What is the primary outcome of delayed primary wound closure?

Delayed Primary Wound Closure: Effects on Wound Healing and Outcomes

Delayed primary wound closure results in increased angiogenesis (a), which is the correct answer. This technique promotes the development of granulation tissue with enhanced blood supply and oxygenation to the wound bed, which is critical for optimal wound healing 1.

Mechanism of Delayed Primary Closure

Delayed primary closure (DPC) is a surgical technique where contaminated or dirty wounds are initially left open with dressings for several days (typically 3-5 days) before being closed. This approach has several effects on wound healing:

1. Increased Angiogenesis:

   • DPC stimulates the formation of granulation tissue with enhanced blood supply
   • The open wound management phase allows for increased wound oxygenation and blood supply development 1
   • This increased vascularity supports better healing once the wound is closed

2. Wound Strength:

   • Contrary to option (b), DPC does not result in decreased wound strength
   • The development of healthy granulation tissue actually provides a better foundation for wound closure
   • The increased vascularity supports better collagen formation and wound healing

3. Collagen Content:

   • Option (c) is incorrect as DPC does not result in lower collagen content
   • The granulation tissue formed during the open phase has robust collagen formation
   • Better blood supply supports optimal collagen synthesis

4. Scar Width:

   • Option (d) is incorrect as DPC does not necessarily result in a wider scar
   • When properly executed, DPC can actually result in better cosmetic outcomes by reducing tension on wound edges

Evidence Supporting DPC in Contaminated Wounds

DPC has been extensively studied in contaminated surgical wounds:

• A prospective study found that only 3% of contaminated wounds managed with DPC developed infection compared to 27% of those with primary closure 2

• In a 2023 study comparing primary closure versus DPC following emergency laparotomy, the overall incidence of surgical site infection was significantly lower in the DPC group (p=0.0046) 3

• A randomized controlled trial in perforated appendicitis showed DPC reduced wound infection rates from 38.9% to just 2.9% (p<0.001) 4

Clinical Applications and Considerations

DPC is particularly beneficial in:

• Contaminated abdominal surgeries (Class III and IV wounds)
• Perforated appendicitis
• Traumatic contaminated wounds
• Resource-constrained environments where infection risk is high

Important Caveats:

• DPC requires additional patient visits for wound closure
• May increase initial length of hospital stay (1.6 days longer in some studies) 1
• Cost considerations vary by healthcare setting (primary closure was found to be less expensive in some studies) 1
• The technique requires proper wound assessment to determine optimal timing for closure (typically 3-5 days) 5

Modern Approach to DPC

Current evidence suggests that DPC remains valuable in specific scenarios:

• While some meta-analyses show mixed results when using random-effects models 1, the most recent high-quality studies continue to support DPC for contaminated wounds
• Negative pressure wound therapy combined with DPC has shown promising results in further reducing infection rates 3
• The World Journal of Emergency Surgery guidelines suggest DPC may be preferable in contaminated abdominal surgeries, especially in high-risk patients 1

In summary, delayed primary wound closure promotes increased angiogenesis and granulation tissue formation, which provides a better foundation for wound healing in contaminated surgical sites, making option (a) the correct answer.