# Ventral and Incisional Hernia Repair

## Overview

Incisional hernias occur in 10 to 20% of patients after abdominal surgery, rising to 30 to 50% in high-risk populations including those with obesity, wound infection, and emergency surgery. Ventral hernia repair is one of the most commonly performed general surgery operations. Optimal outcomes depend on patient optimization, appropriate mesh selection and placement plane, and familiarity with component separation techniques for complex abdominal wall reconstruction.

## Classification

The European Hernia Society (EHS) classification categorizes ventral hernias by **location** (midline or lateral, with subclassification by anatomic zone), **width** (W1 for defects less than 4 cm, W2 for 4 to 10 cm, W3 for greater than 10 cm), and **recurrence** status (primary versus recurrent). Types include primary ventral hernias (epigastric, umbilical, Spigelian), incisional hernias (through a prior surgical incision), and parastomal hernias (around a stoma site).

## Risk Factors for Incisional Hernia Development

Surgical factors include midline incision (which carries the highest risk), emergency surgery, wound infection, fascial closure technique (running is preferred over interrupted), suture material (slowly absorbable is preferred), and an inadequate suture-to-wound length ratio below 4:1. Patient factors include obesity (BMI above 30), diabetes, smoking, malnutrition, immunosuppression, corticosteroid use, connective tissue disorders (Ehlers-Danlos, Marfan syndrome), chronic cough, and ascites.

### Prevention: Small Bites Technique

The STITCH trial demonstrated that fascial closure with small bites (5 mm from the edge, 5 mm apart) using a slowly absorbable suture (PDS or MonoPlus) with a suture-to-wound length ratio of 4:1 or greater reduced the incisional hernia rate from 21% to 13% at one year.

## Preoperative Optimization

Optimal outcomes require thorough preoperative preparation. Smoking cessation should be achieved a minimum of 4 weeks preoperatively (ideally 8 weeks). Weight loss should target a BMI below 35 to 40 before elective repair. Diabetes control should aim for an HbA1c below 8%. Nutritional optimization targets include albumin above 3.0 g/dL and prealbumin above 15 mg/dL. CT imaging is essential for operative planning, determining defect size, location, loss of domain, and component anatomy. For large hernias with loss of domain, **botulinum toxin injection** provides chemical component separation by relaxing the lateral abdominal wall muscles and is administered 4 to 6 weeks before surgery. **Progressive pneumoperitoneum**, involving serial insufflation of air into the peritoneal cavity over 1 to 3 weeks, expands the abdominal domain for massive hernias.

## Mesh Placement Planes

| Mesh Plane | Position | Advantages | Disadvantages | Recurrence |
|-----------|----------|-----------|---------------|------------|
| Onlay | Anterior to anterior rectus sheath | Technically simplest | Highest wound complications, highest recurrence | Highest |
| Sublay/Retrorectus (Rives-Stoppa) | Posterior to rectus, anterior to posterior sheath | Best integration, protected by muscle, lowest recurrence | Requires more dissection | Lowest (3–5%) |
| Preperitoneal (TAR) | Between peritoneum and transversus abdominis | Vast mesh coverage, extends lateral to rectus | More complex dissection | Low |
| Intraperitoneal (IPOM) | Within peritoneal cavity | Minimally invasive, rapid recovery | Adhesion risk, erosion risk, requires barrier-coated mesh | Higher than retrorectus |

**Onlay** mesh is placed anterior to the rectus sheath. While technically the simplest approach, it carries the highest wound complication rate (seroma, infection) and the highest recurrence rate, making it generally not preferred for incisional hernia repair.

**Sublay/retrorectus (Rives-Stoppa)** mesh is placed posterior to the rectus muscles but anterior to the posterior rectus sheath. This plane offers strong fixation, excellent mesh-tissue integration, protection by well-vascularized muscle (which resists infection), and the lowest recurrence rate. It is the **preferred plane** for midline incisional hernias based on current evidence.

**Preperitoneal** mesh, used in extended retrorectus or transversus abdominis release (TAR), is placed between the peritoneum and transversus abdominis muscle, allowing larger mesh coverage beyond the lateral edge of the rectus in continuity with the retrorectus space.

**Intraperitoneal (underlay/IPOM)** mesh is placed within the peritoneal cavity and must use barrier-coated mesh (ePTFE or composite) to prevent adhesion to bowel. This approach is used in laparoscopic ventral hernia repair. While it offers minimally invasive advantages and rapid recovery, it carries risks of adhesion, mesh erosion into bowel (rare but catastrophic), and higher recurrence than retrorectus placement.

## Open Repair Techniques

### Primary Suture Repair

Primary suture repair without mesh is acceptable only for very small defects (less than 2 cm) in healthy patients. The recurrence rate of 30 to 50% without mesh makes this approach generally not recommended for incisional hernias.

### Rives-Stoppa Retrorectus Repair

The Rives-Stoppa repair is the standard open approach for midline incisional hernias. Through a midline incision with excision of the old scar, the anterior rectus sheath is opened bilaterally, and the retrorectus space is developed by separating the rectus muscle from the posterior sheath. The posterior sheath (peritoneal layer) is closed in the midline. A large polypropylene mesh is placed in the retrorectus space, extending from the xiphoid to the pubis for large hernias and laterally to the linea semilunaris. The anterior rectus sheath is then closed over the mesh in the midline. This approach achieves a recurrence rate of 3 to 5%.

### Component Separation Techniques

#### Anterior Component Separation (Ramirez)

The anterior component separation involves release of the external oblique aponeurosis 1 to 2 cm lateral to the linea semilunaris, allowing medial advancement of the rectus-internal oblique-transversus abdominis complex. The advancement gained is 3 to 5 cm per side at the epigastrium, 7 to 10 cm per side at the umbilicus, and 1 to 3 cm per side at the suprapubic region. The original technique requires raising large subcutaneous flaps, which carries a higher wound complication rate. The endoscopic or perforator-sparing modification releases the external oblique without subcutaneous flaps, preserving periumbilical perforators and reducing wound complications.

#### Posterior Component Separation (Transversus Abdominis Release -- TAR)

The TAR involves division of the transversus abdominis muscle posterior to the rectus, allowing entry into the preperitoneal plane for wide mesh placement. This approach requires no subcutaneous flaps, preserves blood supply to the skin, provides vast mesh coverage area, and has a lower wound complication rate than anterior component separation. Combined with retrorectus mesh placement (extended Rives-Stoppa/TAR), this technique is increasingly preferred over anterior component separation for complex hernias.

## Minimally Invasive Approaches

**Laparoscopic IPOM** places barrier-coated mesh intraperitoneally with a minimum 3 to 5 cm overlap and fixation using tacks and/or transfascial sutures. It offers fewer wound complications and shorter hospital stay but carries risks of adhesion, chronic pain from fixation devices, and higher recurrence than retrorectus repair for larger defects.

**Robotic retrorectus repair (rTAR)** uses robotic transabdominal access to the retrorectus space, combining the benefits of minimally invasive surgery with retrorectus mesh placement. Growing evidence supports comparable outcomes to open Rives-Stoppa/TAR, though cost and operative time are higher.

The **eTEP (extended totally extraperitoneal)** approach uses a laparoscopic or robotic approach to the retrorectus space without entering the peritoneal cavity, similar to inguinal TEP but extended for ventral hernias.

## Mesh Selection

### Synthetic Mesh

**Polypropylene** is the most commonly used synthetic mesh material. Lightweight or medium-weight formulations are preferred over heavyweight for reduced stiffness and better compliance. **Polyester (Parietex)** offers good incorporation but may have higher infection and shrinkage rates. **ePTFE (Gore-Tex)** produces minimal adhesion to bowel but poor tissue incorporation and higher infection and recurrence rates if infected. **Composite mesh** has one side for tissue integration (polypropylene) and one side with a barrier coating for bowel contact, used for IPOM placement.

### Biologic Mesh

Biologic mesh is derived from human (AlloDerm), porcine (Strattice, Permacol), or bovine (SurgiMend) tissue and consists of decellularized extracellular matrix designed for tissue remodeling. It is intended for contaminated or infected fields. However, long-term recurrence rates are variable and often high (30 to 80% in some series), and evidence does not clearly support biologic over synthetic mesh even in contaminated fields.

### Biosynthetic Mesh

Biosynthetic (absorbable synthetic) mesh options include GORE BIO-A, Phasix (poly-4-hydroxybutyrate), and TIGR. These are slowly absorbed over 12 to 18 months while tissue remodels and are intended for contaminated or potentially contaminated fields. Emerging evidence suggests they may bridge the gap between synthetic and biologic mesh.

## Complications

The most common complication is **seroma**, a fluid collection in the hernia sac space that is usually self-limited. **Surgical site infection** occurs in 5 to 10% and is higher with onlay mesh, obesity, and diabetes. **Mesh infection** may require partial or complete explantation for synthetic mesh, while biologic mesh may be salvaged with drainage and antibiotics. **Recurrence** ranges from 5 to 15% depending on technique and mesh placement. **Chronic pain** may result from mesh, nerve entrapment, or tack fixation. **Bowel adhesion, obstruction, or fistula** is a risk with intraperitoneal mesh. **Skin necrosis** can result from extensive subcutaneous dissection during anterior component separation.

<image>Cross-sectional illustration of the abdominal wall showing the four potential mesh placement planes: onlay (anterior to the anterior rectus sheath), sublay/retrorectus (between the rectus muscle and posterior rectus sheath), preperitoneal (between the posterior rectus sheath/transversalis fascia and peritoneum), and intraperitoneal underlay (IPOM, on the peritoneal surface). Label each layer of the abdominal wall (skin, subcutaneous fat, anterior rectus sheath, rectus muscle, posterior rectus sheath, transversalis fascia, peritoneum) and show the mesh position in each plane.</image>

<image>Surgical illustration of the posterior component separation (transversus abdominis release - TAR) technique showing: (1) the retrorectus space developed bilaterally, (2) identification and division of the transversus abdominis muscle medial to the neurovascular bundles, (3) entry into the preperitoneal space, and (4) large mesh placement extending from the retrorectus space laterally into the preperitoneal space. Show the final cross-sectional view with mesh coverage and fascial closure.</image>

<image>Diagram showing the medial advancement gained by anterior component separation (Ramirez technique) at three levels: 3-5 cm per side at the epigastrium, 7-10 cm per side at the umbilicus, and 1-3 cm per side at the suprapubic region. Show the external oblique release site (1-2 cm lateral to the linea semilunaris) and the direction of medial advancement of the composite flap (rectus + internal oblique + transversus abdominis).</image>

## Clinical Pearls

The retrorectus (Rives-Stoppa) plane is the preferred mesh position for midline incisional hernia repair, offering the best combination of tissue integration and low recurrence. Fascial closure with small bites (5 mm from edge, 5 mm apart) and a suture-to-wound length ratio of 4:1 or greater reduces incisional hernia formation as demonstrated by the STITCH trial. Component separation should be performed only when the fascia cannot be closed primarily after full retrorectus dissection. Posterior component separation (TAR) is increasingly preferred over anterior component separation due to lower wound complication rates and broader mesh coverage. Biologic mesh has not been proven superior to synthetic mesh even in contaminated fields, and biosynthetic mesh is emerging as a reasonable alternative. Preoperative optimization including smoking cessation, weight loss, diabetes control, and nutritional repletion is critical for reducing surgical site complications and recurrence. Intraperitoneal mesh (IPOM) requires a barrier-coated surface to prevent bowel adhesion -- uncoated polypropylene must never be placed against bowel. Preoperative botulinum toxin injection to the lateral abdominal wall muscles can provide chemical component separation and facilitate closure of large defects.

## References

- Breuing K, Butler CE, Ferzoco S, et al. Incisional ventral hernias: review of the literature and recommendations regarding the grading and technique of repair. *Surgery*. 2010;148(3):544-558.
- Deerenberg TC, Harlaar JJ, Steyerberg EW, et al. Small bites versus large bites for closure of abdominal midline incisions (STITCH): a double-blind, multicentre, randomised controlled trial. *Lancet*. 2015;386(10000):1254-1260.
- Holihan JL, Nguyen DH, Nguyen MT, et al. Mesh location in open ventral hernia repair: a systematic review and network meta-analysis. *World J Surg*. 2016;40(1):89-99.
- Novitsky YW, Elliott HL, Orenstein SB, Rosen MJ. Transversus abdominis muscle release: a novel approach to posterior component separation during complex abdominal wall reconstruction. *Am J Surg*. 2012;204(5):709-716.