Wound Healing

Core Concepts

The four phases of healing

(Educational overview — phases overlap; timescales vary by wound, person, and source.)

1. Hemostasis (immediate) — blood vessels constrict and a clot forms (platelets + fibrin) to stop bleeding. The clot also releases signaling chemicals (growth factors) that summon the next phase — the "scab" beginning.
2. Inflammatory phase (roughly days 1–4+, overlapping) — vessels dilate, bringing redness, warmth, and swelling (the cardinal signs of inflammation), and immune cells (neutrophils, then macrophages) flood the site to kill bacteria and clear debris while releasing signals that set up repair. A wound is not "infected" just because it looks slightly red and warm in the first days — some inflammation is normal healing.
3. Proliferative phase (roughly days 4–21, overlapping) — construction: new blood vessels form (angiogenesis) to feed the area, fibroblasts lay down collagen, granulation tissue (red, moist, bumpy new tissue) fills the wound from the bottom up, and epithelial cells migrate across the surface (epithelialization). The wound contracts as new tissue pulls edges together.
4. Maturation / remodeling phase (weeks to months) — collagen is reorganized along lines of tension, the wound strengthens, and excess tissue is removed. The final scar never quite matches original skin — it gains strength over months but typically plateaus below 100% of original tensile strength.

Types of healing by intention

Introduced in Wound Classification; here's the biology:

• Primary intention — clean, well-approximated edges (sutured incisions). Minimal tissue loss; minimal granulation; thin scar; fastest, strongest result.
• Secondary intention — wound left open (tissue loss, contamination, infection — many pressure injuries, abscesses). Fills with granulation from the bottom up, then epithelializes. Slower, more scarring, higher infection risk — but necessary when closure isn't safe.
• Tertiary intention — left open initially (to drain or control infection), then surgically closed days later.

Factors that promote healing

The nurse's checklist for giving healing its best chance:

• Nutrition — healing is expensive: protein (new tissue), calories (energy), vitamin C (collagen formation), zinc (cell division), fluids (tissue hydration). Malnourished patients heal poorly; consult the dietitian — never invent supplements or doses.
• Oxygenation and perfusion — healing tissue needs oxygen and nutrients delivered by blood. Impaired circulation (vascular disease, diabetes, heart failure, hypotension) or oxygenation (lung disease, anemia) slows healing. Smoking is a major modifiable risk — nicotine constricts vessels; carbon monoxide displaces oxygen.
• Moisture balance — a moist wound environment supports cell migration and granulation; drying kills new cells, while excess moisture macerates tissue. Modern dressings are designed around this balance; the right dressing is provider-ordered and product/policy specific.
• Cleanliness and infection control — bacteria consume resources, produce toxins, and keep the wound stuck in the inflammatory phase. Aseptic technique, hand hygiene, and daily assessment are core nursing jobs.
• Offloading / pressure relief — for pressure injuries, healing cannot occur while pressure keeps crushing the tissue (see Skin Integrity).
• Blood sugar control — elevated glucose impairs immune function and healing; for patients with diabetes, glucose management (as ordered) is part of wound care.
• Age and general health — younger, healthier patients heal faster; older adults and patients with chronic conditions heal more slowly (see Structures and Function of the Skin).

Complications the nurse watches for

• Infection — spreading redness, warmth, increasing pain, purulent drainage, odor, fever, or a wound that was improving and starts regressing. Report promptly; wound culture is provider-ordered.
• Dehiscence — wound edges separate (usually days after surgery); risks include poor nutrition, coughing/straining, infection, poor closure. Sudden increased drainage or a sensation of "something giving way" can herald it.
• Evisceration — dehiscence with abdominal organs protruding. Emergency: cover with sterile saline-soaked dressings per policy, keep the patient supine with knees bent, notify the provider/surgeon immediately — do NOT push organs back in.
• Hemorrhage — bleeding, especially in the first 24–48 hours after surgery; can be external (drainage saturating dressings) or internal (swelling, bruising, falling blood pressure, rapid pulse).
• Fistula — an abnormal connection between internal structures or between an organ and the skin surface (can develop after surgery, inflammation, or radiation).
• Hypertrophic scar and keloid — excessive scar tissue; keloids extend beyond the original wound and are more common in darker skin and certain genetic backgrounds — a normal variation, not a disease, but it can affect appearance and movement.
• Contracture — scar tissue that shrinks and tightens, potentially restricting joint movement (distinct from neuromuscular contracture in Chapter 23 — see Common Confusions).

The nurse's role: assess, support, document

Daily (or per orders): assess the wound (size, depth, tissue type, drainage, edges, surrounding skin, pain) and the systemic signs of infection (temperature, chills, lab results per provider interpretation); perform ordered dressing care with aseptic technique; ensure nutrition, hydration, repositioning, and offloading; manage drains per policy; document consistently so healing trends are visible. Teach the patient and family what healing looks like at each stage, what to report (increasing redness, drainage, fever, wound separation), and why nutrition and position matter. Scope note: what may be delegated to UAP and which assessments require a registered nurse are governed by state practice acts and facility policy.

Common Confusions