**Core Concept**
Haemostasis in a scalp wound is crucial to prevent excessive bleeding and promote healing. The scalp has a rich network of blood vessels, making it a challenging area to achieve haemostasis. Effective haemostasis in the scalp is essential to prevent complications such as hypovolemic shock, infection, and scarring.

**Why the Correct Answer is Right**
Direct pressure over the wound is the most effective method to achieve haemostasis in a scalp wound. This is because the scalp has a loose areolar tissue that allows for easy compression of the underlying blood vessels. Applying direct pressure over the wound helps to constrict the blood vessels, reducing bleeding and promoting clot formation. This method is particularly effective in the scalp due to its rich blood supply and loose tissue, making it an ideal area for manual compression.

**Why Each Wrong Option is Incorrect**
**Option B:** Catching and crushing the bleeders by haemostats is not an effective method for haemostasis in the scalp. This method is more suitable for deeper wounds where access to the vessels is limited, and direct pressure is not possible. In the scalp, direct pressure is more effective and less likely to cause tissue damage.

**Option C:** Eversion of the galea aponeurotica is a surgical technique used to expose the underlying tissue, but it is not a method for achieving haemostasis. Eversion of the galea can actually increase bleeding by exposing the underlying blood vessels.

**Option D:** Coagulation of bleeders is a method used in surgical procedures to achieve haemostasis, but it is not the best method for scalp wounds. Coagulation of bleeders requires surgical intervention and is not as effective as direct pressure in achieving haemostasis in the scalp.

**Clinical Pearl / High-Yield Fact**
In scalp wounds, direct pressure should be applied for at least 5-10 minutes to ensure effective haemostasis. This is because the scalp has a rich blood supply, and it takes time for the blood vessels to constrict and promote clot formation.

**Correct Answer:**
✓ Correct Answer: A. Direct presure over the wound