Skin Wounds: Assessment and Management

Introduction to MCCQE1 Preparation

Understanding the pathophysiology, assessment, and management of skin wounds is a fundamental competency for the MCCQE1. As a future Canadian physician, you are expected to demonstrate the Medical Expert role from the CanMEDS framework by applying evidence-based strategies to acute and chronic wound care.

This guide focuses on the high-yield topics required for the Medical Council of Canada Qualifying Examination Part I, emphasizing Canadian clinical practice guidelines.

🇨🇦 Canadian Context

In Canada, chronic wounds affect a significant portion of the aging population and those with diabetes. Familiarity with resources from Wounds Canada and the Public Health Agency of Canada (PHAC) regarding tetanus prophylaxis is essential for the exam.

Classification of Wounds

Wounds are generally classified based on the timeline of healing and the mechanism of injury. Understanding this classification is the first step in determining the appropriate management plan.

Acute Wounds

Acute Wounds typically heal through an orderly and timely reparative process.

Examples: Surgical incisions, traumatic lacerations, abrasions, burns.
MCCQE1 Focus: Suturing techniques, tetanus prophylaxis, and infection prevention.

Phases of Wound Healing

For the MCCQE1, you must understand the physiological process to identify when healing is delayed.

Hemostasis (Immediate): Vasoconstriction, platelet aggregation, fibrin clot formation.
Inflammation (Days 0-3): Neutrophil and macrophage infiltration to clear debris and bacteria.
Proliferation (Days 3-21): Granulation tissue formation, angiogenesis, epithelialization, wound contraction.
Maturation/Remodeling (Day 21 - 1+ years): Collagen reorganization (Type III to Type I). Tensile strength increases (max 80% of original skin).

Clinical Assessment

History Taking

When a patient presents with a wound, specific data points are required to rule out complications and guide treatment.

Mechanism: How did it happen? (Clean vs. Dirty)
Time of injury: Crucial for the “Golden Period” (generally <12-24 hours for face, <6-12 hours for extremities).
Foreign body: Sensation of something inside?
Functional status: Numbness, loss of function (nerve/tendon damage).
Tetanus status: Date of last booster.
Comorbidities: Diabetes, immunosuppression, peripheral vascular disease.

Physical Examination

Use the TIME principle for wound bed assessment (common in Canadian nursing and medical care):

T - Tissue (Viable vs. Non-viable/Slough/Eschar) I - Infection/Inflammation M - Moisture (Exudate level) E - Edge (Advancing vs. Undermined)

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Red Flag: Always assess neurovascular status (distal pulses, sensation, capillary refill, 2-point discrimination) before administering local anesthesia, as the anesthetic can mask nerve deficits.

Management of Acute Wounds

Follow these steps for standard laceration management in an emergency or family practice setting.

Step 1: Hemostasis

Apply direct pressure. Avoid blind clamping in deep wounds to prevent nerve injury.

Step 2: Anesthesia

Local Infiltration: Lidocaine 1% or 2% (max dose 4.5 mg/kg without epinephrine, 7 mg/kg with epinephrine).
Epinephrine Use: Safe for most areas. Historically avoided in digits/nose/penis, but current Canadian evidence suggests it is safe in digits if no peripheral vascular disease exists (WALANT technique).
Topical: LET (Lidocaine, Epinephrine, Tetracaine) for pediatric facial lacerations.

Step 3: Irrigation and Cleaning

This is the most important factor in decreasing infection.

Volume: Copious amounts (e.g., 50-100 mL per cm of wound).
Solution: Potable tap water is as effective as sterile saline for cleaning most acute wounds (Cochrane Review).
Pressure: High-pressure irrigation (e.g., 18G angiocatheter on a 30-60cc syringe).

Step 4: Exploration and Debridement

Remove foreign bodies.
Excise devitalized tissue (creates a sharp wound edge for better healing).
Check for tendon or joint capsule involvement.

Step 5: Closure

Select the appropriate method based on wound type and timing.

Primary Intention: Sutures, staples, tissue adhesives (Dermabond). Immediate closure.
Secondary Intention: Wound left open to heal by granulation. Used for infected wounds, dog bites (extremities), or significant tissue loss.
Tertiary Intention (Delayed Primary): Wound left open for 3-5 days to allow drainage/cleaning, then closed. Used for highly contaminated wounds.

Tetanus Prophylaxis (Canadian Immunization Guide)

This is a frequent topic on the MCCQE1. You must know when to give the Tdap/Td vaccine and Tetanus Immune Globulin (TIG).

History of Tetanus Vaccine	Clean, Minor Wounds	All Other Wounds (Dirty)*
Unknown or <3 doses	Give Tdap/Td**	Give Tdap/Td PLUS** TIG
3 or more doses	Give Tdap/Td if last dose >10 years ago	Give Tdap/Td if last dose >5 years ago

Dirty wounds: Contaminated with dirt, feces, soil, saliva; puncture wounds; avulsions; missiles; crushing; burns; frostbite.
Tdap: Tetanus, Diphtheria, Acellular Pertussis (Adacel/Boostrix). Preferred for adults who have not had a pertussis booster in adulthood.

Suture Removal Timing

Memorize these timelines for the exam. Leaving sutures in too long causes “railroad track” scarring; too short risks dehiscence.

Face: 3-5 days
Scalp: 7-10 days
Trunk: 10-14 days
Upper Extremities: 10-14 days
Lower Extremities: 14-21 days (highest tension)
Over Joints: 14-21 days

Chronic Wounds: Pressure Injuries

Pressure injuries (ulcers) are high-yield for Geriatrics and Internal Medicine questions.

Staging System (NPUAP/EPUAP)

Stage 1

Non-blanchable erythema of intact skin.

Stage 2

Partial-thickness skin loss with exposed dermis. Wound bed is pink/red, moist. No slough.

Stage 3

Full-thickness skin loss. Adipose is visible. Granulation tissue and epibole (rolled edges) often present.

Stage 4

Full-thickness skin and tissue loss with exposed fascia, muscle, tendon, ligament, cartilage, or bone.

Unstageable: Obscured by slough or eschar. Deep Tissue Injury: Persistent non-blanchable deep red, maroon, or purple discoloration.

Key Points to Remember for MCCQE1

Bites:
- Cat bites: High risk of infection (Pasteurella multocida). Prophylactic antibiotics (Amoxicillin-Clavulanate) are almost always indicated. Do not close primarily (unless on face and cosmetically vital).
- Human bites: “Fight bite” (knuckle vs. tooth). High risk of Eikenella corrodens. Treat aggressively; check for extensor tendon damage.
Antibiotics: Not routine for simple, clean lacerations. Indicated for:
- Deep puncture wounds.
- Wounds on hands/feet.
- Crush injuries.
- Immunocompromised patients.
- Bite wounds.
Keloids vs. Hypertrophic Scars:
- Hypertrophic: Stays within wound boundaries, regresses over time.
- Keloid: Extends beyond boundaries, does not regress, genetic predisposition (darker skin types).

Sample Question

Scenario

A 42-year-old male farmer presents to the rural emergency department with a puncture wound to his left foot. He stepped on a rusty nail in his barn 4 hours ago. He removed the nail immediately. The wound appears deep but not actively bleeding. There is no neurovascular deficit. He is unsure of his vaccination history but thinks he had “some shots” as a child, though he has not seen a doctor in over 20 years.

Question

Which of the following is the most appropriate management regarding tetanus prophylaxis for this patient?

A. Administer Tdap vaccine only.
B. Administer Tetanus Immune Globulin (TIG) only.
C. Administer Tdap vaccine and Tetanus Immune Globulin (TIG).
D. Prescribe oral antibiotics and observe; no prophylaxis needed due to childhood history.
E. Order serum tetanus antibody levels before administering prophylaxis.

Explanation

The correct answer is:

C. Administer Tdap vaccine and Tetanus Immune Globulin (TIG).

Detailed Explanation: This question tests the application of the Canadian Immunization Guide recommendations for tetanus prophylaxis.

Assess the Wound: A puncture wound from a rusty nail in a barn is considered a dirty/contaminated wound (prone to Clostridium tetani).
Assess the History: The patient’s history is unknown/uncertain (“unsure”, “thinks he had some shots”, “not seen doctor in 20 years”). In the context of tetanus guidelines, an uncertain history is treated as unimmunized (or fewer than 3 doses).
Apply the Rule:
- For a dirty wound + unknown/<3 doses history: The patient requires passive immunization (TIG) for immediate protection AND active immunization (Tdap/Td) to start the series for long-term immunity.

Option A: Incorrect. Vaccine alone is insufficient for immediate protection in a dirty wound with uncertain history; the antibody response takes time.
Option B: Incorrect. TIG provides immediate protection but no long-term immunity. He needs the vaccine series started.
Option D: Incorrect. Antibiotics do not replace prophylaxis against tetanus toxin.
Option E: Incorrect. In an acute trauma setting with a dirty wound, prophylaxis should not be delayed for antibody testing.

Canadian Guidelines & Resources

For further study, consult these authoritative Canadian sources:

Public Health Agency of Canada (PHAC): Canadian Immunization Guide: Part 4 - Active Vaccines: Tetanus Toxoid.
Wounds Canada: Best Practice Recommendations for the Prevention and Management of Wounds.
Choosing Wisely Canada: Recommendations on antibiotic stewardship in wound care.

References

Public Health Agency of Canada. (2018). Canadian Immunization Guide. Tetanus Toxoid. Available at: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-22-tetanus-toxoid.html
Wounds Canada. (2021). Foundations of Best Practice for Skin and Wound Management.
Medical Council of Canada. (2023). MCCQE Part I Objectives: Skin and Subcutaneous Tissue.
Tintinalli, J. E., et al. (2020). Tintinalli’s Emergency Medicine: A Comprehensive Study Guide (9th ed.). McGraw-Hill Education.
Fernandez, R., & Griffiths, R. (2012). Water for wound cleansing. Cochrane Database of Systematic Reviews.