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MS General Surgery - June 2025 Supplementary Examination

Complete Model Answers

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Q.1 (30 Marks): Pheochromocytoma - Pathophysiology, Clinical Features, Diagnosis & Management

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INTRODUCTION

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PATHOPHYSIOLOGY

Origin & Biosynthesis

• Arises from neural crest-derived chromaffin cells of the adrenal medulla
• Tumor cells synthesize, store, and secrete catecholamines: epinephrine (Epi), norepinephrine (NE), and dopamine
• Biosynthetic pathway: Tyrosine → DOPA → Dopamine → NE → Epinephrine (via PNMT enzyme, present mainly in adrenal medulla)
• Most adrenal pheos secrete both Epi and NE; extra-adrenal ones secrete predominantly NE (lack PNMT)

Effects of Catecholamine Excess

• NE-secreting tumors: predominantly hypertension (α1 effect)
• Epi-secreting tumors: hypertension + tachycardia + hypotension (β2 vasodilation)
• Chronic catecholamine excess leads to: catecholamine cardiomyopathy, reduced plasma volume (alpha-mediated vasoconstriction), and paradoxical hypotension post-tumor manipulation

Metabolic Effects

• Increased glycogenolysis and gluconeogenesis → hyperglycemia
• Increased lipolysis → elevated free fatty acids
• Basal metabolic rate elevated → hyperhidrosis, weight loss

Genetic Associations (Familial ~25-30%)

• MEN2A/2B (RET mutation): pheo + medullary thyroid cancer ± parathyroid hyperplasia
• VHL disease (VHL mutation): pheo + hemangioblastoma + clear cell RCC
• NF-1 (neurofibromatosis): pheo in 1-5%
• SDH mutations (SDHB, SDHC, SDHD): hereditary paraganglioma-pheo syndrome (SDHB → malignant)

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CLINICAL FEATURES

Classic Triad (Whipple's triad equivalent for pheo):

Symptoms

• Hypertension (90%): sustained (50-60%) or paroxysmal (40-50%)
• Severe headache (often throbbing, 80%)
• Palpitations and tachycardia (70%)
• Profuse sweating (60%)
• Pallor (not flushing - sympathetic vasoconstriction)
• Tremor, anxiety, sense of impending doom
• Nausea, vomiting
• Weight loss, heat intolerance
• Hyperglycemia / diabetes mellitus
• Hypertensive crisis triggered by: tumor palpation, anesthesia induction, micturition (bladder pheo), trauma, certain drugs (beta-blockers, metoclopramide, tricyclics)

Signs

• Hypertension (may be labile)
• Orthostatic hypotension (reduced plasma volume)
• Tachycardia
• Pallor during attacks
• Retinal changes of hypertension
• Catecholamine cardiomyopathy: dilated or hypertrophic cardiomyopathy

The "5 P's" of Pheochromocytoma:

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DIAGNOSIS

Biochemical Tests (Step 1 - Confirm hormonal excess)

• Sensitivity ~99%, Specificity ~89%
• Catecholamines are metabolized to metanephrines WITHIN the tumor continuously (not just during secretory episodes)
• Best screening test

• Urine metanephrines (sensitivity 97%)
• Urine vanillylmandelic acid (VMA) - historical test, lower sensitivity
• Urine total catecholamines
• Values >2x upper limit of normal are highly diagnostic

• Used in borderline cases
• Clonidine suppresses sympathetic NE but NOT tumor-secreted NE
• Failure to suppress plasma NE by >50% after 3 hours = positive test

Localizing Tests (Step 2 - After biochemical confirmation)

• First-line imaging
• Adrenal pheo: round/oval, >3 cm, heterogeneous (central necrosis/hemorrhage), high Hounsfield units (>10 HU on unenhanced)
• Cannot distinguish functional from non-functional

• Superior for extra-adrenal disease, pregnancy, children
• T2-weighted: characteristically bright ("light bulb" sign) - T2 hyperintense
• Better soft-tissue contrast, no radiation

• Functional imaging; MIBG is a NE analog taken up by adrenergic tissue
• Sensitivity ~85%, Specificity ~99%
• Essential for: extra-adrenal disease, metastatic disease, post-surgical surveillance
• Therapeutic MIBG also used for malignant pheo

• F-18 FDG PET: for SDHB-related/malignant pheo
• Ga-68 DOTATATE PET: highly sensitive for paragangliomas

Histology

• Chromogranin A, synaptophysin positive (neuroendocrine markers)
• S100 positive (sustentacular cells at periphery)
• Malignancy defined by METASTASIS (lymph nodes, liver, lung, bone), not histological features alone
• PASS score (Pheochromocytoma of Adrenal Scaled Score) and GAPP score help predict malignant behavior

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MANAGEMENT

Pre-operative Preparation (CRITICAL - minimum 10-14 days)

• Phenoxybenzamine (non-selective, irreversible alpha-blocker): Start 10 mg BD, increase to 20-40 mg TDS
  • Causes orthostatic hypotension, nasal stuffiness, reflex tachycardia
• OR Doxazosin/Prazosin (selective alpha-1 blockers): better tolerated, fewer side effects
• Goal: BP <130/80 mmHg sitting, no orthostatic hypotension <80/45 mmHg

• Beta-blockade before alpha-blockade can cause catastrophic hypertensive crisis (unopposed alpha stimulation)
• Propranolol 10-40 mg TDS, for tachycardia (HR <90 bpm)

• High-salt diet and IV fluids pre-op to expand contracted plasma volume
• Prevents post-resection hypotension

• Amlodipine, nifedipine - adjunctive or alternative to alpha-blockade
• Particularly useful when patient cannot tolerate phenoxybenzamine

• Blocks tyrosine hydroxylase, reduces catecholamine synthesis by 40-80%
• Used in malignant/unresectable pheo

Surgery

• Gold standard for adrenal pheo <6 cm
• Transperitoneal or retroperitoneoscopic approach
• Advantages: less pain, shorter hospital stay, faster recovery, equivalent oncological outcomes

• Large tumors (>6 cm), malignant pheo, locally invasive tumors, paragangliomas with vascular involvement
• Approaches: anterior transabdominal, posterior, flank (11th/12th rib approach)

• Continuous arterial line, central venous access, Foley catheter mandatory
• Anesthetic agents: avoid morphine, atracurium (histamine release), halothane (sensitizes myocardium)
• Use: isoflurane/sevoflurane, fentanyl, vecuronium
• Hypertensive crisis: IV Phentolamine (alpha blocker) or Sodium Nitroprusside
• Tachyarrhythmia: Esmolol or Lidocaine
• Post-removal hypotension: IV fluids, norepinephrine (if needed)

• Cortical-sparing adrenalectomy to preserve cortical function and avoid lifelong steroid replacement

Post-operative Follow-up

• 24-hour urine metanephrines or plasma metanephrines at 2-6 weeks post-op (confirm cure)
• Annual biochemical screening for recurrence (especially hereditary cases)
• Annual imaging for malignant pheo

Malignant Pheochromocytoma (10%)

• Surgery for resectable disease
• Therapeutic I-131 MIBG
• Chemotherapy: CVD protocol (Cyclophosphamide + Vincristine + Dacarbazine)
• Sunitinib, cabozantinib (tyrosine kinase inhibitors)
• Peptide receptor radionuclide therapy (PRRT) with Lu-177 DOTATATE

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Q.2 (30 Marks): Fracture Pelvis - Classification, Clinical Features, Diagnosis, Complications & Treatment

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ANATOMY - PELVIC RING

• Two innominate bones (ilium, ischium, pubis)
• Sacrum posteriorly
• Symphysis pubis anteriorly
• Strong posterior sacroiliac ligaments (most important for stability)

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CLASSIFICATION

1. Young & Burgess Classification (Mechanism-based, most widely used)

2. Tile/AO-OTA Classification (Stability-based)

3. Pennal Classification (Original mechanism-based: LC, APC, VS)

4. Fragility Fractures of Pelvis (FFP Classification - for elderly osteoporotic pelvis)

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CLINICAL FEATURES

History

• High-energy trauma: RTA, fall from height, crush injury, industrial accident
• Low-energy: in elderly - simple fall (fragility fracture)
• Inability to bear weight, severe pelvic pain

Symptoms & Signs

• Pelvic pain, tenderness over sacrum, symphysis, iliac wings
• Instability on pelvic springing test (AVOID repeated pelvic springing - increases bleeding)
• Limb length discrepancy (in VS injuries - hemipelvis migrates superiorly)
• Lower limb malrotation (external rotation in APC; internal rotation in LC)
• Skin findings: Morel-Lavallee lesion (closed degloving over greater trochanter)
• Perineal bruising (Destot's sign)
• Scrotal/labial hematoma
• Blood at urethral meatus - urethral injury (MUST check before catheterization)
• High-riding prostate on PR exam - posterior urethral rupture
• Rectal bleeding - rectal injury
• Neurological deficit - L4, L5, S1-S4 roots (from sacral fractures/SI disruption)
• Hemodynamic instability in major pelvic ring injuries

Shock

• Pelvic fractures can cause massive hemorrhage (pelvic ring capable of accommodating 3-4 liters of blood)
• Sources: venous plexus (80%) > arterial (20% - internal iliac/superior gluteal artery)

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DIAGNOSIS

Imaging

• Look for: pubic symphysis diastasis, rami fractures, sacral fractures, iliac wing fractures, SI joint disruption, leg length discrepancy
• Inlet view: AP force, anterior ring
• Outlet view: vertical displacement, sacral fractures

• Defines posterior injury (sacrum, SI joints)
• Identifies associated injuries: bladder, rectum, vascular
• 3D reconstruction for surgical planning
• Must be done in hemodynamically stable patients

• Ligamentous injuries, occult fractures, nerve root compression
• Superior for posterior ligamentous complex assessment

• Before catheterization if urethral injury suspected (blood at meatus, high-riding prostate)

• If bladder injury suspected (hematuria)

• For hemorrhage control (arterial source)

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COMPLICATIONS

Early / Immediate

1. Hemorrhagic shock - most common life-threatening complication
   • Venous: pre-sacral venous plexus
   • Arterial: superior gluteal, internal iliac arteries (APC/VS patterns)
2. Urological injuries (10-20%)
   • Posterior urethral rupture (male, membranous urethra - at apex of prostate)
   • Bladder rupture: intraperitoneal (dome rupture, requires surgery) vs extraperitoneal (conservative management with catheter)
3. Rectal/Bowel injury - open pelvic fracture (rare but high mortality)
4. Vascular injury - external iliac, femoral vessels
5. Neurological injury - lumbosacral plexus (L4-S4): foot drop, bladder/bowel dysfunction
6. Gynecological injury - vaginal tears, uterine injury

Late

1. Malunion/Non-union - pain, deformity, sitting imbalance
2. Chronic pelvic pain
3. Sexual dysfunction - impotence (pudendal nerve injury), dyspareunia
4. Bladder/Bowel dysfunction - neurogenic bladder, incontinence
5. Leg length discrepancy - from malreduced VS injury
6. Deep vein thrombosis / Pulmonary embolism - from prolonged immobility
7. Post-traumatic arthritis - acetabular fractures extending to hip joint
8. Osteomyelitis - open fractures

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TREATMENT

ATLS-based Initial Management

• Pelvic binder (circumferential sheet/SAM binder) at level of greater trochanters
  • Reduces pelvic volume, tamponades venous bleeding
  • Applied for APC (open book) injuries; NOT beneficial for LC injuries
• Aggressive IV fluid resuscitation, blood transfusion
• Massive transfusion protocol: pRBC : FFP : Platelets = 1:1:1

• For hemodynamically unstable pelvic fracture (not responding to pelvic binder + resuscitation)
• Laparotomy, retroperitoneal packing with 3 laparotomy packs per side
• Done BEFORE external fixation in damage control

• For arterial hemorrhage (identified by CT angiography)
• Embolization of internal iliac / superior gluteal arteries
• Can be combined with packing

• Damage control temporizing measure
• Anterior frame (supraacetabular pins in iliac crest)
• Stabilizes anterior ring, reduces pelvic volume

Definitive Treatment

Non-operative

• Type A (stable) fractures: Analgesia + bed rest + early mobilization
• Fragility fractures in elderly: analgesia, mobilization, osteoporosis treatment

Operative (ORIF)

• Damage control: immediate temporary stabilization
• Definitive ORIF: once patient physiologically stable (usually 3-7 days)

• Iliosacral screws (percutaneous, fluoroscopy/CT guided): Most common
  • For SI disruption, sacral fractures (Denis zone I, II)
  • Percutaneous technique: S1/S2 screws
• Posterior plate fixation (open posterior approach): for complex sacral fractures
• Spinopelvic fixation (iliac screws + lumbosacral fusion): for bilateral SI disruption (Tile C3), Denis Zone III sacral fractures (U-shaped sacral fractures) with neurological deficit

• Symphyseal plate (2-hole or 4-hole): for symphysis diastasis
• Rami fixation: retrograde or antegrade rami screws (INFIX - subcutaneous anterior pelvic fixator)

• Diverting colostomy for rectal involvement
• External fixation, wound management

• Sacral nerve root decompression for Denis Zone III fractures with S2-S4 deficit
• Laminectomy + nerve root exploration

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Q.3 (20 Marks)

Q.3.1 (10 Marks): Ileo-anal Pouch Procedure (Restorative Proctocolectomy with IPAA)

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Definition

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Indications

1. Ulcerative colitis (primary indication): medically refractory, dysplasia, carcinoma
2. Familial adenomatous polyposis (FAP): prophylactic
3. Crohn's disease is a relative contraindication (risk of pouch failure - perianal disease, small bowel involvement)

Contraindications

• Crohn's disease (relative)
• Rectal cancer (sphincter involved)
• Poor sphincter tone / incontinence
• Low rectal cancer requiring APR
• Obesity (technical difficulty)
• Patient preference/inability to comply with follow-up

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Pouch Configurations

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Surgical Steps (J-Pouch - Standard)

• Patient in Lloyd-Davies (lithotomy) position
• Midline laparotomy (or laparoscopic approach)
• Total abdominal colectomy with mesenteric division
• Proctectomy: close dissection around rectal wall (TME-like) to preserve autonomic nerves (hypogastric, pelvic nerves)
• Mucosectomy vs stapled anastomosis:
  • Stapled (preferred): leaves 1-2 cm of anal transition zone (ATZ); better functional results
  • Mucosectomy + hand-sewn anastomosis: removes all rectal mucosa; preferred in dysplasia/cancer of low rectum

• Terminal ileum folded on itself, two limbs each 15-20 cm
• Joined using linear cutting stapler (GIA) along the anti-mesenteric border (two firings)
• Apex of J = anastomotic site
• Test for tension: pouch must reach at least 4 cm below pubic symphysis without tension
• Adequacy of blood supply: marginal vessel of terminal ileum must be intact
• If tension: mobilize by dividing peritoneum of superior mesenteric vessels, right colic artery

• Stapled IPAA (most common): Circular stapler (CDH29 or EEA 28/31 mm) via transanal route
  • Stapler fired with apex of J-pouch; creates double-stapled anastomosis
  • 2 rows of staples at anastomotic level
• Hand-sewn IPAA (mucosectomy): interrupted absorbable sutures, transanal approach

• Standard of care to protect anastomosis (reduces anastomotic leak from ~10% to ~2%)
• Ileostomy loop 30-40 cm proximal to pouch
• Closed after 8-12 weeks with contrast enema confirming integrity of anastomosis

• One-stage: No ileostomy (select patients, elective, no steroids/immunosuppression, technically perfect)
• Two-stage (most common): Proctocolectomy + IPAA + loop ileostomy → ileostomy closure
• Three-stage: Subtotal colectomy + ileostomy first (emergency/unstable/high-dose steroids) → interval proctectomy + pouch → ileostomy closure

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Complications

• Anastomotic leak (2-10%) - pelvic sepsis - commonest serious complication; leads to pouch failure
• Pelvic sepsis
• Ileus / small bowel obstruction
• Bleeding

• Pouchitis (most common late complication, 40-50%): inflammation of pouch mucosa; treated with antibiotics (metronidazole, ciprofloxacin); chronic antibiotic-dependent pouchitis in ~5%
• Pouch failure (~10%): requires pouch excision and permanent ileostomy; causes: sepsis, Crohn's disease, poor function
• Cuffitis: inflammation of retained ATZ (in stapled IPAA)
• Anastomotic stricture (10-20%): treated with dilation
• Sexual dysfunction: retrograde ejaculation, dyspareunia (nerve injury during proctectomy)
• Infertility in women (reduced by laparoscopic approach)
• Floppy pouch complex: pouch prolapse/intussusception

Functional Results

• Average 4-8 bowel movements/24 hours
• 90% patients continent for gas and stool
• Good quality of life in 85-90% at 10 years
• Bailey & Love 28e states IPAA is the gold standard for UC requiring surgery

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Q.3.2 (10 Marks): Surgical Technique of Radical Nephrectomy

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Definition

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Indications

• Renal cell carcinoma (RCC) - primary treatment for T2+ tumors, or T1 not amenable to partial nephrectomy
• Large/complex renal tumors
• Renal tumors with venous thrombus (IVC involvement)
• Transitional cell carcinoma of renal pelvis (nephroureterectomy)
• Non-functioning kidney (xanthogranulomatous pyelonephritis - relative)

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Pre-operative Assessment

• CT scan abdomen (triple phase: non-contrast, arterial, venous)
• Chest CT (metastasis)
• Assessment of contralateral kidney function (GFR, nuclear scan if needed)
• Tumor staging (TNM 2017)
• IVC Doppler/CT/MRI if renal vein/IVC thrombus suspected

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Approaches

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Laparoscopic Radical Nephrectomy - Surgical Steps

• Lateral decubitus (modified flank), 45-60° rotation
• Right side: patient rolled left; left side: patient rolled right
• Kidney rest elevated, table flexed to open the flank
• Beanbag, axillary roll, padding of pressure points

• Camera port (10 mm): umbilicus
• Working port 1 (12 mm): anterior axillary line, subcostal
• Working port 2 (5 mm): mid-clavicular line, iliac crest level
• Optional assistant port: epigastric region

• Veress needle CO2 insufflation (12-15 mmHg)
• Incise the white line of Toldt to reflect colon medially
• Medial mobilization of colon and mesentery to expose retroperitoneum

• Identify ureter (medial to gonadal vein) crossing the iliac vessels
• Clip and divide ureter distally (to be removed with specimen or separately for TCC)
• Ligate gonadal vein (on left side: divide left gonadal vein at renal vein)

• Retract duodenum medially (Kocher maneuver)
• Expose inferior vena cava (IVC)
• Short right renal vein directly enters IVC - ligate with laparoscopic stapler (Endo-GIA vascular stapler) or hem-o-lok clips + scissors
• Right renal artery: lies posterior to IVC; clip and divide

• Expose aorta
• Left renal vein: longer, crosses aorta anteriorly
• Left renal artery: divide between clips BEFORE renal vein ligation (prevents congestion)
• Left gonadal vein, left adrenal vein are tributaries of left renal vein (divide both before renal vein ligation)
• Ligate left renal vein close to IVC

• Adrenalectomy indicated when:
  • Upper pole tumor
  • Tumor >7 cm
  • Adrenal involvement on imaging
  • Contiguous spread suspected
• Adrenal-sparing: lower pole tumors, normal adrenal on CT, contralateral adrenal disease
• Divide adrenal vein (right: directly to IVC; left: to left renal vein)

• Dissect entire kidney within Gerota's fascia (perinephric fat included)
• Keep Gerota's fascia intact - do not breach (violating increases local recurrence)
• Divide all remaining attachments superiorly, posteriorly, inferiorly

• Regional lymphadenectomy (hilar nodes) for staging
• Extended template (para-aortic/para-caval nodes) for N+ disease on imaging
• Limited survival benefit shown in RCTs (EORTC trial) for routine LND, but provides accurate staging

• Endoscopic bag (EntrapSack) placed around specimen
• Pfannenstiel incision or extended port site used for extraction
• Specimen sent in toto (morcellation avoided - loss of margins/staging)

• Check renal fossa, vascular stumps
• Remove ports under vision
• Fascial closure at 10/12 mm ports
• Skin closure

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Open Flank Approach (11th or 12th rib)

• Patient: lateral decubitus with flank over kidney bridge
• Incision: over 11th or 12th rib, extraperitoneal
• Rib excision or subperiosteal rib resection for access
• Gerota's fascia entered from posterior
• Steps as above (pedicle ligation, specimen removal)

IVC Thrombus Management (Level I-IV)

• Level I (renal vein only): ligated with renal vein
• Level II (infrahepatic IVC): IVC control above and below, milking thrombus
• Level III (intrahepatic): liver mobilization, hepatic vascular exclusion
• Level IV (supradiaphragmatic/intracardiac): cardiopulmonary bypass, cardiac surgery team

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Q.4 (20 Marks)

Q.4.1 (10 Marks): Energy Sources for Open and Endoscopic Surgery

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Introduction

• Electrical (electrosurgery)
• Ultrasonic
• Optical (laser)
• Plasma (argon beam, radiofrequency)

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1. ELECTROSURGERY (Diathermy)

Principles

• Uses high-frequency alternating current (300 kHz - 3 MHz) which does not stimulate cardiac muscle or cause neuromuscular excitation
• Tissue effect depends on: frequency, waveform, power, electrode size, tissue contact
• Joule heating: resistance of tissue converts electrical energy to heat
• Cell temperature 60°C: protein coagulation (hemostasis)
• Cell temperature 100°C: vaporization (cutting)
• Cell temperature >200°C: carbonization

Monopolar Electrosurgery

• Circuit: Generator → active electrode (surgical site) → patient → return electrode (dispersive pad) → generator
• Return electrode placed on large muscle mass (thigh, buttock), NOT over bony prominences or scar tissue
• Cutting mode: Pure sine wave (continuous); rapid cell heating → vaporization → cutting
• Coagulation mode: Intermittent (damped) wave; slower heating → protein coagulation
• Blend mode: Combination; adjustable
• Applications: open surgery, laparoscopy (monopolar scissors, hook)
• Risks: Stray current (insulation failure), capacitive coupling, alternate site burns, interference with pacemakers

Bipolar Electrosurgery

• Current flows between two tips of forceps only - contained; no return electrode needed
• Used near sensitive structures (nerves, vasculature)
• Precise coagulation; minimal lateral spread
• Cannot cut in standard bipolar
• Advanced bipolar (LigaSure, EnSeal): tissue fusion - seals vessels up to 7 mm

Advanced Electrosurgical Systems

• LigaSure (Medtronic): Impedance feedback system; combines pressure + bipolar RF energy; denatures collagen/elastin; vessel seal for 7 mm vessels; burst pressure 3x systolic; used extensively in laparoscopy
• EnSeal (Ethicon): Nano-composite polymer electrodes; consistent sealing

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2. ULTRASONIC ENERGY (Harmonic Scalpel)

• Ultrasonic coagulating shears (Harmonic/FOCUS/Sonicision)
• Transducer vibrates blade at 55,500 Hz (55.5 kHz)
• Mechanical energy → friction → heat → protein coagulation + tissue cutting
• Temperature: 50-100°C (much lower than electrosurgery's 150-400°C)
• No electrical current passes through patient - safe around pacemakers/ICDs
• No smoke (no carbonization at lower temperatures)
• Dual function: coagulation + cutting in one instrument
• Seals vessels up to 5 mm (Harmonic Focus: 7 mm)
• Advantages over monopolar:
  • No electrical energy, no stray current, no pacemaker interference
  • Less lateral thermal spread (< 1-2 mm at blade tip)
  • Less smoke, less char
  • One instrument for cut + coagulate
• Applications: Thyroidectomy, splenectomy, hepatectomy, laparoscopic cholecystectomy, Whipple's procedure

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3. LASER (Light Amplification by Stimulated Emission of Radiation)

Types Used in Surgery:

Properties:

• Monochromatic (single wavelength)
• Coherent (waves in phase)
• Collimated (parallel beam, minimal divergence)
• Interaction with tissue: reflection, absorption, scattering, transmission
• Safety: laser-specific goggles mandatory, fire hazard (avoid PVC/rubber in beam path)

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4. ARGON BEAM COAGULATOR (APC)

• High-frequency monopolar current conducted through ionized argon gas
• Current travels from probe to tissue via argon plasma (no electrode contact with tissue)
• Non-contact coagulation - ideal for oozing surfaces
• Eschar remains thin, flexible (superficial penetration 2-3 mm)
• Applications: liver surface hemostasis, splenorrhaphy, bronchoscopy, GI bleeding
• Risk: gas embolism if device held in contact (open vessel)

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5. RADIOFREQUENCY ABLATION (RFA)

• RF energy (450-500 kHz) delivered via needle electrode into tumor
• Ionic agitation → frictional heating → coagulative necrosis
• Applications: liver RCC, HCC, osteoid osteoma
• Electrode types: single, multiple expanding (LeVeen, RITA)

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6. MICROWAVE ABLATION (MWA)

• Electromagnetic waves (915 MHz or 2.45 GHz) → water molecule rotation → heat
• Deeper and more uniform heating than RFA; not limited by charring
• Faster (5-10 minutes vs 20-30 for RFA)
• Applications: liver metastases, HCC, lung, kidney

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7. PLASMA JET / TISSUE STABILIZATION

• PEAK PlasmaBlade: Pulsed RF plasma; precise cutting; minimal thermal damage (vs conventional monopolar)
• Used in plastic surgery, dermatology

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Comparison Table

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Q.4.2 (10 Marks): Differential Diagnosis of Solitary Thyroid Nodule

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Definition

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Differential Diagnosis

I. BENIGN CAUSES (~90-95%)

• Pure cysts (2-3%): usually benign (colloid or simple); require FNA if >1 cm
• Complex cysts: require FNA; mural nodules increase malignancy risk

• Most common cause of apparent solitary nodule
• On ultrasound: isoechoic, "spongy" appearance, comet tail artifact (colloid)
• Benign - no risk

• Benign encapsulated tumor with follicular pattern
• FNA: "follicular lesion" (Bethesda III/IV) - cannot distinguish from follicular carcinoma on cytology
• Requires hemi-thyroidectomy for histological diagnosis (capsular invasion = carcinoma)
• Types: normofollicular, macrofollicular, microfollicular, fetal, embryonal, Hurthle cell (oncocytic)

• May present as dominant nodule/lymphocytic infiltration
• Anti-TPO antibodies elevated
• Associated with slight increase in risk of papillary thyroid cancer and primary thyroid lymphoma

• Hyperfunctioning ("hot") follicular adenoma
• Autonomous thyroid function; TSH suppressed
• On radioiodine scan: "hot" nodule with suppression of rest of thyroid
• Rarely malignant (<1%)
• Treatment: radioiodine or surgery

• Rare; presents with pain, fever, tenderness
• Usually bacterial (Staphylococcus, Streptococcus)

• Painful, tender, usually follows viral illness
• Elevated ESR, low radioiodine uptake

• Thyroglossal duct cyst: midline, moves with swallowing AND tongue protrusion
• Usually in children/young adults
• Can become infected

• Inferior parathyroid adenoma may be mistaken for thyroid nodule
• Associated with hypercalcemia, hyperparathyroidism
• Distinguished by sestamibi scan, USS with FNA

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II. MALIGNANT CAUSES (~5-10%)

• Most common; young females
• "Orphan Annie eye" nuclei, nuclear grooves, intranuclear pseudoinclusions on FNA
• Psammoma bodies
• Spreads via lymphatics (cervical LN)
• Excellent prognosis (10-year survival ~98%)
• Variants: follicular variant, tall cell, columnar cell (worse prognosis)
• BRAF V600E mutation (most common, 60%)

• Middle-aged women
• FNA cannot distinguish from follicular adenoma (capsular/vascular invasion on histology)
• Spreads hematogenously (bone, lung, brain)
• Hurthle cell carcinoma (oncocytic carcinoma): variant, more aggressive
• RAS mutations, PAX8-PPAR-gamma fusion

• Arises from parafollicular C-cells (calcitonin-secreting)
• Calcitonin elevated (marker for MTC - diagnostic + follow-up)
• Amyloid deposits on histology
• 25% familial: MEN2A (MTC + pheo + parathyroid), MEN2B (MTC + pheo + marfanoid + mucosal neuromas)
• RET proto-oncogene mutation (germline in familial; somatic in sporadic)
• All patients with MTC should have genetic testing + urinary/plasma metanephrines (exclude pheo before surgery)
• Surgery: total thyroidectomy + central node dissection
• Poor response to radioiodine

• Elderly patients; rapidly enlarging, hard, fixed mass
• Most aggressive cancer (median survival 5 months)
• Symptoms: dysphagia, dysphonia, stridor, dyspnea
• Biopsy: giant cells, spindle cells, necrosis
• Rarely resectable; combined modality (surgery + chemo + RT)

• Usually diffuse large B-cell lymphoma (DLBCL)
• Arises in background of Hashimoto's thyroiditis
• Rapidly enlarging painless goiter
• Treated with chemotherapy + radiation (NOT surgery primarily)

• Kidney (RCC), lung, breast, melanoma, colon
• Usually in context of known primary

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Diagnostic Work-up of STN

Bethesda Classification (FNA):

High-risk Features on USS (ACR TIRADS):

• Hypoechoic
• Irregular margins (spiculated, lobulated)
• Taller than wide (>1 in AP)
• Microcalcifications
• Lymphadenopathy → These features prompt FNA for nodules >1 cm

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Summary Table - All Questions

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Primary Biliary Cholangitis (PBC)

Formerly: Primary Biliary Cirrhosis

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NOMENCLATURE

• Most patients diagnosed today do not progress to cirrhosis (detected early)
• The old name was stigmatizing (implied alcohol-related disease)
• The name better reflects the underlying pathology (cholangiopathy)

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DEFINITION

• Non-suppurative, inflammatory destruction of small and medium intrahepatic bile ducts
• Progressive cholestasis
• Eventual hepatic fibrosis and cirrhosis if untreated

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EPIDEMIOLOGY

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ETIOLOGY & RISK FACTORS

• HLA associations: HLA class II antigen DR8 in some populations; HLA, IL-12A, IL-12RB2 variants (interleukin-12 signaling pathway is implicated)
• Genome-wide association studies (GWAS) have confirmed multiple loci
• Concordance in monozygotic twins

• Cigarette smoking - strongly associated
• Recurrent urinary tract infections - strongly associated (molecular mimicry with E. coli antigens may trigger AMA formation)
• Toxic chemical exposure (cosmetics, hair dye, nail polish)
• Hormonal factors (estrogen exposure)

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PATHOGENESIS

Step-by-step:

• Environmental triggers (infections, chemicals) in a genetically susceptible host
• Lead to aberrant expression of "autoantigens" on bile duct epithelial cells
• Upregulation of HLA class I on hepatocytes and HLA class II on biliary epithelial cells

• The main target is the E2 component of the pyruvate dehydrogenase complex (PDC-E2) located on the inner mitochondrial membrane
• PDC-E2 is abnormally expressed on the apical surface of biliary epithelial cells in PBC patients - making them a target for immune attack
• In Sjogren syndrome co-existing with PBC, PDC-E2 is also expressed on salivary gland cells
• Antimitochondrial antibodies (AMA) directed against PDC-E2 are present in 90-95% of patients
  • Sensitivity and specificity both >95% at titer >1:40
  • AMA titers do NOT correlate with disease severity or predict treatment response
  • 5% of patients with typical PBC are AMA-negative (AMA-negative PBC)
  • ANA against nuclear pore proteins (anti-gp210) and centromeric proteins (anti-centromere) may also be present

• CD4+ and CD8+ T lymphocytes infiltrate portal tracts
• PDC-E2-specific T cells directly destroy biliary epithelial cells
• Results in ductopenia (disappearance of bile ducts from portal tracts)

• Bile duct injury → impaired bile secretion → bile acid retention
• Retained bile salts are directly hepatotoxic → secondary hepatocellular injury
• Progressive cholestasis → fibrosis → cirrhosis → liver failure

• Develops relatively early (even before cirrhosis in some patients) due to pre-sinusoidal obstruction from nodular regenerative hyperplasia
• Varices and ascites can occur without established cirrhosis (pre-cirrhotic portal hypertension)

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HISTOPATHOLOGY

Hallmark: "Florid Duct Lesion"

• Lymphoplasmacytic inflammation centered on interlobular bile ducts
• Poorly formed epithelioid granulomas in portal tracts
• Granulomatous destruction of bile duct epithelium - this is the florid duct lesion - pathognomonic of PBC
• Disease has a patchy distribution - not all portal tracts affected simultaneously

Histological Staging (Ludwig/Scheuer Classification - 4 stages):

Other features:

• Copper deposition in periportal hepatocytes (due to impaired biliary copper excretion - as in Wilson's disease histologically, but in PBC it is secondary)
• Mallory-Denk bodies in late stages
• Ductopenia (absence of bile ducts in >50% of portal tracts) - major feature of progressive disease
• Unlike obstructive/drug-induced/sepsis cholestasis: cholestasis confined to zone 3 early, then spreads to all zones

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CLINICAL FEATURES

Symptoms

• Increasingly detected incidentally via elevated ALP on routine blood tests

1. Fatigue (50%) - most common symptom
   • Can be debilitating and disproportionate to degree of liver disease
   • Unrelated to stage of disease - does not improve with treatment
   • Mechanism unclear; possibly CNS serotonergic dysfunction
2. Pruritus (30-70%)
   • Often the presenting complaint
   • May be first noticed during pregnancy but persists after delivery (unlike obstetric cholestasis)
   • Typically starts on palms/soles, progresses to generalized
   • Worse at night, in warm environments, with pressure from clothing
   • Mechanism: accumulation of pruritogens (lysophosphatidic acid, endogenous opioids, bile acids) in skin

• Vitamin D deficiency → osteomalacia, osteoporosis (metabolic bone disease - major complication; fractures)
• Vitamin K deficiency → coagulopathy
• Night blindness (Vitamin A)

1. Hyperpigmentation of skin (melanin deposition - not due to jaundice initially)
2. Sicca complex - dry eyes and dry mouth (Sjogren syndrome - overlap)

• Hepatomegaly (early)
• Splenomegaly (portal hypertension)
• Spider naevi, palmar erythema (late)
• Features of portal hypertension: ascites, varices, caput medusae
• Kayser-Fleischer rings are NOT present (helps exclude Wilson's disease)

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ASSOCIATED CONDITIONS / EXTRAHEPATIC MANIFESTATIONS

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DIAGNOSIS

Laboratory Investigations

Imaging

• Ultrasound abdomen: First-line
  • Normal bile ducts (no dilation)
  • Confirms absence of extrahepatic biliary obstruction
  • May show hepatosplenomegaly, ascites in advanced disease
  • Cholangiogram (MRCP/ERCP) is NORMAL (large ducts unaffected) - key difference from PSC
• CT scan / MRI: to exclude biliary obstruction, HCC surveillance

Liver Biopsy

• Not required for diagnosis when cholestatic LFTs + positive AMA (both >95% sensitivity and specificity together)
• Indicated when:
  • AMA-negative PBC (5%)

  • 2x ULN aminotransferase elevation (to exclude overlap syndrome)

  • Staging of disease
  • Discordant clinical/biochemical features
• Diagnostic if florid duct lesion present

Diagnostic Criteria (EASL/AASLD):

1. Cholestatic biochemistry (elevated ALP + GGT)
2. Positive AMA ≥1:40 (or AMA-M2 positive)
3. Histological changes consistent with PBC on liver biopsy

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NATURAL HISTORY & PROGNOSIS

• Slowly progressive over decades (average time from diagnosis to death: 22 years untreated)
• Asymptomatic patients: ~50% remain asymptomatic for up to 10 years
• Symptomatic patients: median survival ~10-12 years (historical, pre-UDCA era)
• Rising bilirubin is the single most important prognostic indicator
• Two pathways to end-stage:
  1. Progressive duct loss → widespread cholestasis → cirrhosis → liver failure
  2. Portal hypertension before established cirrhosis

Mayo Risk Score (prognostic model):

• Used to time liver transplantation

Risk of HCC:

• Relative risk significantly elevated, especially in men with cirrhotic PBC
• Annual HCC surveillance with USS ± AFP recommended in cirrhotic patients

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TREATMENT

1. URSODEOXYCHOLIC ACID (UDCA) - First-line

• Dose: 13-15 mg/kg/day (divided or single daily dose)
• Mechanism: Replaces toxic hydrophobic bile acids in the bile acid pool; enters enterohepatic circulation → reduces bile acid toxicity; also has anti-apoptotic, immunomodulatory effects
• Under normal physiology, UDCA accounts for 4% of total bile acids; treatment raises it to 40-60%
• Biochemical effects: Improves ALP, GGT, bilirubin, cholesterol, aminotransferases
• Clinical effects:
  • Slows disease progression
  • Delays time to transplantation
  • Improves histological staging (less fibrosis progression)
  • Reduces risk of esophageal varices
  • Does NOT improve fatigue
  • Variable effect on pruritus
• Response criteria (Barcelona/Paris criteria): ALP <3x ULN AND AST <2x ULN AND bilirubin normal after 1 year of UDCA
• ~30-40% of patients are inadequate responders - need second-line therapy

2. OBETICHOLIC ACID (OCA) - Second-line

• Dose: 5-10 mg/day (titrated based on response and tolerability)
• Mechanism: Highly selective Farnesoid X Receptor (FXR) agonist (semi-synthetic hydrophobic bile acid derivative)
  • FXR regulates genes involved in bile acid synthesis, secretion, absorption, and detoxification
  • Activating FXR reduces bile acid synthesis (via FGF19/FGFR4 signaling)
• Indication: UDCA inadequate responders (ALP >1.67x ULN and/or total bilirubin <2x ULN after ≥12 months of UDCA)
• Phase 3 trial (POISE): OCA 5-10 mg + UDCA → 46-47% biochemical response vs 5% with placebo
• Side effect: PRURITUS - occurs in up to 68%; 10% require discontinuation
• Caution: Dose adjustment required in advanced liver disease (Child-Pugh B/C) - risk of hepatic decompensation
• Effect on clinical outcomes (transplant-free survival) not yet definitively established

3. BEZAFIBRATE (Fibrate) - Second-line/adjunctive

• Mechanism: PPAR-alpha agonist → reduces bile acid synthesis, immunomodulation
• Evidence: Bezafibrate 400 mg/day improves liver chemistry tests in UDCA non-responders
• BEZURSO trial (2018): bezafibrate significantly improved ALP normalization vs placebo
• Well tolerated; less pruritus than OCA

4. MANAGEMENT OF SYMPTOMS

• First-line: Cholestyramine (anion exchange resin, bile acid binder) 4 g before meals; must be separated from other medications by 4 hours (binds drugs)
• Second-line: Rifampicin 150-300 mg BD - induces cytochrome P450 enzymes; hepatotoxic in ~5% - monitor LFTs
• Third-line: Naltrexone / Naloxone (opioid antagonist) - reversal of endogenous opioid-mediated itch; may cause opioid withdrawal symptoms
• Fourth-line: Sertraline (SSRI) - some evidence
• Linerixibat (IBAT inhibitor): Novel; inhibits ileal bile acid transporter → reduces bile acid reabsorption; promising in trials
• Liver transplantation if refractory pruritus

• No specific treatment effective
• Exclude reversible causes: anemia, hypothyroidism, depression, sleep disorder
• Modafinil: limited evidence

• Calcium 1000-1500 mg/day + Vitamin D 400-800 IU/day supplementation
• Bisphosphonates (alendronate, risedronate) for established osteoporosis
• DEXA scan every 2-3 years
• Vitamin D levels monitoring

• Fat-soluble vitamins (A, D, E, K) supplementation
• Low-fat diet; medium-chain triglycerides (MCT)
• Pancreatin supplementation if severe

• Paradoxically, despite high cholesterol, cardiovascular risk is not substantially elevated in early PBC (lipoprotein X - anti-atherogenic)
• Statins relatively safe but with caution in liver disease
• In later disease with low albumin, dyslipidemia becomes pro-atherogenic

• Variceal screening: endoscopy at diagnosis
• Non-selective beta-blockers (propranolol, carvedilol) for prophylaxis
• Banding for bleeding varices
• Ascites: salt restriction, diuretics (spironolactone ± furosemide)
• TIPS for refractory portal hypertension

5. LIVER TRANSPLANTATION - Definitive treatment

• Indications:
  • End-stage liver disease (cirrhosis with decompensation)
  • Mayo Risk Score >7.8
  • Intractable pruritus (unresponsive to all medical treatment)
  • Recurrent variceal bleeding
  • Spontaneous bacterial peritonitis
  • Hepatic encephalopathy
  • Bilirubin >6 mg/dL (>103 µmol/L)
• Outcomes: Excellent 5-year survival (~85%); better than most other indications for transplant
• Recurrence of PBC in the graft: Occurs in 20-30% by 10 years; usually mild and treated with UDCA

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PBC vs PSC - Key Comparison

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COMPLICATIONS

1. Cirrhosis and liver failure - end-stage disease
2. Portal hypertension - varices, ascites, encephalopathy
3. Osteoporosis / Osteomalacia - from Vitamin D malabsorption (major morbidity)
4. HCC - relative risk significantly increased (especially in men, cirrhotic stage)
5. Hyperlipidemia - xanthomas, xanthelasmas
6. Coagulopathy - Vitamin K malabsorption
7. Hypothyroidism - associated autoimmune thyroid disease
8. Bacterial cholangitis - uncommon (unlike PSC)
9. Glomerulonephritis - membranous nephropathy (rare)

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SUMMARY DIAGRAM

Genetic susceptibility (HLA, IL-12 axis)
         +
Environmental trigger (UTI, smoking, chemicals)
         ↓
PDC-E2 expressed on biliary epithelial cells
         ↓
T cell attack + AMA (anti-PDC-E2) production
         ↓
Florid duct lesion → Ductopenia
         ↓
Bile acid retention → Hepatocellular injury
         ↓
Cholestasis → Fibrosis → Cirrhosis → Portal HTN → Liver Failure

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Recent evidence update (PMID 39720853 - Liver International 2025): A systematic review with network meta-analysis confirms that second-line treatments after UDCA failure (obeticholic acid and bezafibrate) significantly improve biochemical markers. Combination therapy (UDCA + bezafibrate) shows strong evidence as the preferred second-line regimen in many guidelines, with favorable safety compared to OCA. A 2026 Spanish practice guideline (PMID 41232665) now recommends bezafibrate as an evidence-based second-line option alongside OCA.