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🏥 Abdominal Wall & Ventral Hernia — Masterclass

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1. ANATOMY OF THE ABDOMINAL WALL

Layers (Surface to Deep)

1. Skin
2. Subcutaneous tissue (Camper's & Scarpa's fascia)
3. External oblique muscle/aponeurosis - fibers run inferomedially
4. Internal oblique muscle - fibers run superomedially (perpendicular to external oblique)
5. Transversus abdominis muscle (TA) - fibers run transversely
6. Transversalis fascia
7. Preperitoneal fat
8. Peritoneum

Key Structures

Neurovascular Supply

• Segmental nerves T7-T12 and L1 (iliohypogastric, ilioinguinal) run between the internal oblique and TA in the neurovascular plane
• Large perforating neurovascular bundles at the linea semilunaris define the lateral boundary of safe retrorectus dissection

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2. DEFINITION & EPIDEMIOLOGY

• Primary hernias - occur at inherent anatomic weak points (umbilical, epigastric, Spigelian)
• Incisional hernias - result from failure of a prior surgical wound
• Traumatic hernias - rare, from blunt force

• ~350,000 ventral hernia repairs/year in the USA
• ~500,000 inguinal hernia repairs/year in the USA
• Incisional hernia occurs in 2-30% of laparotomies
• Total procedural costs exceed $3.2 billion/year in the USA - and that does not count complication management

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3. CLASSIFICATION

EHS (European Hernia Society) Midline Classification (Muysoms et al., Hernia 2009)

Ventral Hernia Working Group (VHWG) Grade - for mesh selection

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4. TYPES OF PRIMARY VENTRAL HERNIAS

Umbilical Hernia

• Defect within 3 cm superior or inferior to the umbilicus (EHS definition)
• Adults: acquired, due to gradual weakening of the linea alba around the umbilical ring
• Risk factors: obesity, multiple pregnancies, cirrhosis (ascites), COPD, connective tissue disorders
• In infants: usually close spontaneously by age 2-3; repair if persists beyond age 4-5

Epigastric Hernia

• Located >3 cm below xiphoid and >3 cm above umbilicus
• May be multiple and lateral to midline
• Often contain preperitoneal fat (falciform ligament) ± peritoneal sac
• Mechanism: weakness at vascular bundle penetration points through linea alba

Spigelian Hernia

• Incidence: 0.12-2.4% of all abdominal wall hernias
• At the lateral border of rectus muscle / medial edge of linea semilunaris
• Usually an intraparietal (interparietal) hernia - external oblique remains intact; hernia passes through TA and internal oblique only
• Most common below the arcuate line
• Often occult on examination; diagnosed by ultrasound or CT
• CT finding: hernia sac at lateral border of rectus in characteristic crescent sign

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5. INCISIONAL HERNIA

Risk Factors

Prevention

• The STITCH trial approach: small bites (0.5 cm × 0.5 cm) with a 4:1 suture-to-wound length ratio using slowly absorbable suture (PDS/Maxon) minimizes incisional hernia risk
• Prophylactic mesh placement at index laparotomy in high-risk patients is increasingly practiced

Pathophysiology of Recurrence

• Suture-only incisional hernia repair: 43% recurrence at 2 years, 63% at 10 years
• Mesh-based repair: 24% recurrence at 2 years, 32% at 10 years (Luijendijk et al.)

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6. PREOPERATIVE WORKUP & OPTIMIZATION

Clinical Assessment

• History: onset, duration, change in size, reducibility, prior repairs, comorbidities
• Exam: size, reducibility, skin changes, overlying scarring, abdominal domain assessment
• Loss of domain (LOD): when hernia contents can no longer be safely reduced without respiratory compromise; identified by CT volumetry (hernia volume >20-25% of total abdominal volume)

Imaging

• CT with hernia protocol (supine ± Valsalva): standard for complex hernias
  • Assess defect size and number
  • Identify contents (bowel, omentum, solid organ)
  • Evaluate loss of domain
  • Detect incarceration/strangulation
• Ultrasound: for small, clinically ambiguous hernias (especially Spigelian)

Patient Optimization (mandatory before elective repair)

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7. SURGICAL PRINCIPLES: MESH

Why Mesh? (Evidence)

• Umbilical hernias <4 cm: mesh reduces recurrence (4% vs. 12%, HR 0.31); effect is present even for 1-2 cm defects
• EHS/AHS guidelines: mesh for defects >1 cm (EHS) or >2 cm (many centers)
• Optimal patients for suture-only primary repair: defect <1 cm AND BMI <30

Mesh Categories

• Net meshes (PP, POL): allow tissue ingrowth between strands; become integrated into host within months
• Sheet meshes (ePTFE): do not allow tissue ingrowth; become encapsulated
• Inlay mesh (edge-to-edge) is NEVER acceptable - extremely high recurrence; condemned

• Dual-sided: parietal (PP/POL) side promotes integration; visceral side has anti-adhesive barrier (absorbable coating, titanium, etc.)
• Required for intraperitoneal placement (IPOM) to prevent bowel adhesions, fistulae, erosion

• Combines tensile strength of synthetic with improved biocompatibility
• Slow degradation profiles preferred (fast degradation → high recurrence)
• After resorption, associated tissues retain mechanical strength
• Used in contaminated fields (clean-contaminated, contaminated)

• Derived from human/bovine/porcine tissue; scaffold for tissue regeneration
• Designed for infected/contaminated fields (VHWG Grade 3-4)
• EXPENSIVE; recurrence ~30% at 2 years in contaminated fields
• Intense foreign-body reaction, poor tissue integration in contaminated environments
• No FDA clearance for contaminated wounds; biologic mesh has not outperformed synthetic in randomized trials
• Reserve for grossly contaminated fields or last resort

• Pushed into small defects; produces "meshoma" - fibrous mass causing chronic pain
• Complications: mesh migration, erosion into adjacent organs, fistula
• Largely abandoned

Mesh Position Options

• Onlay and sublay: minimum 3-5 cm in all directions
• Open retrorectus/TAR: minimum 5 cm overlap with bare polypropylene
• Fixation-free repair is feasible with sufficient overlap in defects ≤15 cm (Etemad et al.)

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8. OPERATIVE APPROACHES: OPEN

Open Primary Repair (suture-only)

• Figure-of-eight or interrupted transverse closure
• Slowly absorbable monofilament (PDS) or permanent suture
• Permanent suture risk: foreign body sensation, suture granulomas - some surgeons avoid it
• Key: fascial healing takes >1 year; suture must last through the proliferative phase

Open Onlay Mesh Repair

• Fascial closure first, then mesh on top of anterior fascia
• Large subcutaneous flaps increase SSO/SSI risk - major drawback

Open Preperitoneal Repair (Umbilical/Epigastric)

• Curvilinear incision; dissect down to hernia sac
• Preserve hernia sac to facilitate preperitoneal plane entry
• Dissect preperitoneal pocket circumferentially: overlap of 3-5 cm
• Close peritoneal holes with absorbable suture; lay flat sheet of PP or hernia patch
• Intra-abdominal pressure holds mesh - fixation sutures often not needed
• Then close fascia over mesh with permanent or slowly absorbable suture

Open Intraperitoneal Repair (Hernia Patch)

• For thin peritoneum where preperitoneal pocket creation is risky
• Hernia sac transected at fascial level; contents reduced
• Barrier-coated patch placed intraperitoneally, fixed with sutures ± positioning tails/memory rings
• Fascia closed over top

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9. MYOFASCIAL RELEASE TECHNIQUES (Component Separation)

A. External Oblique Release (Anterior Component Separation, ACS)

1. Create skin and subcutaneous flaps over anterior rectus sheath, lateral to rectus muscle
2. Incise posterior rectus sheath just lateral to linea alba; separate rectus from posterior sheath
3. Incise external oblique aponeurosis just lateral to linea semilunaris, from costal margin to iliac crest
4. Separate external oblique from anterior lamella of internal oblique
5. Close midline fascia

B. Retrorectus Repair (Rives-Stoppa)

• Posterior rectus sheath incised just lateral to linea alba (bilateral)
• Rectus muscle separated from posterior sheath (retrorectus space)
• Wide mesh placed in this space, well vascularized, protected from bowel
• Lateral extent: linea semilunaris (neurovascular perforators)
• Inferiorly: below arcuate line, connect both sides; can extend into Space of Retzius to Cooper's ligaments
• Posterior sheath closed over mesh with 2-0 resorbable suture; anterior fascia then closed

C. Transversus Abdominis Release (TAR) - Posterior Component Separation (PCS)

1. At the linea semilunaris, the medial leaf of the posterior TA fascia is incised
2. This releases the TA muscle, expanding the preperitoneal plane laterally beyond the linea semilunaris
3. The plane is extended between the TA muscle anteriorly and the preperitoneal fat/peritoneum posteriorly
4. Bilateral TAR opens a vast retromuscular/preperitoneal space for very large mesh placement

• Posterior component separation (TAR) provides greater myofascial advancement than anterior (ACS), especially in the upper and mid abdomen
• No skin flaps required → dramatically lower SSO/SSI and skin necrosis rates
• Preferred for complex abdominal wall reconstruction with large defects

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10. MINIMALLY INVASIVE APPROACHES

Laparoscopic Ventral Hernia Repair (LVHR)

• 3-5 ports lateral to the hernia
• Complete adhesiolysis
• Hernia contents reduced
• Barrier-coated mesh placed intraperitoneally with adequate overlap (≥5 cm)
• Mesh fixated: transfascial sutures at corners + tacks/staples circumferentially

• Requires intraperitoneal (barrier-coated) mesh → long-term adhesion/fistula risk
• Difficulty closing fascial defect (bulge persists even with reduced hernia)
• Challenging in patients with prior adhesions, multiple hernias, loss of domain

Robotic Ventral Hernia Repair

• Access retrorectus space via retroperitoneal ports
• Bilateral retrorectus dissection under robotic magnification
• Posterior sheath closed (barbed 2-0 slowly absorbable suture)
• Fascial defect closed with No.1 barbed suture (pulley technique at 10-12 mmHg)
• Bare polypropylene mesh placed in retrorectus pocket - no barrier needed
• Minimum 5 cm overlap in all directions

• If posterior sheath cannot close without undue tension → TAR must be considered
• Inability to close posterior sheath without tension → indication to convert to open
• Closing posterior sheath under tension → breakdown → intraparietal hernias
• Fixation: interrupted 3-0 absorbable suture or fibrin sealant; minimal fixation typically needed

• Extension of robotic retrorectus dissection
• Medial leaf of posterior TA fascia incised at linea semilunaris to expand preperitoneal plane laterally
• Enables repair of very large defects minimally invasively

• Enhanced 3D visualization
• Articulating instruments - superior ergonomics
• Enables intracorporeal suturing (defect closure, posterior sheath closure)
• Facilitates extraperitoneal mesh placement (no barrier mesh needed)

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11. SPECIAL HERNIAS

Parastomal Hernia

• Hernia adjacent to a stoma site (ileostomy or colostomy)
• Incidence: 24-86% of stoma patients at some point
• EHS Classification: Small (<5 cm) vs. Large (>5 cm) ± presence of stoma prolapse
• Management: conservative (hernia belt), stoma relocation, repair with mesh (Sugarbaker technique, keyhole technique, modified Sugarbaker)

Lumbar (Flank) Hernia

• Superior lumbar triangle (Grynfeltt): bounded by 12th rib, internal oblique, erector spinae - more common
• Inferior lumbar triangle (Petit): bounded by iliac crest, external oblique, latissimus dorsi
• Can be primary (acquired/congenital) or secondary (post-incisional)
• Often contain retroperitoneal fat; bowel herniation less common

Spigelian Hernia

• Location: lateral edge of rectus / medial edge of linea semilunaris, below arcuate line
• Intraparietal - external oblique intact; diagnosis missed on clinical exam
• CT or ultrasound required for diagnosis
• Repair: open or laparoscopic; mesh placement recommended

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12. COMPLICATIONS OF HERNIA REPAIR

Surgical Site Events (SSE)

Long-term Complications

Complications Specific to Minimally Invasive Repair

• Inability to tolerate pneumoperitoneum
• Trocar-site hernia
• Bowel injury during adhesiolysis (especially from thermal energy near hernia sac - electrosurgery must be used cautiously)

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13. PERIOPERATIVE MANAGEMENT

Analgesia (Enhanced Recovery Protocol)

• Epidural analgesia for open hernia repair: large NSQIP/ACHQC database studies show increased LOS, increased complications (UTI, PE), and increased transfusion with no improvement in pain control - NOT recommended
• Preferred approach: TAP (transversus abdominis plane) blocks intraoperatively + preoperative "cocktail":
  • Acetaminophen 1,000 mg
  • Pregabalin 75 mg
  • Celecoxib 400 mg
• This multimodal approach reduces LOS and opioid use

Abdominal Binder

• A 2024 systematic review/meta-analysis (PMID 39550494) found that abdominal binders after ventral hernia repair reduce seroma formation and improve patient comfort

Smoking

• A 2024 meta-analysis on smoking and hernia repair (PMID 39085514) confirmed smoking significantly increases complications and recurrence after both ventral and inguinal hernia repair - cessation is mandatory before elective repair

Local Anesthesia

• A 2025 systematic review (PMID 40420065) confirmed feasibility and safety of ventral hernia repairs under local anesthesia in selected patients

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14. DECISION-MAKING FRAMEWORK

VENTRAL HERNIA IDENTIFIED
         |
         ├── Asymptomatic, very small (<1 cm), low-risk patient
         │         → Watch and wait (discuss risks/benefits with patient)
         │
         ├── Symptomatic OR enlarging OR incarcerated/strangulated
         │         → Surgical repair indicated
         │
         └── OPERATIVE PLANNING:
              │
              ├── Optimize: BMI, smoking, DM, nutrition
              │
              ├── Defect size?
              │    ├── <1 cm + BMI<30 → Primary suture repair acceptable
              │    ├── 1-4 cm → Mesh (preperitoneal or IPOM-Plus)
              │    └── >4 cm → Mesh + consider component separation
              │
              ├── Contamination grade? (VHWG)
              │    ├── Grade 1-2: permanent synthetic mesh
              │    ├── Grade 3: biosynthetic preferred; caution with synthetic
              │    └── Grade 4: biologic (last resort) OR damage-control bridging
              │
              ├── Loss of domain?
              │    └── Yes → Progressive pneumoperitoneum preoperatively
              │
              └── Approach?
                   ├── Small/medium, laparoscopic-suitable → Robotic/laparoscopic (eTEP or IPOM-Plus)
                   ├── Large midline, complex → Open retrorectus ± TAR
                   └── Contaminated/emergency → Open ± bridging mesh

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15. QUICK-REFERENCE HIGH-YIELD FACTS

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• Fischer's Mastery of Surgery, 8th ed., Chapters 216-217
• Sabiston Textbook of Surgery, Chapter 80
• Bailey and Love's Short Practice of Surgery, 28th ed., Chapter 64
• Current Surgical Therapy, 14th ed., Chapters 5, 10
• Mulholland & Greenfield's Surgery, 7th ed., Chapters 72-73

1. Emergency triage - incarceration/strangulation branches off immediately to emergency repair
2. Preoperative optimization - the five key targets (BMI, smoking, HbA1c, albumin, infection)
3. Loss of domain assessment - triggers progressive pneumoperitoneum if present
4. Contamination grading (VHWG) - drives mesh type selection (synthetic → biosynthetic → biologic)
5. Defect size decision - routes to primary repair, laparoscopic/robotic eTEP or IPOM-Plus, or open retrorectus ± component separation
6. TAR vs ACS annotation - highlights TAR's superiority for complex reconstruction
7. Mesh position reference table - onlay, retrorectus, preperitoneal, IPOM at a glance
8. Bottom key rules bar - critical numbers and condemned techniques at a glance