**Core Concept**
Caput succedaneum is a form of edema that occurs in the scalp of newborns, typically due to the pressure exerted by the vaginal walls during delivery. It is characterized by the accumulation of fluid in the loose connective tissue of the scalp, leading to swelling and blistering. This condition is benign and resolves on its own within a few days.

**Why the Correct Answer is Right**
The characteristics of caput succedaneum include:

* Bilateral involvement, as the pressure exerted by the vaginal walls affects both sides of the scalp
* Presence of ecchymosis, which is a result of the breakdown of blood vessels and the release of hemoglobin into the surrounding tissue
* Absence of a well-defined border, as the edema spreads across the scalp
* Association with vaginal delivery, particularly with forceps or vacuum-assisted delivery

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because caput succedaneum can occur even in the absence of trauma, making it a distinct entity from cephalohematoma, which is caused by trauma to the skull bones.
* **Option B:** This option is incorrect because caput succedaneum is not limited to the parietal region, but can occur in any part of the scalp.
* **Option C:** This option is incorrect because caput succedaneum is not a result of infection, but rather a benign condition caused by fluid accumulation in the scalp.

**Clinical Pearl / High-Yield Fact**
Caput succedaneum is a self-limiting condition that resolves on its own within a few days, but it can be a useful diagnostic clue in differentiating it from other conditions such as cephalohematoma or subgaleal hemorrhage.

**Correct Answer:** A.