A 32-year-old man presents to the surgical outpatient clinic 10 days after undergoing an open appendicectomy. On examination, his surgical wound shows erythema, warmth, and purulent discharge. The wound edges are separated, and there is visible granulation tissue at the base. His haemoglobin is 9.2 g/dL, serum albumin 2.8 g/dL, and random blood glucose 280 mg/dL. He has a 5-year history of poorly controlled type 2 diabetes mellitus. Which of the following is the PRIMARY factor delaying his wound healing in the inflammatory phase?

Explanation

## Wound Infection and Delayed Healing in Diabetes ### Clinical Context This patient presents with a wound infection (purulent discharge, erythema, warmth) 10 days post-operatively, during the **inflammatory phase** (typically days 0–5, but can extend with complications). His poorly controlled diabetes (random glucose 280 mg/dL) is the key predisposing factor. ### Pathophysiology of Hyperglycaemia on Wound Healing **Key Point:** Hyperglycaemia impairs the inflammatory phase by: 1. **Neutrophil dysfunction** — reduced chemotaxis, phagocytosis, and oxidative burst 2. **Impaired opsonisation** — glycation of immunoglobulins reduces bacterial coating 3. **Reduced complement activation** — defective C3 and C5 function 4. **Increased bacterial adherence** — high glucose favours pathogen colonisation ### Why This Delays Healing | Phase | Normal Timeline | With Infection/Diabetes | Key Process | |-------|---|---|---| | **Inflammatory** | Days 0–5 | Days 0–14+ | Neutrophil infiltration, bacterial clearance, cytokine release | | **Proliferative** | Days 5–21 | Delayed onset | Fibroblast migration, collagen synthesis, angiogenesis | | **Remodelling** | Days 21–365+ | Prolonged | Collagen cross-linking, scar maturation | **Clinical Pearl:** The wound infection visible at day 10 (purulent discharge, separated edges) indicates **failure of the inflammatory phase** — the neutrophils have not effectively cleared bacteria, allowing secondary infection to establish. ### Additional Factors in This Patient - **Anaemia (Hb 9.2 g/dL)** — reduces oxygen delivery to the wound, impairing oxidative killing and collagen synthesis - **Hypoalbuminaemia (2.8 g/dL)** — impairs fibroblast function and collagen deposition in the proliferative phase - **Hyperglycaemia** — the PRIMARY driver of neutrophil dysfunction in the inflammatory phase **High-Yield:** Diabetic patients have a **3–5-fold increased risk** of surgical site infections (SSI) due to impaired neutrophil function, not just poor glycaemic control at the time of surgery. ### Management Implications 1. **Tight glycaemic control** (target 140–180 mg/dL perioperatively) 2. **Aggressive wound care** — debridement of necrotic tissue, drainage of pus 3. **Nutritional support** — albumin, vitamin C, zinc supplementation 4. **Antibiotic therapy** — broad-spectrum cover until culture results available