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Groin Hernias: Direct Inguinal, Indirect Inguinal & Femoral

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1. ANATOMY OF THE INGUINAL REGION (Foundation)

Inguinal Canal

• Deep (internal) inguinal ring: Defect in transversalis fascia, midway between ASIS and pubic tubercle, ~2–3 cm above and lateral to the femoral artery pulse. The inferior epigastric vessels run just medial to this ring — this is the single most important anatomical landmark for distinguishing hernia types.
• Superficial (external) inguinal ring: Inverted-V defect in the external oblique aponeurosis, just superolateral to the pubic tubercle.

Canal Contents

• Males: Spermatic cord (testicular artery, pampiniform plexus veins, vas deferens, lymphatics) + cremasteric muscle
• Females: Round ligament
• Both sexes: Ilioinguinal nerve, iliohypogastric nerve, genital branch of genitofemoral nerve

Hesselbach's Triangle (Direct Hernia Space)

Femoral Canal

• Anterosuperior: Inguinal ligament
• Lateral: Femoral vein
• Medial: Lacunar (Gimbernat's) ligament — sharp, unyielding edge
• Posteroinferior: Pubic bone + pectineus covered by iliopectineal (Astley Cooper's) ligament

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2. INDIRECT INGUINAL HERNIA

Definition

Aetiology / Pathogenesis

• Congenital (most cases in children): Failure of the processus vaginalis to obliterate after testicular descent. The processus is a finger-like peritoneal projection that accompanies the testis into the scrotum. Normally obliterates before birth — explains high incidence in premature infants.
• Acquired (adults): Persistent patency or stretching of the deep inguinal ring under chronic positive intra-abdominal pressure; risk factors include heavy lifting, chronic cough, constipation, BPH, ascites.
• All congenital inguinal hernias are, by definition, indirect.

Epidemiology

• Most common hernia overall
• M:F ratio ~10:1
• More common on the right side (delayed obliteration of processus vaginalis on right due to later testicular descent)
• Highest incidence in infants and young men; can occur at any age

Anatomy of the Hernia Sac

• Sac passes within the spermatic cord through the entire inguinal canal
• Can enter the scrotum — forming a scrotal (complete) hernia or inguinoscrotal hernia
• Sac lies anteromedial to the spermatic cord
• Neck of sac is at the deep inguinal ring, lateral to the inferior epigastric vessels

Types by Contents

• Enterocele: Contains intestine (resonant on percussion)
• Epiplocele: Contains omentum (dull on percussion)
• Sliding hernia: Retroperitoneal structure (caecum on right, sigmoid on left) forms part of the sac wall itself — sac formed secondarily

Complications

1. Irreducibility: Contents cannot be returned to abdominal cavity
2. Obstruction: Intestinal obstruction without vascular compromise
3. Strangulation: Vascular compromise → ischaemia/gangrene. More common in indirect (narrow neck) than direct hernia
4. Inflammation / infection: Rare; hernia mimics acute abdomen

Clinical Features

• Symptoms: Groin swelling appearing on standing/straining; aching discomfort; reducible with lying down
• Swelling location: Above and medial to the pubic tubercle (inguinal hernias in general); passes into scrotum in complete hernia
• Cough impulse: Expansile impulse on coughing
• Reducibility: Reduces on lying + gentle pressure with thigh flexed/internally rotated
• Cannot get above it: In complete hernia, examiner cannot insinuate fingers above the swelling at the groin

Examination — Key Test: Deep Ring Occlusion Test

• Indirect hernia: Hernia does not appear (controlled by ring occlusion)
• Direct hernia: Hernia bulges medially (passes through Hesselbach's triangle, not the ring)

Invagination Test

• Impulse felt at the fingertip = indirect hernia (coming down the canal)
• Impulse against the side of the finger = direct hernia (pushing through posterior wall)

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3. DIRECT INGUINAL HERNIA

Definition

Aetiology / Pathogenesis

• Always acquired — never congenital
• Results from progressive weakening and stretching of the transversalis fascia in Hesselbach's triangle
• Risk factors: Elderly age (most characteristic), obesity, chronic straining (constipation, COPD, prostatic outflow obstruction), connective tissue disorders, previous surgery
• The area is inherently weak because there is no muscle reinforcement — only transversalis fascia + external oblique aponeurosis

Epidemiology

• Predominantly in elderly males
• Less common than indirect overall; in elderly men, may approach similar frequency to indirect
• Rarely seen in women or children
• Bilateral in up to 20% of cases

Anatomy of the Hernia Sac

• Does not pass through the deep inguinal ring
• Does not enter the scrotum (usually — may do so if very large)
• Broad-based neck → low risk of strangulation (most important distinguishing feature from indirect)
• Bladder may be dragged into a large direct hernia (medial portion of sac wall)

Clinical Features

• Usually a diffuse, broad-based bulge in the medial groin
• Reduces spontaneously on lying down; reappears on standing
• Less likely to be a complete scrotal hernia
• Lower complication risk than indirect hernia

Pantaloon Hernia

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4. COMPARISON: DIRECT vs. INDIRECT INGUINAL HERNIA

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5. FEMORAL HERNIA

Definition

Epidemiology

• F:M ratio ~2:1 overall for femoral hernias — but even in women, inguinal hernia is still commoner than femoral in the groin
• Rare before age 20; incidence rises with age; peak over 50
• Right side twice as common as left; 20% bilateral
• Thin, elderly women are classically at highest risk (wider female pelvis enlarges femoral canal)

Pathogenesis

• The female pelvis is wider → femoral canal is larger → greater predisposition
• Weight loss or ageing further enlarges the femoral defect
• The neck is rigid and unyielding (lacunar ligament medially, femoral vein laterally) → extremely prone to strangulation
• ~50% of femoral hernias present as emergencies with strangulation

Shape — The "Retort" Sign

• While within the narrow femoral canal, the hernia is small
• Once through the saphenous opening into loose areolar tissue, it expands, then turns upward above the inguinal ligament → characteristic retort/flask shape
• This upward reflection can cause confusion with an inguinal hernia

Boundaries of the Femoral Canal

Clinical Features

• Swelling: Small, globular; below and lateral to the pubic tubercle; below the inguinal ligament
• Often only 1–2 cm and easily missed or mistaken for a lymph node
• Cough impulse may be absent due to tightness of the neck
• Rapidly becomes irreducible
• Symptoms less pronounced than inguinal hernia early on

Key Distinguishing Points from Inguinal Hernia

Differential Diagnosis of Femoral Hernia

1. Enlarged inguinal lymph node (most common mimic — look for infection focus in drainage area: perineum, lower limb, anal canal)
2. Saphena varix (disappears completely lying down; fluid thrill on coughing; positive Schwartz's test; associated varicose veins)
3. Femoral artery aneurysm (pulsatile, expansile)
4. Psoas abscess (cold abscess from Pott's disease; lateral to femoral vessels; fluctuant)
5. Lipoma of cord
6. Node of Cloquet enlargement within femoral canal
7. Rupture/haematoma of adductor longus

Pre-vascular Femoral Hernia (Rare)

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6. SURGICAL MANAGEMENT

Inguinal Hernia

A. Open Suture Repairs (Tension)

• Bassini repair (1890): Opens external oblique aponeurosis; separates cord; reduces sac; sutures conjoint tendon to inguinal ligament from pubic tubercle to deep ring. Historical gold standard.
• Shouldice repair: Transversalis fascia opened and double-breasted (two-layer closure) + external oblique similarly. Lifetime recurrence <2% at expert centres. Technically demanding.
• Desarda repair: Strip of external oblique aponeurosis sutured to conjoint tendon and inguinal ligament as a dynamic reinforcement. Considered equivalent to Shouldice.
• Maloney darn: Continuous non-absorbable suture (nylon/polypropylene) between conjoint tendon and inguinal ligament. Most common where mesh is unavailable.

B. Open Flat Mesh Repair (Tension-free)

• Lichtenstein repair (1980s onwards): Prosthetic polypropylene mesh laid flat over the posterior wall and sutured to inguinal ligament + conjoint tendon. A slit in the mesh accommodates the cord. Recurrence <1%. Current standard for open repair in most settings.
• Mesh plug (Rutkow-Robbins): Cone-shaped mesh plug placed into the deep ring ± flat mesh overlay.

C. Laparoscopic / Minimally Invasive Repair

• TAPP (Trans-Abdominal Pre-Peritoneal): Laparoscopic access into peritoneum; mesh placed in preperitoneal space via intra-abdominal approach.
• TEP (Totally Extra-Peritoneal): Balloon dissection of preperitoneal space; peritoneum never entered. Preferred by many.
• Advantages: Bilateral hernia repair through same port sites; faster recovery; less chronic pain; excellent for recurrent hernia after open repair.
• Requires general anaesthesia; higher cost; longer learning curve.

Classification (European Hernia Society)

• P (primary) or R (recurrent)
• L (lateral/indirect), M (medial/direct), F (femoral)
• Defect size in fingerbreadths (1 = ≤1.5 cm, 2 = 1.5–4.5 cm, 3 = ≥4.5 cm)
• Example: Primary indirect inguinal hernia with 3-cm defect = PL2

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Femoral Hernia — "No Alternative to Surgery; Treat Urgently"

1. Low Approach — Lockwood

• Simplest; suitable when bowel resection is NOT anticipated
• Can be done under local anaesthesia
• Transverse incision over the hernia below the inguinal ligament
• Sac opened and contents reduced; sac reduced; sutures placed between inguinal ligament above and pectineal (Cooper's) ligament below
• Medial lacunar ligament may be incised to aid reduction (caution: abnormal obturator artery branch may bleed)
• Femoral vein protected at all times

2. Inguinal Approach — Lotheissen

• Same incision as Lichtenstein; enters inguinal canal
• Transversalis fascia opened from deep ring to pubic tubercle → entry into extraperitoneal space
• Hernia lies immediately below; reduced by pulling from above + pushing from below
• Neck closed with sutures/mesh plug; flat mesh laid in extraperitoneal plane
• Allows simultaneous repair of coexisting inguinal hernia

3. High Approach — McEvedy

• Preferred when bowel resection may be necessary (strangulation)
• Vertical or oblique incision above inguinal ligament; enters extraperitoneal space from above
• Best access to the sac contents; allows opening of peritoneum if needed
• Obturator approach possible via same incision

4. Laparoscopic (TAPP/TEP)

• Appropriate for elective uncomplicated femoral hernias
• Mesh placed in preperitoneal space covering the myopectineal orifice (femoral, direct, and indirect spaces)
• Advantage: Simultaneous identification and repair of all three defect types

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7. COMPLICATIONS OF HERNIA (All Types)

Strangulation Risk by Type

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8. DIAGNOSTIC AIDS

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9. QUICK SUMMARY TABLE

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