Inguinal Hernia 101

Definition & Epidemiology

Anatomy of the Inguinal Canal

• Inferior: Inguinal ligament
• Superolateral: Inferior epigastric artery
• Medial: Lateral edge of the rectus abdominis

Types of Inguinal Hernia

Indirect Inguinal Hernia

• Passes through the deep inguinal ring, lateral to the inferior epigastric vessels, then travels along the inguinal canal, exits via the superficial ring, and can descend into the scrotum (or labium majus)
• Most common hernia overall (~66% of all inguinal hernias)
• In children: caused by a patent processus vaginalis (failure of closure before birth) — all pediatric hernias are by definition indirect
• In adults: also occurs due to the persistent processus vaginalis or acquired weakness
• Higher risk of incarceration due to narrow neck at the deep ring

Direct Inguinal Hernia

• Passes directly through the posterior wall of the inguinal canal (Hesselbach's triangle), medial to the inferior epigastric vessels
• Does not travel down the inguinal canal
• Acquired weakness — caused by aging and repetitive stress from increased intra-abdominal pressure
• Typically has a wide neck → lower incarceration risk
• Common in older men

Reducibility Classification

Clinical Presentation

• Groin bulge — appears or enlarges with standing, coughing (Valsalva), or straining; reduces when lying flat
• Pain/discomfort — pressure, sharp, or referred pain to scrotum/testicle/inner thigh (from nerve compression)
• Sudden onset pain → concerning for incarceration or strangulation
• Children: parents notice bulge during diaper change; infants are at high risk for incarceration due to narrow ring

Examination

1. Inspect standing patient — look for bulge in groin/scrotum
2. Palpate — advance index finger through scrotum toward the external inguinal ring, ask patient to cough (Valsalva):
   • Impulse at the tip of finger → indirect hernia
   • Impulse on the dorsum of finger → direct hernia
   • (Note: clinical accuracy is only slightly better than chance — ~50%)
3. Inguinal occlusion test — block the deep ring with a finger; controlled impulse on cough = indirect (blocked), persistent bulge = direct
4. Femoral hernias: palpable below the inguinal ligament, lateral to the pubic tubercle

Imaging

Management

Watchful Waiting

• An option for asymptomatic/minimally symptomatic reducible inguinal hernias in adults, though morbidity is higher with emergency vs elective repair
• Not appropriate in children — spontaneous resolution does not occur; repair is always indicated once diagnosed

Surgical Repair — Key Principles

Open Anterior Approaches

Posterior/Preperitoneal Approaches

• Rives-Stoppa: Large mesh in preperitoneal space via infraumbilical incision; good for bilateral/recurrent hernias
• Open preperitoneal: Transverse incision above deep ring; enters preperitoneal space directly

Laparoscopic Approaches

• TEP (Totally Extraperitoneal) and TAPP (Transabdominal Preperitoneal)
• Mesh placed in the preperitoneal space covering the direct, indirect, and femoral spaces
• Key landmarks: Triangle of Doom (contains external iliac vessels — no fixation here), Triangle of Pain (contains genitofemoral nerve and lateral cutaneous nerve of the thigh)

Special Populations

Pediatric

• All pediatric hernias are indirect (patent processus vaginalis)
• Higher incidence in premature infants (closure of processus normally occurs months before birth)
• Incarceration occurs in 30% of hernias in children < 3 months
• If incarcerated but reducible → repair within 24–48 hours
• If unreducible or strangulated → emergency surgery
• In females: check for ovary in sac; rule out testicular feminization (androgen insensitivity)

Adults

• Females: rare inguinal hernias need to be distinguished from femoral hernias (higher strangulation risk)
• Obesity makes examination difficult and increases false-negative/false-positive rates
• Recurrent hernias: prefer preperitoneal mesh approach (Rives-Stoppa or laparoscopic) to avoid scarred anterior field

Complications of Repair

• Chronic groin pain (most common long-term complaint) — from nerve entrapment (ilioinguinal, iliohypogastric, genital branch of genitofemoral)
• Recurrence — lower with mesh (~1%) vs. tissue repair (~10–15%)
• Wound infection / mesh infection
• Injury to vas deferens or testicular vessels → infertility or testicular atrophy
• Hematoma / seroma

Intestinal Obstruction 101

Definition & Classification

Primary Classification

By Anatomical Location

Causes — A Surgical Framework

Common SBO Causes (in order of frequency)

• Adhesions (post-op) — #1, up to 75%
• Incarcerated hernia — #2
• Malignancy (carcinomatosis, direct invasion)
• Crohn's disease
• Volvulus / intussusception
• Gallstone ileus, radiation stricture, Meckel's

Common LBO Causes

• Colorectal carcinoma — #1
• Diverticulitis
• Volvulus (sigmoid > caecal)
• Metastatic disease
• Hernia (rare)

Pathophysiology

• Most gas = swallowed air + some intraluminal production
• Fluid = swallowed liquids + GI secretions (obstruction stimulates epithelial secretion)
• Bowel initially hyperactive → trying to overcome obstruction (accounts for colicky pain and paradoxical diarrhoea early on)
• Rising intraluminal pressure → impaired microvascular perfusion → ischaemia → necrosis (strangulation)
• Bacterial overgrowth and translocation occur; flora change from near-sterile to polymicrobial

Closed-Loop Obstruction

Partial vs. Complete

• Partial: some gas/fluid still passes; slower progression; strangulation less likely
• Complete: no passage; high risk of strangulation; requires more urgent intervention

Clinical Presentation

Classic tetrad:

1. Colicky abdominal pain — central (SBO) or lower (LBO)
2. Vomiting — early and frequent in proximal SBO; late/faeculent in distal SBO; late/absent in LBO
3. Distension — absent in proximal SBO; massive in distal/LBO
4. Absolute constipation / obstipation — complete obstruction; note that early on, some stool/flatus may still pass

Bowel Sounds

• Early mechanical obstruction: high-pitched, tinkling, frequent rushes
• Late / strangulation / ileus: diminished or absent

Signs of Strangulation (urgent surgical flag)

• Pain disproportionate to examination findings
• Tachycardia, fever
• Localised peritonism / guarding / rigidity
• Marked leukocytosis (>15–20 × 10⁹/L)
• Metabolic acidosis
• Irreducible tender mass (hernia context)

Diagnosis

Goals of diagnostic evaluation:

1. Distinguish mechanical obstruction from ileus
2. Determine SBO vs. LBO
3. Discriminate partial from complete
4. Detect strangulation or closed loop

Plain Abdominal Radiograph (AXR)

CT Abdomen/Pelvis (with oral contrast)

• Discrete transition zone — dilated proximal, collapsed distal
• Intraluminal contrast does not pass the transition point
• Colon contains little gas or fluid

• C-shaped or U-shaped dilated loop
• Radial distribution of mesenteric vessels converging toward a torsion point (whirl sign)

• Bowel wall thickening
• Pneumatosis intestinalis (air in bowel wall)
• Portal venous gas
• Mesenteric haziness/"fat stranding"
• Poor IV contrast enhancement of bowel wall

Water-Soluble Contrast (Gastrografin / Omnipaque)

• Appearance of contrast in the colon within 24 hours predicts non-operative resolution with sensitivity 92%, specificity 93%
• Has osmotic effect that may reduce oedema and promote resolution
• Preferred over barium if perforation suspected

Specific Types

Sigmoid Volvulus

• Most common site of colonic volvulus
• Predisposed: elderly, chronic constipation, redundant sigmoid on long mesentery, institutionalised patients
• AXR: "coffee bean" sign — massively distended sigmoid loop rising from the pelvis, midline crease
• CT: "whirl sign" (mesenteric torsion) + "bird's beak" sign (tapering at point of twist)
• Management: Flexible sigmoidoscopy/rigid proctoscopy for detorsion (first line if no peritonitis) → tube decompression → elective sigmoid resection after bowel prep; emergency Hartmann's if perforated/gangrenous

Caecal Volvulus

• Younger patients; axial twisting of mobile caecum
• AXR: distended oval structure in left upper quadrant ("coffee bean" pointing to LUQ)
• Management: right hemicolectomy (detorsion alone has high recurrence; caecostomy if too unstable)
• Caecal dilation >12–14 cm = surgical emergency (high perforation risk)

Gallstone Ileus

• Rare; large gallstone erodes through cholecystoduodenal fistula into small bowel
• Rigler's triad: SBO + pneumobilia + ectopic gallstone (usually at terminal ileum)
• Treatment: enterotomy and stone extraction ± cholecystectomy/fistula repair (staged)

Ileus vs. Mechanical Obstruction

Ileus Causes (common)

• Post-operative (normal ≤5 days after laparotomy)
  • Small bowel recovers: 24 hours; Stomach: 48 hours; Colon: 2–5 days
  • Bowel sounds returning is NOT a reliable indicator — flatus/stool is
• Sepsis, peritonitis, intra-abdominal abscess
• Electrolyte disturbance: hypokalaemia (most common), hypomagnesaemia, hyponatraemia
• Drugs: opiates, anticholinergics, phenothiazines, tricyclics, calcium channel blockers
• Retroperitoneal haematoma, spinal cord injury, MI, mesenteric ischaemia

Reducing Post-op Ileus

• Minimise bowel handling
• Laparoscopic approach
• Restrict intraoperative fluids
• Avoid NG tubes (if not essential)
• NSAIDs (ketorolac) + reduce opioids
• Thoracic epidural analgesia
• Chewing gum / early mobilisation / early feeding (ERAS protocols)

Management

Initial Resuscitation (All Obstruction)

• NBM
• IV access — fluid resuscitation (often dehydrated from vomiting + third-spacing)
• Correct electrolytes (especially K⁺)
• NG tube if vomiting/distension (decompression)
• Urinary catheter (fluid balance)
• Serial examinations — watch for strangulation features
• Bloods: FBC, U&E, LFTs, amylase, lactate, group & save, clotting

SBO — Non-operative Management (drip and suck)

• IV fluids, NGT, NBM
• Close monitoring (6-hourly obs, serial abdominal exams)
• Gastrografin challenge — therapeutic + prognostic
• Most adhesive SBOs (70–80%) resolve with conservative management
• Trial up to 48–72 hours for partial; less tolerance for complete

Indications for Emergency Surgery

• Signs of strangulation (peritonism, fever, tachycardia, rising lactate)
• Complete obstruction that fails conservative management
• Closed-loop obstruction
• Incarcerated/strangulated hernia (irreducible)
• Free perforation (pneumoperitoneum)
• Caecal diameter >12 cm (LBO)
• Volvulus with gangrenous bowel

Operative Options

Adhesion Prevention

• Good surgical technique, minimise peritoneal exposure to foreign material
• Laparoscopic surgery (4× lower risk of SBO vs. open at 5 years)
• Hyaluronan-based membrane (Seprafilm) reduces adhesion formation; effect on SBO incidence less clear; avoid wrapping anastomoses (increased leak rate)

Prognosis / Complications

• Strangulated obstruction carries significant mortality (~10–20% in delayed cases)
• Malignant bowel obstruction: median survival 3–4 months
• ~25–30% of patients with cancer and bowel obstruction have a benign cause (adhesions) — don't assume malignancy
• Post-op SBO recurrence risk after adhesiolysis remains significant; 30%+ hospital readmission rate within 10 years after colorectal/pelvic surgery