Hernia & Abdominal Wall

Definition

A hernia is the protrusion of a viscus or part of a viscus through a normal or abnormal opening in the walls of its containing cavity. An inguinal hernia is protrusion of abdominal contents through the inguinal canal.

Classification

Inguinal Canal — Boundaries (Exam Essential)

Hesselbach’s Triangle

The direct hernia zone — bounded by:

• Medial: Lateral border of rectus abdominis
• Lateral: Inferior epigastric vessels (IEV)
• Inferior: Inguinal ligament

Contents: Site of direct inguinal hernia (weakness of transversalis fascia). Mesh must fully cover this area in all repairs.

Myopectineal Orifice of Fruchaud (MPO)

The single anatomical weak area through which all groin hernias (direct, indirect, femoral) occur. Bounded by: lateral — femoral canal; medial — rectus sheath; inferior — Cooper’s (pectineal) ligament. The single mesh in laparoscopic repair covers the entire MPO — this is why TAPP/TEP repairs have lower recurrence than open anatomical repairs.

Layers of the Abdominal Wall (Medial to Lateral at Groin)

Skin → Camper’s fascia → Scarpa’s fascia → External oblique aponeurosis → Internal oblique → Transversus abdominis → Transversalis fascia → Preperitoneal fat → Peritoneum.

Definition

The Myopectineal Orifice (MPO) of Fruchaud is the single weak area in the lower abdominal wall through which all groin hernias (inguinal — direct and indirect; femoral) originate. It is the anatomical basis for the laparoscopic philosophy of placing a single large mesh to cover the entire orifice.

Boundaries

Contents / Hernia Sites Within the MPO

Surgical Significance — Why MPO Matters

• A single prosthetic mesh placed in the preperitoneal plane covering the entire MPO eliminates all three potential hernia sites simultaneously → this is the core principle of TAPP and TEP repair
• Open anatomical repairs (Lichtenstein, Bassini) only address the specific defect; mesh must be positioned to overlap the pubic tubercle medially and cover beyond the internal ring laterally to approximate MPO coverage
• Mesh size in laparoscopic repair (10 × 15 cm or larger) is designed to reliably cover the entire MPO with ≥3–4 cm overlap on all sides
• The MPO concept explains why femoral hernias must be covered by laparoscopic mesh placed below Cooper’s ligament — the femoral canal is part of the MPO

Iliopubic Tract

The iliopubic tract is a thickened band of transversalis fascia running parallel to, and deep to, the inguinal ligament. It is the key inferior landmark for mesh fixation in laparoscopic repair:

• Tacks placed above the iliopubic tract (medially to Cooper’s, superiorly to rectus) = safe fixation zones
• Tacks placed below or lateral to the iliopubic tract = triangle of pain = nerve injury → chronic groin pain

Definition

Femoral hernia is the protrusion of abdominal contents through the femoral canal, below and medial to the femoral vessels, below the inguinal ligament.

Femoral Canal — Boundaries

• Medial: Lacunar ligament (Gimbernat’s ligament)
• Lateral: Femoral vein
• Anterior: Inguinal ligament
• Posterior: Cooper’s (pectineal) ligament and pectineus fascia

Key Features

• More common in women (wider pelvis → wider femoral canal)
• However, overall inguinal hernia is still more common in women than femoral hernia
• High risk of strangulation due to narrow, rigid neck (bounded by unyielding ligaments)
• Presents as a swelling below and lateral to pubic tubercle (vs inguinal hernia: above and medial to pubic tubercle)

Repair Options

Definition

An irreducible hernia in which the blood supply of the contents (bowel/omentum) is compromised, leading to ischaemia, necrosis, and risk of perforation and peritonitis.

Sequence of Events

Clinical Features

Local: Tense, tender, irreducible swelling; no cough impulse; skin erythema and warmth.

Systemic: Persistent pain (not colicky); features of intestinal obstruction (colicky pain, vomiting, distension, absolute constipation); rebound tenderness; shock and toxaemia in advanced cases.

Management

1. Resuscitation:

   IV access; IV fluids (crystalloids); IV antibiotics (broad-spectrum); nasogastric tube and urinary catheter; correct electrolyte imbalance
2. Emergency surgery — no delay:

   Do not attempt taxis (forcible reduction) in strangulation — risks reducing gangrenous bowel into abdomen
3. Intraoperative assessment:

   Open hernia sac; assess viability of contents (colour, peristalsis, pulsations in mesentery)
4. If bowel viable:

   Reduce contents; repair hernia (Lichtenstein if clean field or simple repair in contaminated field)
5. If bowel gangrenous:

   Resect bowel segment; primary anastomosis (if clean) or stoma; avoid mesh in contaminated field

Viability Assessment of Bowel

Viable: Pink/red colour; active peristalsis present; arterial pulsations in mesentery; shiny serosal surface.

Non-viable (gangrenous): Black/green/purple discoloration; no peristalsis; no mesenteric pulsation; flaccid, dull surface → must be resected.

Three Landmark Triangles

Preperitoneal Spaces (TEP Anatomy)

• Space of Retzius (Retropubic space, medial): Between pubic symphysis/bladder and transversalis fascia. Dissected first in TEP. Exposes Cooper’s ligament and pubic symphysis medially.
• Bogros’ space (lateral): Between transversalis fascia and peritoneum, lateral to IEV. Extends toward ASIS. Allows lateral mesh coverage over indirect defects.
• Arcuate line (Douglas’ line): Posterior rectus sheath ends ~4–5 cm below umbilicus. Below this, only transversalis fascia covers the rectus. TEP balloon expansion is easier below this line.

Vascular Hazards in Laparoscopic Hernia Repair

• Corona mortis: Anomalous vascular anastomosis between obturator vessels and external iliac/inferior epigastric vessels, coursing over the superior pubic ramus. Variable presence (~30%). Injury during Cooper’s ligament dissection causes difficult-to-control haemorrhage. Always look for it — clip/ligate if seen.
• IEV injury: From blind lateral dissection in TEP
• Deep circumflex iliac vein: Near lateral Cooper’s ligament dissection

Spermatic Cord Contents (Laparoscopic View)

• Vas deferens (medial, thick, white)
• Testicular (gonadal) vessels (lateral, thin)
• Pampiniform plexus (venous)
• Cremasteric vessels; genital branch of genitofemoral nerve

Principle

A tension-free, open anterior mesh repair of inguinal hernia using a flat polypropylene mesh that reinforces the posterior wall of the inguinal canal and extends laterally to cover the deep inguinal ring. The “tension-free” concept (Lichtenstein, 1989) revolutionised hernia surgery by reducing recurrence rates to <1%.

Anaesthesia

Local anaesthesia (LA) preferred — reduces systemic risk, faster discharge, day-case surgery. LA: Xylocaine 2% (20 mL) + Bupivacaine 0.5% (10 mL) + Normal saline (50 mL) + Adrenaline (1:10,000) — injected layer by layer.

Operative Steps

1. Incision:

   Skin crease incision 1.25 cm above and parallel to the medial 2/3 of inguinal ligament
2. Dissection:

   Divide Camper’s and Scarpa’s fascia; identify and open external oblique aponeurosis through superficial ring; identify and protect 3 nerves (ilioinguinal, iliohypogastric, genital branch of genitofemoral)
3. Cord dissection:

   Lift spermatic cord on finger; identify indirect sac (anterolateral) → high dissection and ligation; push direct sac back (do not open unless obstructed); sliding hernia → reduce viscus, do not ligate sac fully
4. Mesh placement:

   Polypropylene mesh 6 × 11 cm (or 15 × 8 cm); place behind cord, covering posterior wall; first stitch medial edge 2 cm past pubic tubercle; inferior edge sutured to inguinal ligament with continuous suture (pubic tubercle to just lateral to deep ring); lateral end slit to create two tails around cord (“neo-ring” — must be loose)
5. Superior fixation:

   Upper edge of mesh sutured loosely to conjoint tendon / internal oblique with 2–3 interrupted sutures (“air-lock sutures” — not tight)
6. Closure:

   Replace cord with nerves; close external oblique aponeurosis over mesh; subcuticular skin closure

Key Fixation Points (Exam Table)

Complications

Early: Haematoma/seroma; urinary retention; wound infection; cord or vas injury.

Late:

• Chronic groin pain (inguinodynia): Neuropathic (nerve entrapment — ilioinguinal, iliohypogastric, genital branch) or mesh-related (meshoma, shrinkage). Manage stepwise: NSAIDs → neuropathic agents → nerve blocks → selective neurectomy and mesh release.
• Testicular complications: Ischaemic orchitis, testicular atrophy, hydrocele — from pampiniform plexus trauma or tight neo-ring.
• Mesh infection: Rare; antibiotics first; chronic infection → mesh explant.
• Recurrence: Due to inadequate medial overlap, missed femoral hernia, or infection. Overlap: ≥2 cm past pubic tubercle medially; 3–5 cm lateral to internal ring.

Port Placement

• 10 mm umbilical/supra-umbilical camera port
• Two 5 mm working ports in lower quadrants (midclavicular line, 2 cm above ASIS)
• Surgeon stands on opposite side to hernia; monitor at patient’s feet
• Trendelenburg 10–15°; pneumoperitoneum 12–15 mmHg

Stepwise Procedure

1. Diagnostic survey:

   Inspect both groins; identify hernia type (direct, indirect, femoral)
2. Peritoneal incision:

   Incise peritoneum 2–3 cm above deep ring, from medial umbilical ligament to ASIS; elevate superior peritoneal flap to expose preperitoneal space
3. Preperitoneal dissection:

   Identify IEV; Cooper’s ligament; vas deferens (medial) and gonadal vessels (lateral); dissect Space of Retzius medially and Bogros’ space laterally
4. Hernia sac dissection:

   Reduce sac completely; for indirect: dissect sac from cord structures; avoid triangle of doom and pain during dissection; for sliding hernia: reduce viscus carefully
5. Mesh placement:

   Insert 10 × 15 cm polypropylene or 3D mesh; cover direct, indirect, femoral and obturator orifices (entire MPO); fix mesh: tacks or glue to Cooper’s ligament medially and rectus sheath superiorly; NO fixation below iliopubic tract or in triangle of pain
6. Peritoneal closure:

   Close peritoneal flap with continuous absorbable suture (2-0 Vicryl) or tacks; mesh must be completely covered — prevents bowel adhesion to mesh
7. Port closure:

   Desufflate under vision; close 10 mm port fascia with absorbable suture

Port Placement

• 10 mm infra-umbilical port (camera) — extraperitoneal entry
• Two 5 mm midline ports: one midway umbilicus–pubic symphysis; one just above pubic arch
• All ports in extraperitoneal plane (NOT intraperitoneal)

Stepwise Procedure

1. Extraperitoneal access:

   Subumbilical incision; incise anterior rectus sheath; dissect preperitoneal space with balloon dissector (preferred) or blunt telescopic dissection; insufflate CO₂ 10–12 mmHg to expand extraperitoneal space
2. Landmark identification:

   Pubic symphysis and Cooper’s ligament medially; IEV superiorly; vas deferens (medial) and gonadal vessels (lateral); myopectineal orifice
3. Hernia sac dissection:

   Indirect: sac anterolateral to cord → dissect from cord, reduce preperitoneally; Direct: reduce transversalis fascia bulge; Femoral: dissect below Cooper’s ligament, reduce sac
4. Mesh placement:

   Insert 10 × 15 cm polypropylene or 3D mesh; cover entire MPO (direct, indirect, femoral, obturator); no fixation often adequate (intraperitoneal pressure holds mesh); if fixation: medial to Cooper’s ligament and superiorly to rectus sheath only; avoid fixation below iliopubic tract (triangle of pain)
5. Desufflation and port closure:

   Slowly desufflate while holding mesh flat; remove ports under vision; close 10 mm port fascia

TEP-Specific Complications

• Peritoneal tear: CO₂ escapes → loss of working space; manage with endoscopic suture repair or convert to TAPP
• Subcutaneous emphysema: CO₂ tracking into subcutaneous tissue; self-limiting
• IEV or external iliac injury: From blind lateral dissection

Material Classification

Weight Classification

Composite Mesh — Why Needed?

Plain polypropylene in direct contact with bowel causes dense adhesions, erosion, and fistula. Composite meshes have an anti-adhesion visceral layer (facing bowel) and a pro-ingrowth parietal layer (facing abdominal wall).

Common products: Proceed (PP + ORC + PDS), Parietex Composite (polyester + collagen film), DualMesh (ePTFE bilateral), Ventralight, Bard Sepramesh.

Definitions

Incisional hernia: Abdominal wall defect, with or without a bulge, in a postoperative scar — perceptible or palpable on clinical examination.

Ventral hernia: Protrusion of peritoneal contents through a spontaneous (non-incisional) defect in the abdominal wall (umbilical, paraumbilical, epigastric, spigelian).

Modern Paradigm

Anatomic fascial closure + large extraperitoneal mesh + minimise intraperitoneal mesh contact + risk-factor optimisation and prehabilitation.

Indications for Repair

• Symptomatic: pain, functional limitation, progressive enlargement
• Skin changes or risk of rupture/ulceration
• Intermittent incarceration or obstruction
• Cosmesis and core instability (selected patients)
• Failure of conservative management (binders, weight loss)

Contraindications (Relative)

• Active SSI / uncontrolled sepsis / contaminated field without staged strategy
• Unoptimised comorbidities (severe cardiopulmonary disease, uncontrolled diabetes, active smoking)
• Morbid obesity (weight reduction recommended before repair)
• Enterocutaneous fistula (avoid permanent synthetic mesh)

Mesh Position Options

Prehabilitation Adjuncts

• Botulinum toxin A (BTA): Chemical component separation — injected into lateral abdominal wall muscles 2–6 weeks pre-op; paralyses and lengthens lateral muscles, facilitating midline closure without permanent incision
• Progressive preoperative pneumoperitoneum (PPP): Serial CO₂ insufflation over days/weeks to stretch abdominal wall; used in major loss-of-domain cases
• ciNPWT (Closed-Incision NPWT): Reduces SSI on closed incisions in high-risk patients
• Prophylactic mesh: High-risk primary laparotomies (obese, malnourished) to prevent incisional hernia

European Hernia Society (EHS) Classification

Classification by Location and Size (width):

Example

A large umbilical hernia with a 12 cm defect = M3 W3. A subcostal post-cholecystectomy hernia 5 cm wide = L1 W2.

Definition

Loss of domain (LOD) hernia is a large abdominal wall defect in which the herniated viscera can no longer be safely returned to the peritoneal cavity without causing respiratory compromise, abdominal compartment syndrome, or inability to close the fascia.

Criteria for Loss of Domain

• Tanaka ratio ≥0.25: Hernia sac volume ÷ Total abdominal cavity volume ≥25% (measured on CT volumetry)
• Hernia defect >10 cm (W3) with inability to achieve midline closure
• Long-standing hernia with shortened and atrophied lateral abdominal wall muscles

Preoperative Preparation

1. Optimise comorbidities:

   Smoking cessation ≥4 weeks; glycaemic control; nutritional rehabilitation; weight loss
2. CT volumetry:

   Measure hernia sac and abdominal cavity volumes to calculate Tanaka ratio and plan repair
3. Progressive preoperative pneumoperitoneum (PPP):

   Serial CO₂ insufflation into peritoneal cavity (100–1000 mL/day over 2–3 weeks) via percutaneous catheter; stretches and re-acclimatises abdominal wall muscles and respiratory system
4. Botulinum toxin A (BTA):

   Injected into lateral abdominal wall (EO, IO, TA muscles) under CT guidance 2–6 weeks pre-op; chemical component separation; lengthens and relaxes lateral muscles facilitating midline closure
5. Anaesthetic assessment:

   Pulmonary function tests; ensure patient can tolerate increased intra-abdominal pressure after repair

Surgical Repair

• Almost always requires component separation (ACS or TAR) for tension-free fascial closure
• Large retromuscular mesh (TAR preferred — lower wound morbidity)
• Biological mesh if contaminated field
• ciNPWT on closed incision in high-risk cases

Concept

TAR = Posterior Component Separation. The posterior rectus sheath is incised medial to the neurovascular bundles, and the transversus abdominis muscle is divided. This creates a large retromuscular (Rives–Stoppa) space that allows massive mesh placement with minimal skin flaps.

Indications

• Large midline hernia (defect >8–10 cm, W3)
• Complex or recurrent incisional hernias
• Loss of domain
• When anterior tissues are weak, scarred, or when ACS is contraindicated
• Need for retromuscular mesh placement with minimal wound morbidity

Operative Steps

1. Midline exposure:

   Midline incision; excise scar; perform adhesiolysis; expose hernia sac
2. Retrorectus dissection (Rives–Stoppa):

   Incise posterior rectus sheath just medial to linea semilunaris; develop retrorectus space bilaterally (between rectus anteriorly and posterior sheath/transversalis fascia posteriorly) to the lateral border of rectus
3. Posterior sheath incision:

   Continue incision through the posterior rectus sheath at its lateral edge, medial to the neurovascular bundles entering the rectus
4. Transversus abdominis (TA) release:

   Divide the TA muscle in the retrorectus plane, medial to the neurovascular bundles; this is the “release” step — allows lateral advancement of rectus complex
5. Bilateral extension:

   Extend bilaterally; total advancement of 8–10 cm per side achievable
6. Posterior layer closure:

   Close posterior rectus sheath / peritoneum in midline (if possible) to create a closed retromuscular pocket for mesh
7. Mesh placement:

   Large retromuscular mesh (20 × 30 cm or larger); placed in the retromuscular space; 5–10 cm overlap on all sides
8. Anterior fascial closure:

   Close anterior rectus sheaths in midline without tension
9. Closure:

   Minimal skin flaps; drains in retromuscular space; ciNPWT on incision if high-risk

TAR vs ACS

Concept

In ACS (Ramirez, 1990), the external oblique (EO) aponeurosis is divided lateral to the linea semilunaris and separated from the internal oblique (IO). This allows the rectus + IO + TA complex to slide medially towards the midline, gaining 10–15 cm of advancement per side. Unlike TAR, ACS works anteriorly and requires large subcutaneous skin flaps → higher wound morbidity.

Indications

• Large midline ventral hernias (>10 cm, W3); loss of domain
• When posterior plane is unavailable (scarred, prior mesh) and TAR is not feasible
• Anterior tissues are healthy (no skin/flap necrosis risk)

Operative Steps

1. Midline exposure:

   Midline incision; raise subcutaneous flaps laterally to expose external oblique aponeurosis
2. External oblique release:

   Incise EO aponeurosis 1–2 cm lateral to the linea semilunaris; continue from costal margin to iliac crest
3. Separation:

   Undermine and separate EO from IO (the plane between them); allows rectus + IO complex to mobilise medially
4. Midline closure:

   Approximate anterior rectus sheaths in midline without tension
5. Mesh reinforcement:

   Onlay mesh above closed anterior rectus sheath (or sublay if Rives–Stoppa also performed)
6. Closure:

   Close subcutaneous flaps over drains; EO aponeurosis NOT closed (left open to maintain advancement)

Perforator-Sparing Modifications

• Perforator-sparing ACS: Avoid ligation of periumbilical perforators → preserves blood supply to skin flaps → reduces flap necrosis
• Endoscopic ACS (E-ACS): Endoscopic EO release through small ports, avoiding large skin incisions → reduces wound morbidity significantly

Advantages

• 10–15 cm advancement per side (slightly more than TAR in some studies)
• No entry into retroperitoneal plane (useful if posterior scarred)
• Well-established technique (original Ramirez 1990)

Disadvantages

• Large subcutaneous flap dissection → flap necrosis, wound dehiscence, seroma (main limitation)
• Sacrifice of periumbilical perforators → ischaemia in standard open ACS
• Higher SSI rate than TAR
• Mesh usually onlay (not retromuscular) → less durable position

Modern Philosophy of Ventral & Incisional Hernia Repair

The paradigm has shifted from intraperitoneal bridging repairs to anatomic fascial closure + large extraperitoneal mesh reinforcement + wound morbidity reduction. The goal is core restoration, not just defect coverage.

Complete Abbreviation Reference

Mesh Plane Quick Recall

Key Techniques in Detail

IPOM & IPOM-Plus

• IPOM: Laparoscopic; composite mesh placed intraperitoneally; fix with transfascial sutures ± tackers; for small–medium hernias (≤6 cm); avoid in contaminated field or ECF
• IPOM-Plus: Adds intracorporeal laparoscopic closure of fascial defect (barbed suture) before mesh placement → restores linea alba, reduces bulge and seroma, lower recurrence
• Hybrid IPOM: Small open incision for adhesiolysis/defect closure + laparoscopic mesh; for large defects (>10 cm)

TARUP (Laparoscopic Rives–Stoppa)

• Trans-abdominal laparoscopic access → posterior sheath incision → retromuscular space bilaterally → posterior sheaths re-approximated → large macroporous lightweight mesh in retromuscular sublay plane
• Essentially the laparoscopic Rives–Stoppa — durable, tension-free, minimal complications

TARM (Trans-Abdominal Retro-Muscular Repair)

• More extensive than TARUP; retromuscular space developed beyond linea semilunaris with partial TA division
• Indication: Larger (6–12 cm) or complex midline hernias after failed IPOM
• Robotic variant: r-TARM

eTEP-RS (Enhanced-view Totally Extraperitoneal — Retro-Rectus Sublay)

• Entry via lateral port to retro-rectus space; develop bilateral retro-rectus planes, cross midline; close defect under vision; insert large retromuscular mesh
• Advantage: Avoids peritoneal entry; low pain; early recovery
• Complication: Peritoneal breach → convert to TARM/TAPP

eTEP-TAR

• eTEP-RS + posterior sheath incision medial to linea semilunaris → divide transversus abdominis → gain 8–10 cm bilateral advancement
• Indication: Large or loss-of-domain midline hernias
• Mesh plane: Extended retromuscular

MILOS / EMILOS

• MILOS: 4–6 cm transhernial incision → endoscopic dissection of retromuscular space → posterior reconstruction + fascial closure → large mesh; combines open durability with minimal-access morbidity
• EMILOS: Evolution of MILOS — entire retromuscular dissection done endoscopically; smaller scars, earlier discharge

SCOLA (Subcutaneous Onlay Laparoscopic Approach)

• Subcutaneous working space via suprapubic ports; pre-peritoneal plane anterior to rectus; close defect and place mesh fixed to Cooper’s ligament
• Indication: Low midline or suprapubic hernias below arcuate line

ELAR (Endoscopic-Assisted Linea Alba Reconstruction)

• Small midline incision; plicate linea alba; onlay mesh reinforcement
• Indication: Epigastric hernia or rectus diastasis with small defects; excellent cosmesis

Complications by Mesh Plane

Hybrid and Novel Techniques (Mention-Worthy)

High-Yield Viva Pearls

• Gold standard mesh plane: Retromuscular sublay (Rives–Stoppa / eTEP / MILOS)
• Modern philosophy: Fascial closure + extraperitoneal large mesh + risk optimisation
• Posterior CS (TAR) replaces anterior CS for large defects — less wound morbidity
• Robotic AWR: Improves ergonomics, reduces LOS, similar recurrence to open
• Avoid bridging (inlay) repairs — highest recurrence rate
• ciNPWT on closed incisions lowers SSI rates in high-risk reconstructions
• Prophylactic mesh in high-risk primary laparotomies prevents incisional hernia (EHS 2023 recommendation)
• BTA + PPP together give best domain restoration before repair in LOD hernias