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MS General Surgery - University Examination Answers

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QUESTION 1 (30 marks)

Pathophysiological Changes in Laparoscopic Surgery and Prevention of Related Complications

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INTRODUCTION

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I. PNEUMOPERITONEUM: CREATION AND BASICS

• Standard intraabdominal pressure (IAP): 12-15 mmHg (working pressure); up to 20 mmHg used occasionally
• CO2 is the gas of choice because it is:
  • Non-flammable (safe with electrocautery)
  • Highly soluble in blood (rapidly absorbed and excreted via lungs)
  • Inexpensive and readily available
• Introduced via Veress needle or Hasson (open) technique

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II. CARDIOVASCULAR EFFECTS

A. Effect of Increased IAP

• Increased systemic vascular resistance (SVR) due to neurohumoral activation (renin-angiotensin-aldosterone, vasopressin release)
• Decreased cardiac output (5-30% reduction)
• Increased mean arterial pressure
• Increased heart rate (reflex from vagal stimulation or CO2 absorption)
• Decreased portal and hepatic blood flow (up to 40%)
• Decreased renal blood flow and GFR

B. CO2 Absorption Effects

• Absorbed CO2 causes hypercapnia and acidosis
• Hypercarbia causes peripheral vasodilation but pulmonary vasoconstriction
• Stimulates sympathetic system → tachycardia, hypertension, arrhythmias

C. Position-Related Effects

• Trendelenburg (pelvis up): Increases cardiac output, increases intracranial and intraocular pressure, increases risk of regurgitation
• Reverse Trendelenburg (head up): Decreases cardiac output and venous return, pooling in lower limbs

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III. RESPIRATORY EFFECTS

1. Diaphragm elevation due to raised IAP → reduced functional residual capacity (FRC)
2. Increased airway resistance and peak airway pressure
3. Ventilation-perfusion (V/Q) mismatch - dependent lung zones become relatively underventilated
4. CO2 absorption from peritoneum → hypercapnia → respiratory acidosis
5. In spontaneously breathing patients: risk of hypercarbia and CO2 narcosis
6. CO2 embolism - rare but life-threatening; causes acute cardiovascular collapse
7. Endobronchial intubation risk in steep Trendelenburg (cephalad shift of carina)

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IV. RENAL EFFECTS

1. Raised IAP compresses renal vasculature → decreased renal blood flow (up to 60%)
2. Decreased GFR and urine output (oliguria common; not true renal failure)
3. Elevated antidiuretic hormone (ADH) and aldosterone levels → sodium and water retention
4. Mechanism: direct compression + neurohormonal activation + decreased cardiac output
5. Usually reversible on desufflation

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V. NEUROHUMORAL AND METABOLIC EFFECTS

1. Cortisol, catecholamines, growth hormone levels increase (stress response, but less than in open surgery)
2. Vasopressin (ADH) markedly elevated - causes vasoconstriction and oliguria
3. Renin-Angiotensin-Aldosterone System (RAAS) activated by renal hypoperfusion
4. CO2 absorption → carbonic acid formation → metabolic and respiratory acidosis
5. Immunological advantage: Laparoscopy preserves immune function better than open surgery (reduced cytokine release, better NK cell preservation)

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VI. EFFECTS ON THE PORTAL AND SPLANCHNIC CIRCULATION

1. Portal blood flow decreases by 35-40% at 15 mmHg IAP
2. Liver blood flow decreases → risk in patients with pre-existing hepatic disease
3. Mesenteric ischemia is possible at high IAP
4. Bowel wall ischemia rare but can occur with IAP >20 mmHg

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VII. NEUROLOGICAL EFFECTS

1. Increased intracranial pressure (ICP): Trendelenburg position + CO2 absorption + raised IAP all contribute
2. Increased intraocular pressure
3. Contraindicated/used with caution in: raised ICP (head injury, VP shunt), glaucoma

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VIII. THROMBOTIC AND HAEMATOLOGICAL EFFECTS

1. Venous stasis in lower limbs due to raised IAP + positioning
2. Deep vein thrombosis (DVT) and pulmonary embolism (PE) risk increased
3. Venous stasis causes activation of coagulation cascade
4. Fibrinolysis is better preserved in laparoscopy vs open surgery

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IX. SPECIFIC COMPLICATIONS AND PREVENTION

A. Entry-Related Complications

B. CO2-Related Complications

C. Cardiovascular Complications

• Arrhythmias: pre-oxygenate, maintain normocarbia, avoid vagal stimulation
• Hypotension: reduce IAP, fluid resuscitation, vasopressors if needed
• DVT: pneumatic compression stockings, LMWH, early mobilization

D. Trocar Site Complications

E. Physiological Precautions

1. Patient selection: Contraindications include severe COPD, uncorrected coagulopathy, bowel obstruction with massive distension, hemodynamic instability
2. Low IAP technique: Gasless laparoscopy (abdominal wall lift) in high-risk patients
3. ETCO2 monitoring: Maintain 35-40 mmHg by adjusting ventilation
4. IAP monitoring: Maintain <15 mmHg; desufflate if cardiovascular compromise
5. Head-down position: Minimize time in steep Trendelenburg; use ramp positioning
6. Intermittent pneumatic compression devices: Applied before induction
7. Warm, humidified CO2: Reduces hypothermia, reduces peritoneal damage

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X. ADVANTAGES OF LAPAROSCOPY OVER OPEN SURGERY (Physiological Basis)

• Smaller incisions → less pain, less ileus, faster return of gut function
• Reduced wound infection, incisional hernia rates
• Reduced blood loss and fluid shifts
• Better preservation of immunity (less IL-6, TNF-alpha release)
• Faster recovery and shorter hospital stay

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QUESTION 2 (10 marks)

Professional Hazards of Surgeons

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I. PHYSICAL HAZARDS

A. Musculoskeletal Disorders

• The most common occupational hazard (affecting >80% of surgeons)
• Causes: Prolonged standing, static postures, ergonomically poor instrument design (especially laparoscopic instruments)
• Sites: Neck, back (lumbar), shoulders, hands/wrists
• Conditions: Occupational low back pain, cervical spondylosis, carpal tunnel syndrome, de Quervain's tenosynovitis, trigger finger
• Prevention: Ergonomic theatre setup, adjustable table height, anti-fatigue mats, regular stretching, monitor height adjustment in laparoscopy

B. Radiation Hazards

• Exposure during C-arm fluoroscopy (orthopaedic, vascular, endoscopic procedures), nuclear medicine procedures
• Risks: Cumulative DNA damage, cataracts (lens of eye most sensitive), thyroid cancer, leukaemia, dermatitis
• Prevention:
  • Lead aprons (minimum 0.25 mm lead equivalent), thyroid shields, lead glasses
  • Distance (inverse square law)
  • Minimize fluoroscopy time
  • Radiation dosimetry badges (TLD/film badges)
  • Adherence to ALARA principle (As Low As Reasonably Achievable)

C. Noise-Induced Hearing Loss

• Prolonged exposure to theatre equipment (ultrasonic dissectors, suction devices, alarms)

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II. BIOLOGICAL HAZARDS

A. Bloodborne Pathogen Exposure

• Needle stick injuries and sharps injuries (most common route)
• Pathogens: HIV, HBV, HCV
• Risk per exposure: HIV ~0.3%, HCV ~3%, HBV ~30% (unvaccinated)
• Prevention:
  • Hepatitis B vaccination (mandatory for healthcare workers)
  • Double-gloving (reduces inner glove perforation by 70%)
  • No-touch technique (passing sharps in kidney dish, not hand-to-hand)
  • Blunt-tip needles for closure
  • Puncture-resistant gloves for high-risk procedures
  • Post-exposure prophylaxis (PEP) for HIV within 72 hours

B. Surgical Smoke Hazards

• Electrocautery, laser, and ultrasonic devices generate surgical plume
• Contains: viral DNA/RNA (HPV has been detected), carcinogenic particles (benzene, formaldehyde), aerosolized bacteria
• Prevention: Smoke evacuation systems, appropriate masks (N95 for known viral cases)

C. Latex Allergy

• Repeated glove use → sensitization → type I (anaphylaxis) or type IV (contact dermatitis) hypersensitivity
• Prevention: Latex-free gloves, early identification of sensitized individuals

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III. CHEMICAL HAZARDS

• Glutaraldehyde (instrument sterilization): skin sensitization, asthma, eye irritation
• Anaesthetic gases (nitrous oxide, halogenated agents): chronic exposure → hepatotoxicity, nephrotoxicity, reproductive effects
• Formalin/formaldehyde (pathology handling): carcinogen (nasopharyngeal cancer)
• Methyl methacrylate (bone cement in orthopaedics): sensitizer, teratogen
• Prevention: Adequate ventilation, scavenging systems, PPE, occupational exposure limits (OELs)

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IV. PSYCHOLOGICAL HAZARDS

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V. ERGONOMIC AND WORKPLACE HAZARDS

• Fatigue from long operating lists and night calls: Increases error rate (comparable to 0.05% blood alcohol)
• Eye strain: From microscopes, loupes, bright xenon lights
• Hypothermia: Cold theatre environments
• Diathermy/electrosurgical burns: Through faulty equipment

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VI. MEDICOLEGAL AND ETHICAL HAZARDS

• Risk of litigation, criminal prosecution
• Boundary violations
• Academic integrity issues

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QUESTION 3 (30 marks)

Hand-Sewn vs Stapled Intestinal Anastomosis: Principles, Advantages, Disadvantages, Techniques, and Available Staplers

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I. PRINCIPLES OF INTESTINAL ANASTOMOSIS

1. Adequate blood supply - the single most important factor
2. Tension-free approximation - mesentery adequately mobilized
3. No distal obstruction
4. Healthy bowel ends - viable, no ischaemia, no inflammation/radiation damage
5. Watertight apposition - mucosa-to-mucosa (inverting) or all-layer (everting) contact
6. No faecal loading - bowel preparation or on-table lavage if needed
7. Good nutritional status (serum albumin >30 g/L)
8. Absence of infection/peritoneal contamination

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II. HAND-SEWN ANASTOMOSIS

A. Historical Context

B. Types of Sutures Used

• Absorbable: Polyglactin (Vicryl), Polyglycolic acid (Dexon), PDS (polydioxanone)
• Non-absorbable: Prolene (polypropylene) - used for vascular anastomoses

C. Suture Techniques

D. Layers

• Inner layer: Continuous Connell or Vicryl (all layers, inverting)
• Outer layer: Interrupted/continuous Lembert (seromuscular)
• Advantage: More secure, traditional; better in contaminated fields
• Disadvantage: Greater luminal narrowing, more ischaemia, technically more demanding

• Full-thickness interrupted or continuous sutures, usually extramucosal
• Advantage: Less ischaemia, adequate lumen, equal leak rate to two-layer
• Evidence (RCTs) shows no significant difference in leak rate between single and double layer

E. Configuration Options

• End-to-End (EEA): Bowel continuity restored; risk of stricture if size mismatch
• End-to-Side (ESA): Used when size mismatch or end-to-end not feasible (e.g., ileocolic)
• Side-to-Side (SSA): Larger anastomosis, less risk of stricture; standard for Billroth II, Roux-en-Y

F. Advantages of Hand-Sewn Anastomosis

1. No device cost
2. Applicable to any bowel caliber, any configuration
3. Surgeon has tactile feedback and can assess tissue quality
4. Possible in difficult anatomical locations (deep pelvis, oesophageal anastomosis)
5. Safer in contaminated/hostile fields
6. Allows fine tissue adjustment, especially with size discrepancy
7. Does not leave foreign material (metal staples) in situ

G. Disadvantages of Hand-Sewn Anastomosis

1. Technically demanding - steep learning curve
2. Time-consuming
3. Requires adequate exposure
4. Greater intraoperative bowel handling and spillage risk
5. Increased operating time increases anaesthetic risk
6. More technically variable (operator-dependent)

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III. STAPLED ANASTOMOSIS

A. Historical Context

B. Mechanism

C. Techniques of Stapled Anastomosis

• Used for colorectal, oesophagogastric anastomoses
• Anvil placed in proximal bowel with purse-string suture
• Stapler body inserted transanally (or via gastrotomy)
• Stapler fires: creates double-staggered row of staples + cuts out donuts
• "Donuts" (tissue rings) inspected for completeness
• Leak test mandatory with air or methylene blue

• Most common technique for ileocolic and small bowel anastomoses
• Both ends of bowel held parallel; enterotomies made on antimesenteric borders
• GIA/linear cutter stapler inserted and fired (creates side-to-side anastomosis)
• Common enterotomy closed with linear (TA) stapler or hand-sewn
• Creates a wide, well-vascularised anastomosis with low leak rate

• Used for Billroth II, jejunojejunostomy in Roux-en-Y

D. Advantages of Stapled Anastomosis

1. Faster - significantly reduces operative time
2. Reproducible - less operator-dependent
3. Enables low pelvic and intrathoracic anastomoses - areas inaccessible to hand suturing
4. Uniform staple formation - consistent tissue inversion and haemostasis
5. Less bowel handling - reduced spillage and contamination
6. Creates a wider lumen (especially functional EEA)
7. Better for laparoscopic surgery - hand suturing difficult intracorporeally
8. Equal or superior leak rates compared to hand-sewn in many series
9. Reduced operative blood loss

E. Disadvantages of Stapled Anastomosis

1. Expensive (cost per stapler: Rs 3,000-15,000 in India)
2. Stricture formation - especially circular staplers (EEA); incidence 5-20%
3. Staple line bleeding - if not properly compressed
4. Incomplete donuts indicate defective anastomosis
5. Cannot be used in very small bowel (<2 cm diameter)
6. Not ideal in grossly contaminated fields (staples do not fire well in friable tissue)
7. Device malfunction - misfires, incomplete staple formation, knife failure
8. Foreign body - titanium staples remain permanently
9. Learning curve for correct deployment

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IV. COMPARISON TABLE: HAND-SEWN vs STAPLED

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V. STAPLERS AVAILABLE FOR INTESTINAL ANASTOMOSIS

A. Linear Staplers (TA - Thoracoabdominal / Roticulator)

B. Circular Staplers (EEA - End-to-End Anastomosis)

C. Endoscopic (Laparoscopic) Staplers

D. Specialty Staplers

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VI. SPECIFIC APPLICATIONS

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QUESTION 4 (10 marks)

Replantation of Limb

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I. DEFINITION

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II. HISTORY

• 1962: Malt and McKhann - first successful upper limb replantation (12-year-old boy, arm amputated by train)
• 1968: Komatsu and Tamai - first successful digital replantation
• Modern replantation uses the operating microscope and microsurgical instruments for anastomosis of vessels 1-3 mm in diameter

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III. INDICATIONS (what to replant)

• Thumb amputation (thumb constitutes 40-50% of hand function; virtually always indicated)
• Multiple digit amputations
• Amputation through palm or wrist
• Pediatric amputations (excellent recovery potential)
• Isolated single-digit amputation distal to FDS insertion (zone I)
• Major upper limb amputations (arm, forearm, elbow level)

• Isolated single digit (zone II - controversial, poorer results)
• Lower limb amputations - more controversial (poor functional recovery, high morbidity)

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IV. CONTRAINDICATIONS

• Severely crushed, mangled, or avulsed parts (avulsion injury - "degloving" from ring avulsion)
• Prolonged ischaemia (>6 hours warm, >12-24 hours cold for digits; lower tolerance for proximal amputations due to muscle mass)
• Multilevel injury
• Hemodynamically unstable patient
• Severe associated injuries (prioritise life over limb)

• Single digit amputation (zone II)
• Extreme contamination
• Patient age (elderly with comorbidities - poor rehabilitation potential)
• Patient preference/occupation

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V. ISCHAEMIA TIME LIMITS

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VI. TRANSPORT OF AMPUTATED PART

1. Wrap amputated part in moist normal saline gauze
2. Place in a sealed plastic bag
3. Place bag in ice-water mixture (0-4°C)
4. Never place part directly on ice (causes frostbite)
5. Never use dry ice (causes frostbite)

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VII. SEQUENCE OF REPLANTATION (MNEMONIC: B-B-T-A-V-N-S)

1. B - Bone shortening and fixation (K-wires, mini-plates, intramedullary wires)
2. B - Back of hand (Extensor tendons) repair
3. T - Tendons (Flexor) repair
4. A - Arteries - microsurgical repair (usually at least one artery)
5. V - Veins - microsurgical repair (2:1 ratio of veins to arteries preferred)
6. N - Nerves - coaptation (immediate or delayed)
7. S - Skin - closure (split-thickness skin graft if needed; no tension)

• Bone stabilization first provides a stable platform for vascular repair
• Arterial repair done before venous to reduce ischaemia time
• Some surgeons do rapid arterial shunting first (temporary intraluminal shunt) to restore perfusion while doing bone/tendon work

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VIII. SURGICAL TECHNIQUE - KEY POINTS

• Two teams simultaneously: one prepares patient/recipient site, one prepares amputated part
• Regional anesthesia preferred (sympathectomy effect → vasodilation)
• Anticoagulation: heparin intraoperatively

• Shorten by 1-2 cm to relieve tension on vessels/nerves
• K-wire or mini-plate fixation

• Operating microscope (6-40x magnification)
• 10-0 or 11-0 monofilament nylon (Prolene/nylon) sutures
• Interrupted sutures for vessel anastomosis
• Vessel ends cut clean, adventitia stripped 2-3 mm
• Papaverine/lignocaine to relieve vasospasm
• Repair arteries first, then veins
• Must repair minimum 1 artery and 2 veins per digit

• End-to-end coaptation with 9-0 or 10-0 nylon
• Epineural sutures
• If gap >3 cm: nerve graft (sural nerve)

• Hourly checks of capillary refill, colour, temperature, turgor
• Temperature difference >2°C between replanted and normal digit = vascular compromise
• Doppler ultrasound for vessel patency
• Anticoagulation: aspirin, heparin, low molecular weight dextran (dextran-40)
• Warm environment (25-28°C) to prevent vasospasm
• No smoking (nicotine causes vasospasm)
• Elevation to reduce oedema

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IX. POSTOPERATIVE COMPLICATIONS

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X. FUNCTIONAL OUTCOMES

• Overall digit survival rate: 80-90% (modern series)
• Two-point discrimination: Median 8-12 mm (normal <6 mm)
• Grip strength: ~60-70% of normal
• Thumb replantation: Best functional results
• Children: Best recovery (neuroplasticity, growth potential)
• Prognostic factors for good outcome:
  • Sharp/guillotine amputation (vs crush/avulsion)
  • Distal level
  • Young age
  • Short ischaemia time
  • Experienced microsurgical team

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XI. REHABILITATION

• Phase 1 (0-4 weeks): Immobilization, wound care, oedema control
• Phase 2 (4-8 weeks): Gentle active and passive range-of-motion exercises
• Phase 3 (8-12 weeks): Strengthening, desensitization
• Phase 4 (3-12 months): Functional retraining, vocational rehabilitation
• Tenolysis, nerve decompression, or secondary tendon grafting may be required at 6-12 months if function inadequate

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