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COMPREHENSIVE SURGERY NOTES

Topics 11–20

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11. COLORECTAL TUMOURS

What Are They?

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Types of Colorectal Tumours

A. Benign Polyps (Pre-cancerous)

B. Malignant Tumours

• Adenocarcinoma — accounts for 95% of all colorectal cancers
• Carcinoid tumours — arise from neuroendocrine cells; mostly in rectum
• Lymphoma — rare
• Leiomyosarcoma — rare, from smooth muscle

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Risk Factors

• Dietary: High red/processed meat, low fibre, low fruit/vegetables, high fat intake
• Lifestyle: Obesity, physical inactivity, smoking, alcohol
• Genetic/Hereditary:
  • FAP (Familial Adenomatous Polyposis) — hundreds of polyps; APC gene mutation; near 100% cancer risk by age 40
  • HNPCC / Lynch Syndrome — DNA mismatch repair gene mutation; high risk of right-sided colon cancer
• Inflammatory Bowel Disease: Ulcerative colitis and Crohn's disease increase risk (longer duration = higher risk)
• Personal/family history of colorectal cancer or adenomas
• Age > 50 years

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Pathogenesis — The Adenoma–Carcinoma Sequence

1. APC gene mutation → polyp formation
2. K-RAS mutation → polyp growth
3. Loss of DCC (Deleted in Colorectal Cancer) gene
4. TP53 mutation → invasion and carcinoma

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Clinical Features (Symptoms)

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Staging — Duke's Classification (Simplified)

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Diagnosis

1. History and physical examination — including digital rectal examination (DRE)
2. Faecal occult blood test (FOBT) — screening tool
3. Colonoscopy — gold standard; allows biopsy and polypectomy
4. Sigmoidoscopy — for left-sided lesions
5. Barium enema — "apple-core" appearance of annular carcinoma
6. CT colonography (virtual colonoscopy) — non-invasive
7. CT scan (abdomen/pelvis/chest) — staging, liver metastases
8. MRI — especially for rectal cancer (assesses local spread)
9. CEA (Carcinoembryonic Antigen) — tumour marker; useful for monitoring recurrence, not for diagnosis
10. Biopsy — histological confirmation

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Treatment

Surgery (Curative Intent)

• Right hemicolectomy — for right colon tumours
• Left hemicolectomy / sigmoid colectomy — for left colon tumours
• Anterior resection — for upper rectal tumours
• Abdominoperineal resection (APR) — for very low rectal tumours; requires permanent colostomy
• Hartmann's procedure — for emergency obstruction/perforation (end colostomy + rectal stump)
• Aim for clear resection margins and adequate lymph node harvest (≥12 nodes)

Adjuvant (Post-operative) Treatment

• Chemotherapy: FOLFOX (5-FU + Oxaliplatin) for stage III (Duke's C)
• Radiotherapy: For rectal cancer — pre-operative (neoadjuvant) or post-operative
• Targeted therapy: Bevacizumab, Cetuximab for metastatic disease

Palliative Care (Metastatic Disease)

• Liver resection if solitary hepatic metastases
• Palliative chemotherapy
• Stenting for obstructing tumours

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Screening

• Average risk: Colonoscopy from age 50 every 10 years; FOBT annually
• High-risk (FAP): Colonoscopy from age 10–12
• Lynch syndrome: Colonoscopy from age 20–25

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12. BLUNT ABDOMINAL INJURIES

Definition

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Causes

• Road traffic accidents (RTAs) — most common cause (steering wheel, seat belt)
• Falls from a height
• Sports injuries, assault (punches, kicks)
• Explosions (blast wave)
• Industrial accidents

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Mechanism of Injury

1. Compression/crushing — direct blow squeezes hollow organs against the spine (e.g., bowel rupture)
2. Deceleration/shearing — sudden stopping tears organs at fixed attachment points (e.g., liver laceration at the hepatic veins, bowel tear at ligament of Treitz)
3. Burst injury — sudden increase in intra-abdominal pressure ruptures hollow viscera

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Organs Commonly Injured (in order of frequency)

1. Spleen — most commonly injured solid organ (vulnerable due to poor protection)
2. Liver — 2nd most common
3. Small bowel — most commonly injured hollow organ
4. Kidney
5. Mesentery
6. Pancreas — rare but serious
7. Duodenum — protected retroperitoneally but can rupture
8. Bladder — especially if full at time of impact

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Clinical Features

• Mechanism (seatbelt use, speed of collision, height of fall)
• Time of last meal (bowel contents affect contamination)

• Abdominal pain (may be diffuse or localised)
• Nausea, vomiting
• Signs of shock (tachycardia, hypotension, pallor) if significant haemorrhage

• Abdominal tenderness — guarding, rigidity (peritonism)
• Bruising: "Seatbelt sign" — transverse bruising across abdomen = high index of suspicion for bowel/mesenteric injury
• Grey Turner's sign — flank bruising = retroperitoneal haematoma (e.g., pancreatic or renal injury)
• Cullen's sign — periumbilical bruising = intraperitoneal blood
• Shoulder-tip pain — diaphragmatic irritation by blood (Kehr's sign for splenic injury)

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Assessment — ATLS Approach

• Airway, Breathing, Circulation (control haemorrhage), Disability (neurological status), Exposure (full examination)

1. FAST Scan (Focused Assessment with Sonography for Trauma) — rapid bedside ultrasound; detects free fluid (blood) in peritoneum; quick and repeatable
2. Diagnostic Peritoneal Lavage (DPL) — inject saline into peritoneum; positive if >100,000 RBC/mm³ in effluent; largely replaced by FAST
3. CT scan (abdomen/pelvis with contrast) — gold standard for stable patients; identifies organ injuries, grading, retroperitoneal injuries
4. Plain X-ray — erect CXR (free gas under diaphragm = bowel perforation), pelvic X-ray
5. FBC, U&E, amylase, LFTs, group and crossmatch, coagulation
6. Urinalysis — haematuria suggests renal/bladder injury

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Splenic Injury — Grading

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Management

Haemodynamically Unstable:

• Emergency laparotomy — immediate damage control surgery
• Pack and control bleeding, repair perforations
• Damage Control Surgery: Abbreviated initial operation → ICU resuscitation → definitive repair at 24–48 hours

Haemodynamically Stable:

• Non-operative management (NOM) — preferred for solid organ injuries (spleen, liver, kidney) when patient is stable
• Admit, close monitoring (pulse, BP, serial abdominal examinations, serial Hb)
• Angioembolisation — for ongoing bleeding from solid organs (interventional radiology)
• If patient deteriorates → laparotomy

• Vaccinate against encapsulated organisms: Pneumococcus, Meningococcus, Haemophilus influenzae (before surgery if elective, after if emergency)
• Life-long penicillin prophylaxis in children

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Key Surgical Procedures in Blunt Abdominal Trauma

• Splenectomy / splenorrhaphy (splenic repair)
• Hepatorraphy / packing for liver lacerations
• Bowel resection and anastomosis (or stoma if contaminated)
• Nephrectomy for severe renal injury
• Distal pancreatectomy for pancreatic injuries

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13. BLUNT CHEST INJURIES

Definition

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Causes

• Road traffic accidents
• Falls
• Sports injuries
• Assault
• Crush injuries

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Types of Blunt Chest Injuries

A. RIB FRACTURES

• Simple rib fractures: Pain on breathing; risk of pneumonia (splinting)
• Multiple rib fractures (≥3 ribs): More serious; risk of pneumo/haemothorax
• Flail chest: ≥3 consecutive ribs fractured in ≥2 places → "floating" segment moves paradoxically (inward on inspiration, outward on expiration). Causes severe respiratory failure. Management: mechanical ventilation, analgesia

• Adequate analgesia (key!) — epidural, intercostal nerve block, NSAIDs, opioids
• Incentive spirometry
• Physiotherapy to prevent pneumonia

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B. PNEUMOTHORAX

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C. HAEMOTHORAX

• Causes: Intercostal vessel or lung laceration
• Features: Dullness to percussion, reduced breath sounds, signs of haemorrhage
• Management:
  • Chest drain (large-bore, 28–32 Fr)
  • If initial drainage >1,500 mL OR ongoing >200 mL/hr for 2–4 hours → thoracotomy (massive haemothorax)
  • Retained haemothorax → fibrothorax (trapped lung) → VATS evacuation

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D. PULMONARY CONTUSION

• Bruising of lung parenchyma → oedema, haemorrhage → impaired gas exchange → hypoxia
• Most common cause of respiratory failure after blunt chest trauma
• Features: Hypoxaemia, crepitations, CXR shows patchy infiltrates
• Management: Supportive — oxygen, ventilation, fluid restriction, analgesia; may need mechanical ventilation

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E. CARDIAC TAMPONADE

• Blood in pericardial sac compresses the heart
• Beck's Triad: Hypotension + Distended neck veins + Muffled heart sounds
• ECG: low-voltage complexes, electrical alternans
• Echocardiogram confirms
• Management: Emergency pericardiocentesis (needle aspiration) → Surgical drainage (pericardial window)

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F. AORTIC INJURY

• Traumatic aortic rupture (deceleration injury) — most at the aortic isthmus (where aorta is tethered at ligamentum arteriosum)
• Often fatal at scene; those who survive have contained haematoma
• CXR: widened mediastinum, obliteration of aortic knuckle, left pleural effusion
• Confirmed by: CT aortogram or angiography
• Management: Endovascular aortic repair (EVAR/TEVAR) or open surgery

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G. TRAUMATIC DIAPHRAGMATIC RUPTURE

• Usually left-sided (liver protects right)
• Bowel/stomach herniates into chest
• CXR: nasogastric tube in chest, bowel loops in thorax
• Management: Surgical repair

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H. TRACHEOBRONCHIAL INJURY

• Rare; airway disruption near carina
• Features: Massive air leak, surgical emphysema, persistent pneumothorax despite drain
• Management: Bronchoscopy → surgical repair/bronchial sleeve resection

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Immediately Life-Threatening Chest Injuries — "ATOM FC"

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Management Approach

1. Primary survey (ABCDE) — identify and treat immediate threats
2. Supplemental O₂, monitoring, IV access
3. Analgesia — critical for respiratory effort
4. CXR (portable in trauma bay)
5. ECG, cardiac enzymes (troponin for myocardial contusion)
6. CT chest — for stable patients; details all injuries
7. Definitive management per injury type above

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14. PENETRATING ABDOMINAL INJURIES

Definition

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Causes

• Stab wounds (SW) — most common in civilian practice
• Gunshot wounds (GSW) — higher energy; more destructive; 80–95% cause significant intra-abdominal injury
• Impalement injuries — industrial, MVA
• Blast injuries (fragmentation)

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Mechanism

• Stab wounds: Low-velocity; injure structures directly in the path; less collateral damage
• Gunshot wounds (low-velocity, <600 m/s): Cause damage along missile path
• Gunshot wounds (high-velocity, >600 m/s — military weapons): Cause massive cavitation injury well beyond the bullet path (shock wave effect)

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Organs at Risk

• Liver — most commonly injured (right-sided wounds)
• Small bowel — large surface area; most commonly injured in GSWs
• Stomach
• Colon
• Major vessels (aorta, IVC, mesenteric vessels) — most lethal

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Clinical Features

• History: Type of weapon, direction of stab, calibre of firearm
• Symptoms: Abdominal pain, haemorrhage symptoms (hypotension, tachycardia, pallor)
• Signs:
  • Entry/exit wound (note: anterior vs. posterior; tangential vs. direct)
  • Evisceration (bowel or omentum protruding from wound)
  • Peritonism (guarding, rigidity, rebound tenderness)
  • Haemodynamic instability

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Indications for Immediate Emergency Laparotomy

1. Haemodynamic instability despite resuscitation
2. Peritonitis (diffuse guarding, rigidity) — 97% chance of significant injury
3. Evisceration of bowel/omentum
4. Uncontrolled haemorrhage
5. Unevaluable patient (head injury, spinal cord injury)
6. Air under diaphragm on X-ray

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Selective Non-Operative Management (NOM)

• Stab wounds: Up to 64% of anterior stab wounds do not require laparotomy
• Gunshot wounds: 47% can be managed without laparotomy
• Back/flank wounds: Even lower rates of significant injury; NOM preferred
• Requirements: Serial clinical examination, FAST scan, CT scan with contrast, observation in hospital

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Investigations

1. FAST ultrasound — rapid assessment for free fluid
2. CT scan (abdomen/pelvis) — essential for stable patients; plots missile trajectory, identifies injuries; use IV contrast
3. Plain X-rays — identifies bullet position and trajectory
4. Diagnostic Laparoscopy — can assess peritoneal penetration but NOT mandatory for this alone
5. Local wound exploration — can determine if anterior fascia is violated

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Management Principles

Resuscitation

• IV access (two large-bore IVs or central line), IV fluids
• Permissive hypotension (target SBP 80–90 mmHg) until haemorrhage controlled in unstable patients
• Massive transfusion protocol if needed (1:1:1 ratio of packed RBC:FFP:platelets)

Surgical Management

• Laparotomy (midline incision) — systematic exploration of all quadrants
• Damage control surgery in unstable patients:
  1. Control haemorrhage (packing, ligation)
  2. Control contamination (staple bowel ends, not formal anastomosis)
  3. Temporary abdominal closure
  4. ICU resuscitation
  5. Return to OR at 24–48 hours for definitive repair

Specific Injuries

• Liver: Packing, hepatorrhaphy, or formal resection
• Bowel: Primary repair (small injuries) or resection + anastomosis/stoma
• Vascular injuries: Vascular control, repair or ligation (mesenteric vessels)

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Wound Care

• Antibiotics (broad-spectrum, e.g., cephalosporins + metronidazole) — prophylactic, single dose or short course
• Tetanus prophylaxis
• Wound not primarily closed if contaminated

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15. MULTIPLY INJURED PATIENTS (POLYTRAUMA)

Definition

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Epidemiology

• Trauma is the leading cause of death in ages 1–44 years worldwide
• Trimodal distribution of trauma deaths:
  1. Immediate (seconds–minutes): Unsurvivable injuries (brain/aorta rupture)
  2. Early (minutes–hours): Preventable — hypoxia, haemorrhage ← golden hour
  3. Late (days–weeks): SIRS, sepsis, multi-organ failure

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Principles of Management — ATLS (Advanced Trauma Life Support)

Primary Survey — ABCDE (treat threats immediately as found)

Resuscitation

• Two large-bore IV cannulas (14G or 16G) in antecubital fossae
• Warm IV fluids — avoid hypothermia (part of the lethal triad)
• Massive Transfusion Protocol (MTP): Blood products in 1:1:1 ratio (RBC:FFP:Platelets)
• Avoid excessive crystalloids (worsens coagulopathy and tissue oedema)
• Tranexamic acid (TXA) — given within 3 hours of injury; reduces mortality from haemorrhage (CRASH-2 trial)

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The "Lethal Triad" of Trauma

1. Hypothermia (core temp <35°C)
2. Acidosis (base deficit >6, pH <7.35)
3. Coagulopathy (INR >1.5)

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Secondary Survey (Head-to-Toe)

• Complete head-to-toe physical examination
• Full history (AMPLE: Allergies, Medications, Past medical history, Last meal, Events)
• Identify all injuries missed in primary survey

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Key Investigations

• Full blood count, coagulation, group & crossmatch
• ABG (oxygenation, base deficit, lactate)
• Trauma CT ("pan-scan"): Whole body CT (head, cervical spine, chest, abdomen, pelvis) — standard for haemodynamically stable polytrauma
• Pelvis X-ray — in primary survey for haemodynamic instability
• FAST scan — bedside, repeated

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Damage Control Surgery (DCS)

1. Phase 0: Prehospital haemorrhage control (tourniquets, wound packing)
2. Phase 1: Abbreviated surgery — stop bleeding, stop contamination, temporary closure
3. Phase 2: ICU — warm, correct coagulopathy, treat acidosis
4. Phase 3: Definitive repair (24–72 hours later)
5. Phase 4: Abdominal closure, rehabilitation

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Priorities in Polytrauma

1. Airway obstruction
2. Tension pneumothorax
3. Haemorrhagic shock (external haemorrhage > internal)
4. Open chest wound
5. Cardiac tamponade
6. Head injury

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Complications of Polytrauma

• Acute Respiratory Distress Syndrome (ARDS)
• Systemic Inflammatory Response Syndrome (SIRS)
• Multi-organ dysfunction syndrome (MODS)
• Sepsis/infection
• Deep vein thrombosis (DVT) / pulmonary embolism
• Pressure injuries
• Psychological trauma (PTSD)

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16. ULCERS

Definition

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Types of Ulcers in Surgery

A. PEPTIC ULCER DISEASE (PUD)

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• H. pylori infection — present in 95% of duodenal ulcers, 70% of gastric ulcers (most important cause)
• NSAIDs/Aspirin — inhibit prostaglandins → impair mucosal barrier → 2nd most common cause
• Smoking — impairs healing, increases acid, reduces prostaglandins
• Steroids — reduce mucus production
• Zollinger-Ellison Syndrome — gastrinoma (tumour of G cells) → massive acid hypersecretion → severe refractory ulcers
• Stress ulcers — Curling's ulcer (burns), Cushing's ulcer (head injury)
• Blood group O — higher risk of duodenal ulcer

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• Epigastric pain — burning, gnawing
• Duodenal ulcer: Pain relieved by food ("hungry ulcer"); wakes patient at night; 2–3 hours after meals
• Gastric ulcer: Pain worsened by food; may have weight loss
• Nausea, vomiting, heartburn, bloating

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1. Endoscopy (OGD/gastroscopy) — gold standard; visualise, biopsy (exclude malignancy in gastric ulcers), test for H. pylori (CLO test/rapid urease test)
2. H. pylori testing:
   • Urea breath test (non-invasive, most accurate non-invasive)
   • Stool antigen test
   • Serology (IgG) — less accurate
   • Biopsy (CLO test, histology, culture)
3. Barium meal — "niche" (crater) appearance; largely replaced by endoscopy

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1. H. pylori eradication (triple therapy):
   • PPI (e.g., omeprazole 20 mg) + amoxicillin 1 g + clarithromycin 500 mg — all twice daily for 7–14 days
   • Test of cure with urea breath test 4–6 weeks after completion
2. Stop NSAIDs/aspirin (if possible) or add PPI cover
3. Acid suppression: PPI or H₂ antagonist for 4–8 weeks
4. Lifestyle: Stop smoking, reduce alcohol, avoid trigger foods

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B. LEG ULCERS (Chronic)

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17. FRACTURES

Definition

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Classification

By Skin Integrity

• Grade I: <1 cm wound, clean
• Grade II: 1–10 cm wound, moderate contamination
• Grade IIIA: >10 cm, adequate soft tissue cover
• Grade IIIB: >10 cm, periosteal stripping, needs flap
• Grade IIIC: Associated vascular injury requiring repair

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By Pattern

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Clinical Features

• Pain — at fracture site, worse on movement
• Tenderness — point tenderness over the fracture
• Swelling — due to haematoma and oedema
• Deformity — angulation, shortening, rotation
• Loss of function — inability to use the limb
• Abnormal mobility — movement where there should be none
• Crepitus — grating sensation (do NOT elicit deliberately)
• Neurovascular compromise — check distal pulse, sensation, motor function

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Diagnosis

1. X-ray — at least two views (AP and lateral); include the joint above and below
2. CT scan — for complex fractures (pelvis, spine, intra-articular)
3. MRI — for soft tissue, occult fractures, spinal cord assessment
4. Bone scan — for stress fractures

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Fracture Healing Stages

1. Haematoma formation (immediate, hours)
2. Inflammatory phase (days 1–5) — inflammatory cells clean the area
3. Soft callus formation (weeks 1–3) — fibrocartilage bridges the gap
4. Hard callus formation (weeks 3–12) — woven bone formed
5. Remodelling (months–years) — woven bone replaced by lamellar bone; fracture line disappears

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Principles of Fracture Management — "The 3 Rs"

1. Reduction — restore bone alignment
   • Closed reduction: Manual manipulation under anaesthesia
   • Open reduction: Surgical exposure
2. Immobilisation (Fixation) — hold the fracture reduced
   • External: Cast/splint/traction/external fixator
   • Internal: Plates & screws, intramedullary nail, wires
3. Rehabilitation — restore function
   • Physiotherapy, exercises to prevent stiffness and muscle wasting

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Specific Important Fractures

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Complications of Fractures

• Haemorrhage (internal or external)
• Neurovascular injury
• Organ injury (e.g., lung from rib, spinal cord from vertebral fracture)

• Compartment syndrome — raised pressure within osteofascial compartment → ischaemia → 4 P's: Pain (disproportionate), Paraesthesia, Pallor, Pulselessness; Treatment: Emergency fasciotomy
• Fat embolism syndrome
• Deep vein thrombosis
• Wound infection (open fractures)

• Malunion — heals in wrong position
• Delayed union — takes longer than expected
• Non-union — fails to heal (atrophic/hypertrophic)
• Avascular necrosis (AVN) — scaphoid, femoral head
• Osteoarthritis (if intra-articular)
• Osteomyelitis (infection in bone, especially open fractures)
• Contractures, myositis ossificans

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18. INTESTINAL OBSTRUCTION

Definition

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Types

A. Mechanical Obstruction

• Simple — one point of obstruction, blood supply intact
• Strangulated — blood supply compromised → ischaemia, necrosis, perforation → EMERGENCY

B. Adynamic Ileus (Paralytic Ileus)

• Post-operative (most common)
• Peritonitis
• Electrolyte imbalances (especially hypokalemia)
• Retroperitoneal haematoma
• Medications (opioids, anticholinergics)
• Spinal cord injury

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Causes of Mechanical Obstruction (Rosen's Emergency Medicine classification)

• Adhesions — #1 cause of small bowel obstruction (SBO); post-operative scarring
• Hernias (inguinal, femoral, incisional) — #2 cause of SBO; most common cause in patients with no previous surgery
• Volvulus — twisting of bowel around its mesenteric axis

• Carcinoma of the colon — #1 cause of large bowel obstruction (LBO)
• Crohn's disease (strictures)
• Diverticular disease (strictures)
• Intussusception — telescoping of bowel into itself (most common in children 6–18 months)

• Gallstone ileus
• Bezoars
• Foreign bodies
• Ascaris infestation (common in developing countries)

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Pathophysiology

1. Obstruction → bowel distension proximal to block (gas + fluid accumulation)
2. Bowel wall becomes oedematous → loss of absorptive function
3. Bacterial overgrowth in normally sterile small bowel → feculent vomiting
4. Fluid loss into lumen and peritoneal cavity → dehydration, electrolyte imbalance
5. If strangulation: venous occlusion → arterial occlusion → ischaemia → gangrene → perforation → peritonitis → septic shock

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Clinical Features

• Constant (not colicky) severe pain
• Fever, tachycardia
• Localised tenderness, peritonism
• Raised WBC
• Acidosis

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Investigations

1. Plain abdominal X-ray (erect + supine)
   • SBO: Dilated loops of small bowel (central, valvulae conniventes crossing entire lumen), fluid levels
   • LBO: Peripheral colonic distension (haustral folds don't cross entire lumen), "coffee bean sign" in sigmoid volvulus
   • Free gas under diaphragm if perforated
2. CT abdomen — gold standard; identifies cause, level, and strangulation
3. Gastrografin/barium follow-through — for partial SBO (can be therapeutic for adhesions)
4. Blood tests: FBC (raised WBC in strangulation), U&E (electrolytes), LFTs, lactate, group & save

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Management

General (All Types):

• "Drip and suck": IV fluids (correct dehydration) + nasogastric tube (decompress stomach)
• Urinary catheter (monitor output)
• NBM (nil by mouth)
• Analgesia
• Correct electrolytes (especially K⁺)
• Monitor closely for signs of strangulation

Small Bowel Obstruction — Adhesional (Most Common):

• Conservative management first — 70–80% resolve with drip and suck
• Water-soluble contrast study (Gastrografin) — therapeutic (reduces adhesions) and diagnostic
• Surgery if: No improvement in 48–72 hours, strangulation suspected, complete obstruction with closed loop

Large Bowel Obstruction:

• Most require urgent surgery
• Sigmoid volvulus: First attempt colonoscopic/sigmoidoscopic decompression (pass flatus tube)
• Caecal volvulus: Requires surgery
• Carcinoma causing obstruction:
  • Hartmann's procedure — sigmoid colectomy with end colostomy (safest in emergency)
  • Primary resection and anastomosis (in specialist centres)
  • Self-expanding metallic stents (SEMS) — bridge to elective surgery

Strangulation → Emergency Laparotomy

• Resect non-viable bowel
• Assess viability (colour, peristalsis, Doppler signal)
• If uncertain: second-look laparotomy at 24–48 hours

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19. ACUTE APPENDICITIS

Definition

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Anatomy

• The vermiform appendix is a blind-ended diverticulum arising from the posteromedial wall of the caecum at the confluence of the taenia coli
• Length: 2–20 cm (average 9 cm)
• Blood supply: Appendicular artery (branch of ileocolic artery)
• Position varies: Retrocaecal (most common, 65%), pelvic, subcaecal, pre-ileal, post-ileal

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Epidemiology

• Lifetime risk: 8.6% males, 6.7% females
• Peak age: 10–30 years (but occurs at any age)
• Accounts for 30% of acute surgical emergencies under 50 years
• ~318,000 hospital admissions per year in the USA

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Pathogenesis

1. Luminal obstruction — most common cause: faecolith (hardened faeces), lymphoid hyperplasia (in children, following viral illness), tumour, foreign body, worm (Oxyuris/Ascaris)
2. Obstruction → continued mucus secretion → rising intraluminal pressure
3. Venous congestion → mucosal ischaemia
4. Bacterial invasion of wall (E. coli, Bacteroides, Klebsiella)
5. Inflammation → transmural infection → gangrene → perforation

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Clinical Features

1. Prodromal symptoms: Anorexia, nausea, low-grade fever (up to 38°C)
2. Pain migration: Initially periumbilical (visceral pain via T10) → within 6–8 hours migrates to right iliac fossa (RIF) as parietal peritoneum is involved
3. Vomiting — usually after pain onset (distinguishes from gastroenteritis)
4. Low-grade fever (>38.5°C suggests perforation)
5. Constipation (occasionally diarrhoea with pelvic appendix)

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Alvarado Score (MANTRELS)

• Score 1–4: Appendicitis unlikely
• Score 5–6: Possible appendicitis — further investigation
• Score 7–8: Probable appendicitis — consider surgery
• Score 9–10: Appendicitis very likely — operate

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Investigations

1. FBC — leucocytosis (WBC >10,000 in 70–90%); neutrophilia
2. CRP — elevated; rises more slowly than WBC
3. Urinalysis — to exclude UTI/renal colic (may have mild pyuria with appendicitis — pelvic appendix)
4. Beta-hCG — in all women of childbearing age (exclude ectopic pregnancy)
5. Ultrasound (USS) — operator-dependent; visualises non-compressible appendix >6 mm diameter; free fluid; useful in children and pregnant women
6. CT scan (abdomen/pelvis) — most accurate (sensitivity/specificity >95%); used in adults when diagnosis uncertain; shows thickened appendix with periappendiceal fat stranding
7. MRI — preferred in pregnancy

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Differential Diagnosis

• Mesenteric adenitis (children)
• Ovarian pathology (ectopic pregnancy, ovarian cyst/torsion) — in women
• Urinary tract infection/renal colic
• Crohn's disease
• Meckel's diverticulitis
• Pelvic inflammatory disease (PID)
• Testicular torsion (referred RIF pain)

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Complications

1. Perforation — 20–30% of cases; higher in elderly and very young (atypical presentation)
2. Appendix mass — contained perforation with omentum walling off; managed conservatively initially (Ochsner-Sherren regimen), elective appendicectomy 6–8 weeks later
3. Appendix abscess — requires drainage (radiological or surgical) + antibiotics, then interval appendicectomy
4. Generalised peritonitis — free perforation → emergency surgery
5. Pylephlebitis — portal vein thrombosis (rare but serious)

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Treatment

Non-Perforated Appendicitis

• Appendicectomy — definitive treatment; laparoscopic approach preferred (shorter hospital stay, less pain, quicker return to work)
• Open appendicectomy — Gridiron (McBurney's) incision in RIF, or Lanz incision
• Antibiotic therapy alone — emerging evidence (APPAC trial) that antibiotics alone may treat uncomplicated appendicitis in some patients; however, recurrence rate ~39% at 10 years; not yet standard in most settings

Perforated Appendicitis / Peritonitis

• Emergency laparotomy or laparoscopy
• Appendicectomy + peritoneal lavage
• IV antibiotics (broad-spectrum: e.g., cefuroxime + metronidazole; or piperacillin-tazobactam)

• IV fluids, analgesia (does NOT mask signs)
• IV antibiotics (prophylactic dose at induction)
• Catheter if needed
• NBM

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20. EXTERNAL HERNIAS

Definition

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Anatomy of a Hernia

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Types of External Hernias

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Inguinal Hernia — In Detail

• Anterior wall: External oblique aponeurosis (reinforced laterally by internal oblique)
• Posterior wall: Transversalis fascia (reinforced medially by conjoint tendon)
• Floor: Inguinal ligament
• Roof: Arching fibres of internal oblique + transversus abdominis

• Indirect: Lateral to inferior epigastric vessels; through deep ring; congenital (patent processus vaginalis) or acquired; can strangulate
• Direct: Medial to inferior epigastric vessels; through Hesselbach's triangle; acquired weakness; rarely strangulates

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Clinical Features of Hernia

• Lump in the groin/abdomen/scrotum
• Aching discomfort (especially on standing, straining, or coughing)
• May be asymptomatic

• Reducible lump that becomes prominent on coughing/straining
• Expansile cough impulse
• Inguinal canal examination: Finger invagination into superficial inguinal ring

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States of a Hernia — Critical Definitions

• Sudden increase in pain (constant, not intermittent)
• Tense, tender, irreducible swelling
• Vomiting, features of bowel obstruction
• Absent cough impulse
• Systemic upset (fever, tachycardia)

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Investigations

• Usually clinical diagnosis
• Ultrasound — if diagnosis uncertain, impalpable hernia
• CT scan — for complex/recurrent hernias, to identify Spigelian or obturator hernias
• Herniogram — rarely used now

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Treatment

Conservative (Observation)

• Asymptomatic inguinal hernias (especially in elderly/high surgical risk): "watchful waiting" is safe in the short term
• Truss (external support): Rarely used; does not cure hernia

Surgical Repair — Principles

• Low approach (Lockwood): Through groin
• High approach (McEvedy): Through abdomen; better for strangulation
• Laparoscopic: TEP/TAPP

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Complications of Hernia Repair

• Immediate: Haemorrhage, injury to bowel/bladder/vas deferens/femoral vessels
• Early: Wound infection, haematoma, urinary retention, ileus
• Late: Chronic groin pain (most common after Lichtenstein), mesh infection, mesh migration, recurrence (most important — approximately 1–5% with mesh, higher with non-mesh repairs), testicular atrophy (injury to testicular vessels), hydrocele

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Special Situations

• Strangulated hernia with gangrenous bowel: Resect bowel, primary anastomosis vs. stoma; delayed mesh placement (contaminated field)
• Paediatric inguinal hernia: All require surgery (high rate of incarceration); herniotomy (ligation of sac) without mesh
• Femoral hernia: Repair should be prompt even if asymptomatic (high strangulation rate)

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QUICK SUMMARY TABLE

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