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SU5.1-4,SU6.1-2 | Wound Healing and Surgical Infection — PBL Case
CLINICAL SETTING
A 45-year-old labourer presents to the surgical outpatient clinic three weeks after sustaining a wound to his left lower leg at a construction site. He was treated at a local clinic where the wound was sutured closed on the day of injury. He now complains that the wound has reopened, is discharging foul-smelling fluid, and is painful. He has untreated type 2 diabetes. This case develops in three triggers; discuss each fully before revealing the next.
Trigger 1: The wound that broke down
On examination there is a partially dehisced wound with surrounding erythema and purulent discharge. The patient explains the original wound had been dirty, with soil contamination, but was stitched closed immediately. His random blood glucose today is 19 mmol/L.
DISCUSSION POINTS
- Why is it unsafe to close a contaminated wound by primary intention, and what mode of healing would have been more appropriate at the time of injury?
- Which local and systemic factors in this patient have impaired healing and predisposed to wound breakdown, and through which phases of healing do they act?
- How would you assess and classify this wound now, both morphologically and by contamination class?
Click to reveal Trigger 2: The infection declares itself (discuss previous trigger first!)
Trigger 2: The infection declares itself
Over the next 24 hours the leg becomes increasingly swollen and the patient develops fever and tachycardia. He reports that the pain is now severe and seems far worse than the appearance of the leg would suggest. There is a patch of dusky skin and you feel crepitus on palpation.
DISCUSSION POINTS
- What complication must now be excluded urgently, and which clinical features point to it?
- What are the two pillars of managing established surgical infection, and in which order must they be applied here?
- How does the pathogen–host–environment balance explain why this particular patient developed a severe infection?
Click to reveal Trigger 3: Source control and prevention (discuss previous trigger first!)
Trigger 3: Source control and prevention
The patient is taken urgently to theatre for radical debridement of necrotic tissue, started on broad-spectrum antibiotics, and his diabetes is brought under control. He recovers but is left with a large open wound that will heal by secondary intention. He asks why the original clinic's treatment failed.
DISCUSSION POINTS
- How would you explain to the patient, in plain terms, why immediate suturing of his contaminated wound contributed to this outcome?
- How will this large open wound now heal, and what does management by secondary intention involve?
- What measures at the first presentation (wound class assessment, debridement, delayed closure, tetanus prophylaxis, antibiotic decisions, glycaemic control) could have prevented this complication?
Group Task Assignments
- Create a decision aid that maps wound contamination class to the appropriate mode of closure (primary, delayed primary/tertiary, secondary intention).
- Prepare a concise summary of the early warning features of necrotizing soft-tissue infection and the immediate management steps.
- Draft an objective medico-legal-style wound description for the original injury, modelling accurate documentation of site, size, shape, edges and depth.
Learning Issues
Research these questions and bring your findings to the discussion.
- [SU5.1] What are the phases of normal wound healing and the local and systemic factors that impair it?
- [SU5.3] How are wounds classified morphologically and by contamination class, and how does classification guide the choice of closure and management?
- [SU6.1] What is the aetiology and pathogenesis of surgical infection, including the recognition of necrotizing soft-tissue infection?
- [SU6.2] What are the principles of source control and the appropriate use of prophylactic versus therapeutic antibiotics in surgical infection?