have a higher incidence of mesh-related infection [10-17].

(II) Diagnosis and evaluation of abdominal wall hernia complicated by mesh infection

The diagnosis of mesh infection is primarily based on a comprehensive assessment of the patient’s history, physical examination, and ancillary test results. However, for complex mesh infections such as mesh erosion into intra-abdominal organs, diagnosis is often more difficult and requires richer clinical experience.

1. History: The patient has a history of the following prodromal symptoms after mesh repair surgery, such as local skin redness, subcutaneous fluid accumulation, poor wound healing, fever, or a history of long-term recurrent infection and partial mesh removal.

2. Physical examination: Formation of one or more sinuses in the abdominal wall, with discharge of pus, intestinal fluid, urine, or feces from the sinuses, or accompanied by partial intestinal obstruction.

3. Ancillary tests: Clinically, imaging studies such as abdominal ultrasound, CT, and MRI, as well as blood tests and secretion cultures, are often used to diagnose mesh-related infection. The advantage of ultrasound is its ability to dynamically observe the morphology and position of the mesh and local fluid collection, determine the extent of infection, and, combined with ultrasound-guided puncture and aspiration, make treatment more precise [18-19]. Sinogram combined with CT scan can help assess deep mesh infection or organ erosion [20-21]. Studies have shown that the diagnostic value of ultrasound combined with CT is superior to that of ultrasound or CT alone. Secretion cultures can guide perioperative antibiotic use. Routine blood tests include C-reactive protein and white blood cell count [22-23].

(III) Surgical management of abdominal wall hernia complicated by mesh infection

1. Management of surgical site infection after abdominal wall hernia surgery: Surgical site infection (SSI) after abdominal wall hernia surgery is one of the direct causes leading to subsequent mesh-related infection. Strict intraoperative aseptic technique, irrigation of the surgical field with iodophor, and placement of negative-pressure drainage can reduce the occurrence of SSI. If SSI occurs, it requires careful and timely management. Clinically, SSI is divided into superficial and deep infections. Superficial incisional infections are not significantly different from routine soft tissue infections; most patients recover after interventions such as dressing changes, drainage, and additional antimicrobial agents. Deep infections, however, are more likely to involve the mesh. Even after interventions such as dressing changes, debridement, and negative-pressure suction, there remains a risk of non-healing wounds and mesh infection [24].

2. Mesh salvage measures: Not all patients with mesh infection require mesh removal. Some patients can undergo mesh salvage measures to successfully retain the mesh and avoid reoperation [25-26]. The success rate of conservative treatment also varies significantly depending on the mesh type and placement layer. Furthermore, cases where conservative treatment is more successful are more likely to be written and published. Such literature reports are mostly short-term studies lacking long-term follow-up to assess mesh re-infection. Therefore, the success rate of conservative treatment is likely to be significantly overestimated.

Measures for mesh salvage include: (1) Targeted antibiotic therapy; (2) Active dressing changes at the incision site; (3) For abscess formation meeting puncture indications, puncture and drainage can be performed; (4) Continuous negative-pressure suction. The above measures can effectively control milder mesh infections, offering a chance to retain the mesh.

3. Indications for mesh removal: These include (1) Infections caused by ordinary mesh plugs, microporous flat sheets, or composite materials containing ePTFE require mesh removal [17,27]; (2) Imaging studies such as ultrasound or CT show severe mesh shrinkage and deformation, with infection foci or abscesses surrounded by dense fibrous tissue; (3) Confirmed mesh erosion into organs, such as the intestine, bladder, or blood vessels; (4) Failure of active mesh salvage measures, poor granulation growth after 1-2 weeks of treatment with complete or partial mesh retention, or recurrent infection [7]; (5) Mesh infection involving methicillin-resistant Staphylococcus aureus (MRSA); (6) Significant distress to the patient’s life, physical and mental health, with the patient firmly requesting mesh removal.

4. Surgical timing: For early postoperative infection after abdominal wall hernia surgery, some patients’ wounds may heal with conservative treatment [25-26], requiring close follow-up thereafter. Conservative treatment measures have limited efficacy for chronic mesh infection or sinus tract formation, necessitating surgical removal of the infected mesh. In the early stage of infection, the mesh has not fully integrated with the tissue; removal is easier, and the incidence of postoperative complications is lower, but the hernia recurrence rate is higher. For chronic infection, due to granulation tissue ingrowth into the mesh and significant scar hyperplasia in the surgical area, some patients have dense intestinal adhesions or organ erosion, making surgery significantly more difficult and increasing related complications. Most studies suggest that conservative treatment generally should not exceed 6 months [24-25, 28-29]. However, there is no unified opinion on when to stop, so the optimal surgical timing for mesh infection remains controversial. Regarding staged surgery, literature published after 2012 supports short-interval second-stage repair: the first stage involves lysis of adhesions, mesh removal, resection of diseased bowel, partial hernia sac resection, abdominal lavage, and attempting to close the abdominal wall. If closure is impossible, a Bogota bag is used for temporary abdominal closure. After 5-8 days of postoperative nutritional support and antibiotic therapy, the second-stage repair is performed [30].

5. Key surgical points:

(1) Intraoperative use of methylene blue. Methylene blue-guided mesh removal has certain application value. Injecting methylene blue through the sinus tract can help trace the mesh position and understand the infection layer, aiding in determining the presence of multi-space infection and organ erosion intraoperatively [31-32]. Using methylene blue tracing, the sinus tract and necrotic tissue are excised to completely remove the infection focus. Layer-by-layer dissection adequately exposes the mesh, allowing for operation as close to the mesh as possible, and careful removal of sutures fixing the mesh [33]. Generally, only the stained mesh is removed, leaving the unstained portion that is well-incorporated with the tissue. This can reduce both re-infection and hernia recurrence risk [4,31].

(2) Choice between complete and partial mesh removal. Complete versus partial mesh removal affects postoperative hernia recurrence and re-infection rates. There is still disagreement on how to choose. It is generally believed that partial mesh removal can achieve the dual purpose of controlling infection and using the retained mesh to reinforce the abdominal wall defect. A study from a multicenter hernia database analyzed clinical data of 1904 patients with abdominal wall hernia who underwent mesh removal, observing postoperative complications including SSI and reoperation rates. The results suggested that complications were significantly higher with partial mesh removal than with complete removal (35% vs. 29%, P=0.01) [34].

Some authors performed a systematic review and cohort meta-analysis comparing complete versus partial removal of infected mesh in abdominal wall hernia over the past 20 years, including 5 observational studies with a total of 421 patients. The results showed an infection recurrence rate of 58.5% for partial removal and 25.5% for complete removal, a statistically significant difference (P < 0.001). The hernia recurrence rate was 9.7% (8/82) for partial removal and 40.2% (41/102) for complete removal, but the difference was not statistically significant (P=0.15) [31]. Currently, for infections caused by ordinary mesh plugs, microporous flat sheets, or composite materials containing ePTFE, there is a consistent consensus favoring complete mesh removal.

(3) Postoperative complications and preventive measures. Mesh removal surgery may be associated with the following complications: ① Wound infection. Incisions for mesh infection are often Class III, with a high chance of postoperative incisional infection and subcutaneous abscess formation. Some studies suggest that half of the patients undergoing partial mesh removal experience recurrent infection and sinus tract formation [35-36]. Intraoperatively, attempt to remove as much mesh as possible, thoroughly debride necrotic tissue and dead space, and use targeted antibiotics based on bacterial culture results. ② Hernia recurrence. After removal of the infected mesh, the defect is often larger than the original defect. Repair and reconstruction are more difficult, the risk of hernia recurrence is high, and reoperation is challenging. Studies have shown that the recurrence rate is 88% with direct suture, 50%-90% with primary synthetic mesh, 14%-17% with primary biologic or biosynthetic mesh, and 35% with primary autologous tissue [37]. Given this, patient education should be strengthened. Postoperative use of an abdominal binder for at least 6 months, avoidance of heavy lifting, weight control, and regular follow-up are recommended. ③ Enterocutaneous fistula. Patients undergoing bowel repair or resection for bowel injury should be vigilant for postoperative enterocutaneous fistula. If diagnosed, immediate surgery is required. The reoperation method should consider factors such as mesh placement layer and whether to remove the mesh. Laparoscopic exploration and repair of intestinal perforation is a better option when conditions permit. Therefore, adequate bowel preparation should be performed before mesh removal surgery. Intraoperative careful manipulation reduces collateral damage and avoids abdominal contamination. For bowel anastomosis, ensure good blood supply to the anastomosis and perform necessary reinforcement. Postoperative rational use of antibiotics and nutritional support, placement of abdominal drains maintaining patency to prevent tube dislodgement.

6. Laparoscopic application: Laparoscopic surgery has been widely used in the repair of external abdominal hernias. Laparoscopic exploration in mesh infection surgery helps understand the extent of bowel adhesions, the presence of intra-abdominal abscesses, and organ erosion [38]. Even if open surgery is determined, laparoscopic exploration is still helpful. In recent years, some scholars have studied the efficacy of laparoscopic surgery for mesh infection after abdominal wall hernia repair, believing that laparoscopic removal of infected mesh placed via intraperitoneal onlay mesh (IPOM) offers advantages such as a high complete mesh removal rate, low infection recurrence rate, few collateral injuries, and rapid postoperative recovery, worthy of clinical application and promotion [8]. However, as this is a contaminated surgery, laparoscopic manipulation carries the potential for intra-abdominal contamination. Further studies are needed to evaluate its value in treating mesh-related infections.

6. Management of special intraoperative situations:

(1) Management of bowel adhesions and mesh erosion into organs. Due to the mesh material, placement layer, or fixation issues in the previous hernia repair surgery, the mesh can migrate and come into contact with the intestine or bladder, leading to erosion. This is particularly true for patients with preoperative bacterial cultures indicating Escherichia coli. As E. coli is a normal flora of the intestine, its translocation, along with persistent deep infection and direct contact stimulation from the mesh, makes enterocutaneous fistula highly likely [5]. For patients with suspected enterocutaneous or vesicocutaneous fistula preoperatively, ultrasound and CT should be completed first, along with sinogram, gastrointestinal or urinary tract imaging (or cystoscopy) to confirm the diagnosis. For patients with unclear preoperative findings but high suspicion of mesh erosion, intraoperative laparoscopy can be used to explore and confirm organ involvement. For patients with suspected or confirmed enterocutaneous fistula, adequate bowel preparation is necessary preoperatively. Intraoperatively, scissors should be used as much as possible for dissection, avoiding direct separation of dense adhesions with electrocautery or ultrasonic shears to reduce delayed bowel injury. If seromuscular injury of the bowel is found intraoperatively, it can be directly sutured and repaired. If there is mucosal damage or enterocutaneous fistula, primary segmental bowel resection and anastomosis can be performed. For patients with vesicocutaneous fistula, partial cystectomy is required, and an indwelling urinary catheter is placed postoperatively.

(2) Defect repair and abdominal wall reconstruction. After removal of the infected mesh, the integrity and tension of the abdominal wall are compromised. Simultaneously, excision of necrotic tissue further exacerbates the abdominal wall defect, potentially leading to an inability to repair a massive defect. For small to medium abdominal wall defects, direct suture repair is feasible. Monofilament non-absorbable sutures are recommended to maintain long-term tension and strength of the incision while reducing foreign body reaction to suture knots and microabscess formation around knots, thereby lowering the risk of SSI and hernia recurrence. For patients with preoperative assessment of a large abdominal wall defect, adequate preoperative preparation and necessary abdominal wall component separation or active volume reduction should be performed to reduce the defect area as much as possible intraoperatively. In non-severely contaminated situations, monofilament macroporous polypropylene mesh can be used for reinforcement repair, with drains placed in the surgical area. Biologic meshes have certain advantages in tolerating infection. However, contaminated surgical wounds may accelerate the degradation of biologic meshes, increasing the risk of hernia recurrence. Currently, there are many types of biologic meshes, and the surgeon should choose appropriately based on their properties. For massive defects where the fascial edges cannot be approximated, a “bridge” technique using mesh or autologous tissue can be employed for reconstruction and repair. Mesh reinforcement repair is suitable for Grade 1 (low risk) and Grade 2 (comorbidities) abdominal wall defects and some mildly contaminated Grade 3 (potentially contaminated) defects. It is not recommended for severely contaminated Grade 3 defects and Grade 4 (infected) defects. Temporary closure methods with second-stage repair can be used [39].

IV. Summary

The diagnosis and treatment of abdominal wall hernia complicated by skin/soft tissue or mesh infection are challenging. Improper management can lead to hernia repair failure, increase doctor-patient conflict, and burden healthcare insurance. Abdominal wall hernia with infection requires a long perioperative preparation period, complex surgery, and is prone to missing occult infection foci. Some patients may require staged surgery for repair. This consensus suggests: (1) For abdominal wall hernia with skin and soft tissue infection, when conditions permit, simultaneous removal of the infection focus, repair and reconstruction of the abdominal wall defect, and skin plastic surgery can be performed. For patients with a history of intra-abdominal infection, especially gastrointestinal fistula, vigilance for occult infection is necessary. Intraoperatively, careful manipulation and complete removal of infection foci (including occult sinuses, encapsulated small abscesses, infected suture knots, and surrounding necrotic tissue) should be performed to avoid contamination of the surgical field. Timely local wiping or soaking with iodophor, placement of closed drains, sending infected material for bacterial culture, and rational postoperative antibiotic use are recommended. (2) For abdominal wall hernia with mesh infection, detailed preoperative evaluation is required to decide on mesh salvage, partial or complete removal. Intraoperative use of methylene blue to locate the lesion, irrigation of the surgical field with iodophor, placement of negative-pressure drainage, and postoperative anti-infection treatment are key to successful surgery. (3) For organ erosion caused by mesh, such as enterocutaneous or vesicocutaneous fistula, and massive defects after removal of infected mesh, individualized treatment plans based on the specific intraoperative situation are necessary. The above treatment approaches are beneficial for improving the success rate of such abdominal wall hernia surgeries.