General Surgery Four-Station OSCE: General Structure The four-station General Surgery OSCE is designed around the sequential stages of clinical patient management and aims to assess students’ medical knowledge, clinical reasoning, and decision-making skills. Each station represents an independent yet interconnected phase of patient care, reflecting authentic clinical practice. Station 1 – Initial Assessment The student performs the initial assessment of the patient, identifies and prioritizes the presenting problems, evaluates the patient’s overall condition, and applies an appropriate clinical assessment algorithm when indicated (e.g., the ABCDE approach). Assessment focuses on the student’s systematic approach, patient safety, and ability to establish appropriate clinical priorities. Station 2 – Clinical Assessment and Diagnostic Reasoning The student analyzes the provided clinical information, interprets physical examination findings and relevant laboratory and/or imaging results, formulates the most likely diagnosis, or assesses the severity of the patient’s condition. This station evaluates clinical reasoning, diagnostic accuracy, and the integration of clinical data. Station 3 – Recognition of Critical Findings The student identifies clinical findings that pose an immediate threat to life or organ function, assesses the patient’s level of risk, recognizes urgent clinical problems, and prioritizes appropriate interventions. This station evaluates the ability to recognize critical conditions and respond according to clinical urgency. Station 4 – Management Plan and Clinical Decision-Making The student develops an evidence-based initial management plan, justifies clinical decisions, determines the need for additional investigations, specialist consultation, hospitalization, or transfer to a higher-level or specialized care facility, and outlines the subsequent management strategy. This station assesses sound clinical judgment, adherence to evidence-based practice, and appropriate planning of patient care. Using this framework, generate high yield information with these topics in mind. SURGERY - Shock and Blood Transfusion Abdominal Trauma Wounds, Tissue Repair Surgical Infection Nutrition and Fluid Therapy Chest Injuries Anesthesia and Pain Management Burns Basic Surgical Skills and Anastomosis Arterial Disorders

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Here is the complete high-yield General Surgery OSCE guide, organized by topic with all four stations mapped to each. This draws on Sabiston, Schwartz, Fischer's Mastery, Tintinalli, Miller's Anesthesia, and Goldman-Cecil, integrated with core clinical practice.

General Surgery Four-Station OSCE: High-Yield Reference Guide

TOPIC 1 - SHOCK AND BLOOD TRANSFUSION

Station 1 - Initial Assessment

ABCDE priorities:

Airway/Breathing: Ensure patent airway; apply high-flow O2 (15 L/min NRB mask)
Circulation: Assess HR, BP, capillary refill, skin color/temperature, JVP, urine output
Disability: GCS, pupils
Exposure: Full undress; look for obvious hemorrhage, signs of concealed bleeding

Key clinical flags suggesting shock:

HR >100, SBP <90 mmHg, RR >20, UO <0.5 mL/kg/hr
Cold, clammy skin; altered consciousness; thready pulse

Immediate life-saving steps:

Large-bore IV access (two 16G antecubital lines)
Bloods: FBC, U&E, LFT, coagulation, group & crossmatch, ABG, lactate
IV fluid bolus (cautious in cardiogenic/obstructive shock)

Station 2 - Clinical Assessment and Diagnostic Reasoning

ATLS Classification of Hemorrhagic Shock:

Class	Blood Loss	HR	SBP	RR	UO (mL/hr)	CNS
I	<750 mL (<15%)	<100	Normal	14-20	>30	Normal
II	750-1500 mL (15-30%)	100-120	Normal	20-30	20-30	Anxious
III	1500-2000 mL (30-40%)	120-140	Decreased	30-40	5-15	Confused
IV	>2000 mL (>40%)	>140	Very low	>35	<5	Lethargic/unconscious

Types of shock - key differentiators:

Type	Preload	CO	SVR	Example
Hypovolemic	Low	Low	High	Hemorrhage
Cardiogenic	High	Low	High	MI, tamponade
Distributive (septic)	Low	High	Low	Sepsis
Obstructive	Low	Low	High	Tension pneumo, PE

Bedside markers of resuscitation adequacy: Lactate clearance (>10% per hour), UO, base deficit normalization

Station 3 - Recognition of Critical Findings

Red flags requiring immediate action:

Class III/IV shock: initiate massive transfusion protocol (MTP)
Massive Transfusion Protocol (MTP): Activate when >10 units pRBC anticipated in 24h OR >3 units in 1h
Ratio: pRBC : FFP : Platelets = 1:1:1 (damage control resuscitation)
Tension pneumothorax: immediate needle decompression (2nd ICS MCL) + chest drain
Cardiac tamponade (Beck's triad: JVD, muffled heart sounds, hypotension): pericardiocentesis
Pulseless electrical activity (PEA) - consider 4H/4T reversible causes

Transfusion triggers (evidence-based):

Hb <7 g/dL in stable patients (restrictive strategy reduces complications)
Hb <8-10 g/dL in active hemorrhage, ACS, or poor cardiopulmonary reserve
Hb <10 g/dL if symptomatic (chest pain, dyspnea)

Station 4 - Management Plan

Resuscitation endpoints: Lactate <2, pH >7.35, BE <-2, UO >0.5 mL/kg/hr, normothermia

Damage Control Resuscitation (DCR) principles:

Permissive hypotension (SBP 80-90 mmHg until hemorrhage controlled) - except TBI
1:1:1 blood product ratio
Tranexamic acid (TXA): 1g IV over 10 min within 3 hours of injury, then 1g over 8h (CRASH-2 trial)
Avoid crystalloid excess (dilutional coagulopathy, abdominal compartment syndrome)
Calcium supplementation with massive transfusion (citrate chelates Ca2+)
Warm all fluids; warming blankets (lethal triad: hypothermia + coagulopathy + acidosis)

Transfusion complications:

Acute hemolytic reaction: ABO mismatch - STOP transfusion immediately, fluids, diuretics, monitor renal function
TRALI: Respiratory distress within 6h - supportive, discontinue
TACO: Circulatory overload - diuretics, slowing rate
Febrile non-hemolytic: Most common - premedicate with paracetamol
Transfusion-associated sepsis: Culture, broad-spectrum antibiotics

TOPIC 2 - ABDOMINAL TRAUMA

Station 1 - Initial Assessment

ATLS Primary Survey (ABCDE):

All trauma patients: C-spine immobilization until cleared
Exposure: log roll, inspect back and perineum
Key exam: abdominal guarding, rigidity, distension, seat belt sign, ecchymosis

Mechanism-based suspicion:

Blunt (MVA, fall): solid organ injury (spleen, liver most common), mesentery, retroperitoneum
Penetrating stab: hollow viscus > solid organ
Penetrating gunshot: mandatory exploration (high kinetic energy)
Seat belt sign + lumbar pain: Chance fracture + bowel injury until proven otherwise

Station 2 - Clinical Assessment and Diagnostic Reasoning

Investigations:

FAST Exam (Focused Assessment with Sonography for Trauma):

4 windows: pericardial, hepatorenal (Morison's pouch), splenorenal, pelvic (pouch of Douglas)
Detects free intraperitoneal fluid
Sensitivity ~80% for hemoperitoneum; limited for retroperitoneum and hollow viscus
Extended FAST (eFAST): adds bilateral lung fields for pneumo/hemothorax

CT Abdomen/Pelvis with contrast:

Gold standard for stable patients
Grades solid organ injuries (AAST grading I-V)
Identifies active extravasation (blush = arterial bleeding)

Diagnostic Peritoneal Lavage (DPL):

Largely replaced by FAST/CT but role in unstable patient with equivocal FAST
Positive: >100,000 RBC/mm3 (blunt), >10,000 (penetrating)

Spleen injury grading (AAST):

Grade I: subcapsular hematoma <10%
Grade III: >50% hematoma or laceration >3cm
Grade IV/V: hilar injury or shattered spleen

Station 3 - Recognition of Critical Findings

Immediate surgical indications (laparotomy):

Hemodynamic instability + positive FAST
Peritonitis on exam
Evisceration
Gunshot wound crossing midline
Positive DPL (gross blood/succus)
Diaphragmatic injury on CXR

Life-threatening injuries not to miss:

Splenic rupture: most common organ injured in blunt trauma; delayed rupture up to 2 weeks
Liver laceration: right lobe most common; Pringle maneuver to control hepatic inflow
Mesenteric tear: bowel ischemia risk
Duodenal hematoma: in children/handlebar injury - retroperitoneal, seen on CT
Bladder rupture: gross hematuria + pelvic fracture - cystogram required

Station 4 - Management Plan

Decision algorithm:

Hemodynamically unstable + positive FAST → Emergency laparotomy
Hemodynamically stable → CT scan → manage by injury grade

Non-operative management (NOM): Standard for grades I-III solid organ injuries in stable patients; requires ICU monitoring, serial exams, serial Hb

Angioembolization: Arterial blush on CT in stable patient (grades III-IV); interventional radiology

Damage Control Surgery (DCS):

Stage 1: Abbreviated laparotomy - control hemorrhage and contamination (pack, ligate)
Stage 2: ICU resuscitation (48-72h)
Stage 3: Definitive repair

Specific injuries:

Splenic grade V or failed NOM: splenectomy + post-splenectomy vaccines (pneumococcal, meningococcal, Hib)
Liver - Pringle maneuver (hepatoduodenal ligament compression), damage control packing
Bladder rupture: intraperitoneal = surgical repair; extraperitoneal = catheter drainage alone

TOPIC 3 - WOUNDS AND TISSUE REPAIR

Station 1 - Initial Assessment

Wound assessment framework:

Mechanism: laceration, crush, avulsion, bite, puncture, gunshot
Contamination: clean/clean-contaminated/contaminated/dirty-infected
Time since injury (golden period: <6-8h for primary closure)
Tetanus status
Neurovascular status distal to wound
Bone/tendon involvement

Surgical wound classification:

Class I (Clean): elective, no breach of GI/GU/respiratory - SSI rate 1-2%
Class II (Clean-contaminated): controlled opening of hollow viscus - SSI 5-10%
Class III (Contaminated): open traumatic, gross spillage - SSI 10-15%
Class IV (Dirty/Infected): established infection, perforated viscus - SSI >40%

Station 2 - Clinical Assessment and Diagnostic Reasoning

Phases of wound healing:

Hemostasis (0-12h): vasoconstriction, platelet plug, clot formation
Inflammatory (1-5 days): neutrophils (1-2d), then macrophages (day 3); cardinal signs of inflammation; phagocytosis
Proliferative (5 days - 3 weeks): fibroblast migration and collagen synthesis (type III initially), angiogenesis (granulation tissue), epithelialization, wound contraction (myofibroblasts)
Remodeling (3 weeks - 2 years): type III collagen replaced by type I; maximum tensile strength 80% of original at 6 weeks; scar maturation

Key molecular mediators:

PDGF: fibroblast recruitment
TGF-β: collagen synthesis, scar formation
VEGF: angiogenesis
EGF: epithelialization

Wound closure options:

Primary intention (1° closure): immediate closure - minimal scarring
Secondary intention: wound left open, heals by granulation and contraction - irregular wounds/infected
Delayed primary (tertiary/3°): closure at 4-5 days after contaminated wound clears

Station 3 - Recognition of Critical Findings

Wound complications requiring urgent action:

Complication	Timing	Key Features	Action
Wound dehiscence	Day 5-8	"popping" sensation, serosanguinous drainage	Pack, saline dressing, OR if evisceration
Evisceration	Day 5-8	Bowel through wound	Moist saline dressing, emergency surgery
SSI - superficial	5-7 days	Rubor, calor, dolor, pus	Open, clean, pack
SSI - deep/fascial	Variable	Fever, induration, systemic sepsis	Surgical exploration
Necrotizing fasciitis	Any	Disproportionate pain, dishwater fluid, gas on imaging, rapid spread	Emergency surgery within 6h + broad-spectrum antibiotics
Keloid	Weeks-months	Grows beyond wound margins, does not regress	Steroid injection, surgical excision + radiation

Necrotizing fasciitis LRINEC score (Laboratory Risk Indicator for NF):

CRP >150: +4
WBC 15-25: +1; >25: +2
Hb 11-13.5: +1; <11: +2
Na <135: +2
Creatinine >141: +2
Glucose >10: +1
Score >6: high suspicion; >8: strongly consider NF

Station 4 - Management Plan

Wound management principles:

Irrigation: high-pressure saline irrigation (3-8 PSI) reduces bacterial load
Debridement: sharp excision of non-viable tissue
Hemostasis: pressure, electrocautery, suture ligation

Suture selection guide:

Tissue	Suture type	Material
Fascia/tendon	Delayed absorbable	PDS (polydioxanone)
Deep subcutaneous	Absorbable	Vicryl (polyglactin)
Skin	Non-absorbable	Nylon/prolene
Bowel anastomosis	Absorbable	PDS or Vicryl
Vascular	Non-absorbable	Prolene

Tetanus prophylaxis:

Clean wound + up-to-date (≤5y): nothing
Clean wound + >10y or unknown: Td booster
Dirty wound + >5y: Td booster
Dirty wound + unknown/never: Td + TIG (tetanus immune globulin)

Negative pressure wound therapy (NPWT/VAC): Applied to large wounds; promotes granulation, reduces edema, facilitates closure

TOPIC 4 - SURGICAL INFECTION

Station 1 - Initial Assessment

Sepsis screening (Sepsis-3 criteria):

SIRS (≥2): Temp >38 or <36°C, HR >90, RR >20 or PaCO2 <32, WBC >12 or <4
Sepsis: suspected infection + SOFA score increase ≥2
Septic shock: sepsis + vasopressor requirement to maintain MAP ≥65 + lactate >2 mmol/L

qSOFA (bedside screening): ≥2 of: altered mentation, RR ≥22, SBP ≤100

Surgical infection types:

SSI (superficial/deep incisional/organ-space)
Intraabdominal abscess
Necrotizing soft tissue infection (NSTI)
Clostridial myonecrosis (gas gangrene)
Anastomotic leak

Station 2 - Clinical Assessment and Diagnostic Reasoning

Infection severity markers:

WBC with differential (left shift = band forms)
CRP, procalcitonin (PCT >0.5 suggests bacterial; >2 suggests sepsis)
Lactate >2 mmol/L = sepsis; >4 = septic shock
Blood cultures x2 (before antibiotics)
Imaging: USS/CT for abscess localization; CT showing gas in soft tissue = NF

Common causative organisms:

Infection	Organism
SSI (clean)	Staph aureus, coagulase-negative Staph
Intraabdominal	E. coli, Bacteroides fragilis, Enterococcus
NF Type I (polymicrobial)	Mixed aerobes + anaerobes
NF Type II	Group A Strep (GAS)
Clostridial myonecrosis	Clostridium perfringens
Biliary	E. coli, Klebsiella, Enterococcus

Station 3 - Recognition of Critical Findings

Surgical emergencies in infection:

Necrotizing fasciitis: disproportionate pain, "wooden" induration, dusky/necrotic skin, crepitus, systemic sepsis - emergency debridement within 6h, mortality increases 9x with each 24h delay
Clostridial gas gangrene: bronze discoloration, crepitus, "mousy/sweet" odor, rapid systemic toxicity - emergency radical debridement/amputation
Fournier's gangrene: NF of perineum/scrotum - colostomy + debridement
Anastomotic leak: fever, abdominal pain, ileus, drain output change (day 3-7 postop) - CT confirms, management: return to OR or CT-guided drainage

Signs of inadequate source control: Persistent fever despite antibiotics; rising CRP/procalcitonin; clinical deterioration

Station 4 - Management Plan

Surviving Sepsis Bundle (1-hour):

Measure lactate; re-measure if >2
Blood cultures x2 before antibiotics
Broad-spectrum antibiotics within 1 hour
30 mL/kg crystalloid for hypotension or lactate ≥4
Vasopressors if MAP <65 despite resuscitation (norepinephrine first-line)

Surgical source control: Within 6-12h when indicated (abscess drainage, perforation closure, NF debridement)

Antibiotic approach:

Community intraabdominal: ceftriaxone + metronidazole, or co-amoxiclav
Hospital-acquired/severe: piperacillin-tazobactam or carbapenem
NF: piperacillin-tazobactam + clindamycin (toxin inhibition) + vancomycin (MRSA coverage)
De-escalate based on cultures at 48-72h; target 4-7 days for adequate source control

SSI prevention bundle: Weight-based prophylaxis within 60 min of incision, redose if >2 half-lives, maintain normothermia, glycemic control (<10 mmol/L), clippers not razors

TOPIC 5 - NUTRITION AND FLUID THERAPY

Station 1 - Initial Assessment

Fluid status assessment:

Hydration: skin turgor, mucous membranes, axillary moisture, sunken eyes
Volume: JVP, HR, BP (postural drop), capillary refill, UO
Fluid losses: drain output, ileus, fever, vomiting, surgical losses
Daily requirements: Water 30-35 mL/kg, Na+ 1-2 mmol/kg, K+ 1 mmol/kg

Nutritional risk screening:

NRS-2002 or MUST score for surgical patients
Markers of malnutrition: albumin <30 g/L, pre-albumin <15 mg/dL, BMI <18.5
Recent unintentional weight loss >10% in 6 months = significant

Station 2 - Clinical Assessment and Diagnostic Reasoning

Fluid compartments:

Total body water: 60% body weight (men); 50% (women)
Intracellular fluid (ICF): 2/3 TBW
Extracellular fluid (ECF): 1/3 TBW (interstitial 3/4, plasma 1/4)

IV fluid selection:

Fluid	Na	Cl	K	Cal	Use
Normal saline (0.9%)	154	154	0	-	Volume replacement, hyponatremia
Hartmann's/LR	131	111	5	-	Maintenance, trauma, surgical
Dextrose 5%	-	-	-	200	Free water replacement, hypernatremia
D5W + 0.45% NaCl	77	77	-	100	Hypotonic maintenance
Colloid (albumin)	-	-	-	-	Oncotic pressure, hypoalbuminemia

Electrolyte disturbances postop:

Hyponatremia: excess hypotonic fluid/SIADH postop - fluid restrict, treat cause
Hypokalemia: common postop (ileus, NG losses) - replace K+ cautiously
Hyperkalemia: renal failure, tissue destruction - ECG, treat if >6.5 mmol/L

Station 3 - Recognition of Critical Findings

Fluid emergencies:

Hypovolemic shock: Class III/IV - immediate resuscitation (see Topic 1)
Abdominal compartment syndrome (ACS): bladder pressure >20 mmHg + new organ dysfunction; occurs after massive resuscitation - decompressive laparotomy
Refeeding syndrome: occurs within 72h of re-introducing nutrition in malnourished patients; severe hypophosphatemia + hypokalemia + hypomagnesemia leading to cardiac arrhythmia, respiratory failure, seizures
- Prevention: start nutrition slowly (10 kcal/kg/day); supplement phosphate, K+, Mg2+, thiamine before feeding

Nutritional deficiency warning:

Vitamin C deficiency: impaired collagen synthesis, wound dehiscence
Zinc deficiency: poor wound healing, immune dysfunction
Thiamine: essential before glucose in malnourished/alcohol patients (Wernicke's prevention)

Station 4 - Management Plan

Perioperative fluid strategy:

Goal-directed fluid therapy (GDFT): guided by cardiac output monitoring, stroke volume variation
Avoid: both hypovolemia (tissue hypoperfusion) and fluid overload (edema, anastomotic leak, ACS)
Enhanced Recovery After Surgery (ERAS): restrict preoperative fasting to 6h solids/2h clear fluids; carbohydrate loading

Nutritional support algorithm:

GI tract functional? → Yes → Enteral nutrition (EN) preferred
EN route: oral supplements → NG tube → NJ tube (if gastroparesis) → PEG (long-term)
GI tract non-functional (ileus, fistula, short bowel) → Parenteral nutrition (TPN/PN)

TPN composition and monitoring:

Macros: 25-35 kcal/kg/day; protein 1.2-2.0 g/kg/day; 30-40% fat
Glucose <180 mg/dL perioperatively (insulin sliding scale)
Monitor: daily electrolytes, weekly LFTs, triglycerides, trace elements
TPN complications: line sepsis (CLABSI), cholestasis, refeeding syndrome, hyperglycemia

When to start nutrition:

Enteral: within 24-48h of major surgery if hemodynamically stable
Critical care: within 24-48h of ICU admission
TPN: if EN not achievable by day 3-7

TOPIC 6 - CHEST INJURIES

Station 1 - Initial Assessment

Primary survey - immediately life-threatening chest injuries (ATLS "Deadly Six"):

Must be identified and treated during primary survey:

Tension pneumothorax - tracheal deviation (away from side), absent breath sounds, JVD, hypotension
Open pneumothorax (sucking chest wound)
Massive hemothorax (>1500 mL blood in pleural space)
Flail chest (paradoxical movement)
Cardiac tamponade (Beck's triad)
Airway obstruction

Potentially life-threatening (secondary survey):

Simple pneumothorax, hemothorax
Pulmonary contusion
Aortic disruption
Tracheobronchial injury
Esophageal injury
Diaphragmatic rupture
Myocardial contusion

Station 2 - Clinical Assessment and Diagnostic Reasoning

Key imaging:

CXR findings:

Tension pneumothorax: absent lung markings, tracheal deviation, mediastinal shift, hemidiaphragm depression
Hemothorax: opacification (>200 mL visible on CXR)
Rib fractures: first rib fracture = high-energy injury (subclavian vessels, brachial plexus)
Flail chest: multiple adjacent rib fractures (≥3 ribs in ≥2 places)
Widened mediastinum (>8cm): aortic injury until proven otherwise → CT angiography

Arterial blood gas:

Type I respiratory failure (hypoxemia) vs. Type II (hypercapnia + hypoxemia)
ETCO2 monitoring in ventilated patients

Rib fracture severity: Each rib fracture increases pneumonia risk by 27%, mortality by 19% (elderly)

Station 3 - Recognition of Critical Findings

Immediate interventions:

Condition	Diagnosis	Immediate Treatment
Tension pneumothorax	Clinical (do NOT wait for CXR)	Needle decompression: 2nd ICS MCL; then chest drain 5th ICS AAL
Open pneumothorax	Sucking wound	3-sided occlusive dressing; then chest drain remote from wound
Massive hemothorax	CXR/clinical	Large-bore (32-36Fr) chest drain; autotransfusion if available; surgery if >1500 mL initial or >200 mL/h x3h
Cardiac tamponade	Beck's triad, FAST	Pericardiocentesis/pericardial window; thoracotomy
Flail chest	Paradoxical movement	O2, analgesia, positive pressure ventilation (if failing)
Traumatic aortic rupture	Widened mediastinum + mechanism	CT angiography; TEVAR (thoracic endovascular aortic repair)

Station 4 - Management Plan

Chest drain (tube thoracostomy):

Position: 5th ICS, anterior axillary line ("safe triangle")
Size: 28-32Fr for pneumothorax; 32-36Fr for hemothorax
Connect to underwater seal drain
Removal criteria: no air leak x24h, drainage <200 mL/24h, lung re-expanded

Analgesia for rib fractures (critical for preventing complications):

Multimodal: paracetamol + NSAIDs + opioid PRN
Regional: thoracic epidural (gold standard), serratus anterior plane block, intercostal nerve blocks
Incentive spirometry, physiotherapy
Consider rib fixation surgery in flail chest with respiratory failure

Pulmonary contusion management:

O2 supplementation, lung-protective ventilation (tidal volume 6 mL/kg IBW)
Fluid restriction to avoid pulmonary edema
Expect worsening over 24-48h before improvement

Indications for thoracotomy:

Penetrating cardiac injury
Massive hemothorax (>1500 mL initial or >200 mL/h x3h)
Emergency department resuscitative thoracotomy (penetrating trauma with witnessed arrest)

TOPIC 7 - ANESTHESIA AND PAIN MANAGEMENT

Station 1 - Initial Assessment

Pre-anesthetic assessment:

ASA classification (I-VI): I = healthy; II = mild systemic disease; III = severe; IV = life-threatening; V = moribund; VI = brain dead
Airway assessment: LEMON mnemonic
- L = Look (obesity, beard, short neck)
- E = Evaluate (3-3-2 rule: 3 finger mouth opening, 3 finger hyoid-mental, 2 finger thyromental)
- M = Mallampati (I-IV)
- O = Obstruction
- N = Neck mobility
Mallampati I-II = easy intubation; III-IV = potentially difficult
History: allergies (latex, antibiotics), medications, prior anesthesia problems, fasting status (NPO)

Fasting guidelines: 6h solids, 4h breast milk, 2h clear fluids (6-4-2 rule)

Station 2 - Clinical Assessment and Diagnostic Reasoning

Types of anesthesia:

Type	Mechanism	Agents	Use
General (GA)	Loss of consciousness	Propofol, thiopental (induction); isoflurane, sevoflurane (maintenance)	Major surgery
Regional - spinal	Intrathecal LA	Bupivacaine 0.5% heavy	Lower limb, perineum, hernia
Regional - epidural	Epidural space	Bupivacaine + fentanyl	Major abdo/thoracic, labor
Regional - nerve block	Peripheral nerve	Bupivacaine, ropivacaine	Limb surgery
Local (LA)	Nerve membrane stabilization	Lidocaine, bupivacaine	Minor surgery

Local anesthetic toxicity (LAST):

CNS: perioral tingling, tinnitus, seizures
CVS: arrhythmia, cardiovascular collapse
Maximum doses: Lidocaine 3 mg/kg plain, 7 mg/kg with adrenaline; Bupivacaine 2 mg/kg
Treatment: stop LA, 100% O2, seizure control, 20% intralipid emulsion IV (1.5 mL/kg bolus)

Spinal vs. epidural:

Spinal: single injection, faster onset, denser block, post-dural puncture headache risk
Epidural: catheter, adjustable, longer duration, larger volumes needed

Station 3 - Recognition of Critical Findings

Anesthetic emergencies:

Emergency	Features	Immediate Action
Malignant hyperthermia	Hyperthermia, masseter spasm, tachycardia, hypercapnia, rigidity, dark urine	Stop all trigger agents (suxamethonium, volatile), dantrolene 2.5 mg/kg IV, cooling, bicarbonate
Failed intubation	Cannot intubate, cannot oxygenate (CICO)	Front-of-neck access (cricothyroidotomy)
Anaphylaxis	Urticaria, bronchospasm, hypotension	Stop trigger, adrenaline 0.5 mg IM, fluids, steroids, antihistamines
High spinal	Hypotension, bradycardia, apnea, loss of consciousness	Vasopressors, atropine, intubate
LA toxicity	CNS/CVS signs	20% intralipid, CPR if arrest
Awareness under GA	Recall of intraoperative events	Deepen anesthesia, BIS monitoring, psychological support postop

Post-op respiratory depression: Opioid overdose - naloxone 0.4 mg IV in 0.1 mg increments

Station 4 - Management Plan

WHO Analgesic Ladder (surgical adaptation):

Non-opioid: paracetamol 1g QID + NSAIDs (ibuprofen/diclofenac)
Weak opioid: tramadol, codeine
Strong opioid: morphine, oxycodone, fentanyl
Invasive: epidural, nerve block, IV PCA

Multimodal analgesia (ERAS principle): Combining agents at different receptor levels reduces opioid consumption by 30-50%

Paracetamol + NSAID + gabapentinoid (pregabalin/gabapentin) + opioid PRN + regional technique

PCA (Patient-Controlled Analgesia):

Morphine: 1 mg bolus, 5 min lockout
Advantages: patient empowerment, fewer overdoses, better pain control

Regional analgesia superiority:

Epidural: best for thoracic, upper abdominal, hip/knee
TAP block: postop abdominal analgesia
Femoral/adductor canal block: knee surgery
Brachial plexus block: upper limb

PONV (Postoperative nausea and vomiting):

Apfel score: female, non-smoker, PONV history, opioid use (each = 1 point)
Score 0-1: low risk; 2: 40%; 3: 60%; 4: 80%
Prophylaxis: ondansetron 4 mg + dexamethasone 8 mg; TIVA reduces PONV vs. volatiles

TOPIC 8 - BURNS

Station 1 - Initial Assessment

ABCDE approach + airway priority:

Inhalation injury signs (highest priority):

Singed nasal hairs/eyebrows
Carbonaceous sputum
Hoarse voice, stridor
Facial burns, oropharyngeal soot
Mechanism: enclosed space fire
If signs present: immediate intubation (airway edema progresses rapidly)

%TBSA Estimation:

Rule of Nines (adults):
- Head: 9%, Each arm: 9%, Anterior trunk: 18%, Posterior trunk: 18%, Each leg: 18%, Perineum: 1%
Palmar method: patient's palm = 1% TBSA (for irregular/scattered burns)
Lund-Browder chart: most accurate, accounts for pediatric proportions

Burn depth assessment:

Depth	Appearance	Pain	Healing
Superficial (1°)	Red, dry, no blisters	Painful	<7 days, no scar
Superficial partial (2°)	Blisters, moist, pink	Very painful	7-14 days
Deep partial (2°)	White/red mottled, blisters	Reduced pain	>21 days, scar likely
Full thickness (3°)	Leathery, white/brown, charred	Painless	No self-healing, needs graft
4°	Down to bone/muscle	Painless	Amputation often required

Station 2 - Clinical Assessment and Diagnostic Reasoning

Parkland formula (fluid resuscitation):

4 mL x body weight (kg) x %TBSA burned = total Ringer's Lactate in first 24h
Give 1/2 in first 8h from time of burn (not from time of arrival)
Give 1/2 in next 16h
Children: add maintenance dextrose-containing fluid
Monitor with UO: 0.5-1 mL/kg/hr in adults; 1 mL/kg/hr in children
Modified Brooke formula: 2 mL/kg/% TBSA (alternative)

When to start fluid resuscitation: Burns >15-20% TBSA in adults; >10-15% in children

Burn depth assessment tools: Clinical exam, laser Doppler imaging, indocyanine green angiography

Labs/monitoring: ABG (carboxyhemoglobin in CO poisoning), lactate, FBC, U&E, glucose, coagulation, carbon monoxide level, cyanide toxicity (industrial fires)

Station 3 - Recognition of Critical Findings

Life-threatening burn complications:

Complication	Features	Action
CO poisoning	Cherry red skin, headache, confusion, COHb >10%	100% O2 (reduces CO half-life from 4-5h to 60-90 min); hyperbaric O2 if severe
Cyanide poisoning	Industrial fires, rapid collapse, high lactate	Hydroxocobalamin 5g IV
Inhalation injury	Stridor, respiratory distress	Early intubation
Circumferential burns (escharotomy)	Limb: pulseless, painful, paralyzed, pale, paresthetic; Chest: rising airway pressures	Escharotomy (full-thickness incision through eschar); fasciotomy if muscle involvement
Burn shock	Hypovolemia >6-8h after major burn	Aggressive Parkland resuscitation
Sepsis	Common after 48-72h; silver sulfadiazine, infection surveillance	Cultures, targeted antibiotics

Referral criteria (specialized burn unit):

10% TBSA in children; >15% TBSA in adults
Full thickness burns >5% TBSA
Burns to face, hands, feet, genitalia, perineum, major joints
Circumferential burns
Inhalation injury
Electrical/chemical burns
Associated trauma
Extremes of age

Station 4 - Management Plan

Burn wound care:

Superficial: cool with room-temperature water (15-20 min within 3h of burn, not ice)
Dressings: moist, non-adherent (Mepitel, silver-impregnated - Acticoat, Mepilex Ag)
Silver sulfadiazine (SSD): broad-spectrum antimicrobial; avoid on face and in pregnancy
Topical mafenide acetate: penetrates eschar, good for deep burns

Surgical management:

Early excision and grafting (within 48-72h): reduces infection, improves survival for full-thickness burns
Split-thickness skin graft (STSG): 0.012-0.018 inch; donor site heals by secondary intention
Meshing: expands graft 1.5-6x to cover larger areas
Biological substitutes: cadaveric allograft (temporary), Integra (dermal substitute)

Nutrition in burns:

Hypermetabolic state (Curreri formula: 25 kcal/kg + 40 kcal/% TBSA burn)
Early enteral nutrition within 6h
Protein: 2-3 g/kg/day
Micronutrients: vitamins C, E, zinc, selenium

Pain management: Multimodal (IV morphine/ketamine + paracetamol + midazolam for dressing changes)

TOPIC 9 - BASIC SURGICAL SKILLS AND ANASTOMOSIS

Station 1 - Initial Assessment

Pre-operative assessment for anastomosis:

Patient factors: malnutrition (albumin <30 = high leak risk), steroids, immunosuppression, diabetes, BMI
Local factors: tissue quality, blood supply, tension, contamination, bowel preparation
Technical factors: surgeon experience, correct instrument/suture choice

Anastomotic principles (the 5 requirements):

Adequate blood supply to both ends
Tension-free anastomosis
No distal obstruction
Healthy tissue (not inflamed, irradiated, or ischemic)
Watertight seal (no leakage)

Station 2 - Clinical Assessment and Diagnostic Reasoning

Suture materials:

Property	Absorbable	Non-absorbable
Examples	Vicryl (PG 910), PDS, Monocryl	Prolene, Nylon, Mersilk
Degradation	Enzymatic/hydrolytic	None
Tissue reaction	More reaction (braided > monofilament)	Less reaction
Use	GI anastomosis, fascial closure, subcuticular	Vascular, skin, hernia mesh fixation

Suture configuration:

Interrupted: more secure, each suture independent, less ischemia - anastomosis, skin
Continuous (running): faster, watertight, everts edges - vascular, GI inner layer
Everting: used in vascular anastomosis (intima-to-intima apposition)
Inverting: used in GI anastomosis (Lembert, Connell) - serosa-to-serosa

Bowel anastomosis options:

Hand-sewn: single-layer interrupted (PDS/Vicryl) vs. two-layer
Stapled (GIA/ILS/EEA): equivalent leak rates; faster
End-to-end, end-to-side, side-to-side configurations

Anastomotic leak rate: Colorectal 3-10%; esophageal 10-20%; small bowel <1-3%

Station 3 - Recognition of Critical Findings

Anastomotic leak (most feared complication):

Onset: day 3-7 postoperatively
Signs: fever, tachycardia, abdominal pain, ileus, purulent/fecal drain output, peritonitis
Radiological: CT with oral contrast showing extraluminal air/fluid/contrast
Clavien-Dindo grade IIIb or higher if requiring surgical re-intervention

Bowel ischemia post-anastomosis:

Signs: blue/black bowel at time of surgery, dark drain output, severe ileus, rising lactate
Action: return to OR, resection of ischemic segment, consider stoma

Stapler misfires:

Always test anastomosis (air leak test: air insufflation with anastomosis submerged in saline)
Donut examination: confirm complete circles in circular stapler anastomosis

Station 4 - Management Plan

Anastomotic leak management:

Well-contained + hemodynamically stable: CT-guided drainage, IV antibiotics, NPO, parenteral nutrition
Peritonitis/hemodynamic instability: return to OR - washout + resection + stoma (Hartmann's procedure)
Proximal defunctioning stoma: reduces fecal loading of anastomosis (loop ileostomy/colostomy)

Stoma creation principles:

Site marked preoperatively by stoma nurse (away from bony prominences, skin folds, belt line)
End colostomy: left iliac fossa, flush/slightly everted
Loop ileostomy: right iliac fossa, spout 2-3 cm (due to corrosive content)
Complications: retraction, prolapse, parastomal hernia, stenosis, ischemia

Principles of wound closure - abdominal fascia:

Mass closure: #1 PDS continuous with small bites technique (5mm from edge, 5mm apart)
Suture length to wound length ratio ≥4:1 (reduces dehiscence)
Avoid excessive tension (strangulates tissue, increases SSI)

TOPIC 10 - ARTERIAL DISORDERS

Station 1 - Initial Assessment

The 6 P's of acute limb ischemia (ALI):

Pain - sudden, severe, unrelenting
Pallor - white/mottled extremity
Pulselessness - absent distal pulses
Paresthesia - numbness, tingling (indicates ischemic neuropathy)
Paralysis - inability to move foot/hand (indicates irreversible ischemia)
Perishing cold (Poikilothermia)

Clinical assessment:

Bilateral limb comparison: pulses, ABIs, skin color/temperature
Differentiate embolism vs. thrombosis:

Feature	Embolism	Thrombosis
Onset	Sudden (minutes)	Gradual (hours-days)
Prior claudication	No	Yes
AF or cardiac source	Yes	No
Contralateral limb	Normal	May have disease
Severity	More severe (no collaterals)	Less severe (collaterals)

Station 2 - Clinical Assessment and Diagnostic Reasoning

Peripheral artery disease (PAD) - chronic:

Fontaine Classification:

Stage I: Asymptomatic
Stage IIa: Claudication >200m
Stage IIb: Claudication <200m
Stage III: Rest pain
Stage IV: Ulceration/gangrene (critical limb ischemia)

Rutherford Classification (I-VI): Used in contemporary vascular surgery

Ankle-Brachial Index (ABI):

Normal: 1.0-1.3
Mild PAD: 0.7-0.9
Moderate: 0.5-0.7
Severe: <0.5
Critical limb ischemia: <0.4
Incompressible (calcified): >1.3 (DM, elderly)

Imaging:

Duplex USS: first-line
CT angiography (CTA): preoperative planning
Digital subtraction angiography (DSA): gold standard + endovascular treatment same sitting

Aortic aneurysm (AAA):

Defined as aortic diameter >3 cm or >1.5x normal
Symptomatic: pain (back/abdominal), pulsatile mass
Rupture: hypotension + back pain + pulsatile mass = surgical emergency
Screening: USS in men aged 65+

Station 3 - Recognition of Critical Findings

Vascular emergencies:

Condition	Critical Finding	Action
Acute limb ischemia (ALI)	Paralysis + paresthesia = irreversible if not reperfused within 4-6h	IV heparin 5000 units immediately; emergency revascularization
Ruptured AAA	Hypotension + pulsatile mass + back pain	2 large IVs, type & cross, permissive hypotension (SBP 50-70 mmHg until OR), emergency EVAR/open repair
Aortic dissection (Type A)	Tearing chest/back pain, unequal BP in arms, wide mediastinum	Immediate surgical repair (Type A); BP control + surveillance (Type B)
Compartment syndrome	ACS: pain out of proportion, pain on passive stretch, tense compartment	Immediate fasciotomy if pressure >30 mmHg or within 30 mmHg of diastolic BP
Mesenteric ischemia	Severe pain out of proportion to exam, elevated lactate, AF/low flow state	Emergency CT angiography; revascularization or bowel resection

ALI - Rutherford Classification urgency:

Class I: viable - no immediate threat
Class IIa: marginally threatened - urgent
Class IIb: immediately threatened - emergency
Class III: irreversible - major amputation

Station 4 - Management Plan

Acute limb ischemia management:

IV heparin immediately (5000 U bolus, then 1000 U/h infusion) - prevents propagation
Embolism with cardiac source + viable limb: embolectomy (Fogarty catheter)
Thrombosis on background PAD: thrombolysis (alteplase/urokinase via catheter) vs. bypass
On-table angiogram post-embolectomy to confirm patency
Post-reperfusion: fasciotomy if prolonged ischemia (>6h) - reperfusion injury + compartment syndrome
Monitor for myonecrosis: hyperkalemia, myoglobinuria (IV fluids, bicarbonate, renal replacement if needed)

PAD chronic management:

Medical: antiplatelet (aspirin/clopidogrel), statin, ACE inhibitor, BP control, smoking cessation, exercise rehabilitation
Endovascular: PTA (percutaneous transluminal angioplasty) ± stenting for focal disease (TASC A/B)
Surgical bypass: for diffuse disease (TASC C/D); autologous vein graft (long saphenous) preferred; PTFE for above-knee bypass

AAA management:

Surveillance: USS monitoring if 3-5.4 cm (every 1-3 years depending on size)
Intervention threshold: >5.5 cm men, >5.0 cm women, or >1 cm growth/year, or symptomatic
EVAR (endovascular): lower perioperative mortality (1-2%); requires suitable anatomy
Open repair: more durable (30-year patency); higher perioperative risk (3-5%)

Carotid disease:

Symptomatic stenosis >50%: carotid endarterectomy (CEA) within 2 weeks of TIA/stroke
Asymptomatic stenosis >70%: CEA if surgical risk low
Antiplatelet + statin regardless of revascularization decision

Quick-Reference OSCE Framework

For any station in General Surgery, apply this mental framework:

Station 1 checklist:

ABCDE systematic approach
Identify mechanism / chief complaint
Immediate life threats
Two large-bore IVs + bloods + monitoring
Patient communication

Station 2 checklist:

Integrate history + exam + labs + imaging
Apply validated scoring tools (ATLS classes, Fontaine, LRINEC, ASA, etc.)
Formulate differential then working diagnosis
Grade severity

Station 3 checklist:

Scan for red flags and immediate threats to life/limb
Apply the "cannot miss" diagnoses
Time-critical decisions (surgical threshold, reversal agents, antidotes)
Escalation pathway

Station 4 checklist:

Evidence-based initial management (resuscitate → investigate → source control → definitive)
Indicate: admission level (ward/HDU/ICU), specialty consult, transfer
Outline definitive treatment
Complications and follow-up plan

Sources: Sabiston Textbook of Surgery; Schwartz's Principles of Surgery (11e); Fischer's Mastery of Surgery (8e); Tintinalli's Emergency Medicine; Goldman-Cecil Medicine; Miller's Anesthesia (10e); Current Surgical Therapy (14e); ATLS 10th Edition principles; Surviving Sepsis Campaign guidelines.

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