General Surgery
Wound Healing and Management
MBBS surgery notes on wound healing: phases of repair, primary and secondary intention, keloids and wound classification, mapped to NMC codes SU5.1 to SU6.2.
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Wound Healing and Management
MBBS surgery notes on wound healing: phases of repair, primary and secondary intention, keloids and wound classification, mapped to NMC codes SU5.1 to SU6.2.
This chapter explains the biology of wound healing and its clinical management. It covers the phases of repair, the modes of healing, the factors that delay it, abnormal scarring and the classification of surgical wounds by contamination.
High-yield: Wound Healing and Management
- Wound healing proceeds through overlapping phases of haemostasis, inflammation, proliferation and remodelling.
- The inflammatory phase lasts a few days, the proliferative phase brings granulation and epithelialisation over weeks, and remodelling continues for months to a year.
- Healing by primary intention occurs when clean wound edges are apposed, giving a fine scar with minimal tissue loss.
- Healing by secondary intention occurs when a wound is left open to granulate and contract, used for contaminated or tissue-deficient wounds.
- Delayed primary closure means closing a contaminated wound after a few days once infection risk has fallen.
- Collagen is central to wound strength; type III collagen laid down early is gradually replaced by stronger type I during remodelling.
- Wound tensile strength reaches only about 20% of normal at three weeks and never regains full pre-injury strength.
- Local factors delaying healing include infection, ischaemia, foreign bodies, tension and prior irradiation.
- Systemic factors delaying healing include diabetes, malnutrition, vitamin C and zinc deficiency, steroids and smoking.
- A hypertrophic scar stays within the wound margins and may regress, whereas a keloid extends beyond the original wound and rarely regresses.
- Keloids are commonest in darker skin and over the sternum, earlobes and shoulders, and tend to recur after simple excision.
- Surgical wounds are classified as clean, clean-contaminated, contaminated and dirty, which predicts infection risk and antibiotic need.
- Wound dehiscence often heralds a burst abdomen and may be preceded by a pink serosanguinous discharge from the wound.
- Negative pressure wound therapy promotes granulation and removes exudate in large or complex open wounds.
- Adequate debridement of dead tissue is the single most important step in managing a contaminated or chronic wound.
Phases of wound healing
- **Haemostasis:** Immediate: vasoconstriction, platelet plug and clot formation seal the wound.
- **Inflammation:** Days 1 to 5: neutrophils then macrophages clear debris and bacteria and release growth factors.
- **Proliferation:** Days to weeks: fibroblasts lay collagen, angiogenesis, granulation tissue and epithelialisation.
- **Remodelling:** Weeks to a year: type III collagen replaced by type I, scar strengthens but stays weaker than normal skin.
NMC competencies in this chapter
- **SU5.1:** Phases and physiology of wound healing
- **SU5.2:** Types of wound healing and factors affecting it
- **SU5.3:** Classification and management of surgical wounds
- **SU5.4:** Abnormal scarring and chronic wounds
- **SU6.2:** Principles of wound care and dressings
Frequently Asked Questions
What are the phases of wound healing?
Haemostasis, inflammation, proliferation and remodelling. They overlap, with granulation and epithelialisation in the proliferative phase and collagen maturation continuing during remodelling for up to a year.
How does healing by primary and secondary intention differ?
Primary intention apposes clean wound edges for a fine scar, while secondary intention leaves a wound open to granulate and contract, used when there is tissue loss or contamination.
What is the difference between a keloid and a hypertrophic scar?
A hypertrophic scar stays within the wound margins and may regress, whereas a keloid grows beyond the original wound, is commoner in darker skin and tends to recur after excision.
Which factors delay wound healing?
Local factors such as infection, ischaemia, tension and foreign bodies, and systemic factors such as diabetes, malnutrition, steroids, smoking and vitamin C or zinc deficiency.
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