Final answer:
The characteristic feature of caput succedaneum in newborns is an edematous area on the scalp that crosses suture lines, typically resolving on its own within a few days after birth.
Step-by-step explanation:
The characteristic feature of caput succedaneum in newborns is that it is an edematous area on the scalp, usually resulting from prolonged labor, and it crosses suture lines.
Caput succedaneum refers to swelling or edema of a newborn's scalp that appears as a soft, puffy area, which develops as the baby travels through the birth canal. This swelling can cross cranial suture lines, differentiating it from cephalohematoma, which does not cross such lines.
Since the skull bones of newborns are not fully ossified and are separated by areas filled with fibrous connective tissue called fontanelles, there's a flexibility to the skull that helps the baby's head pass through the birth canal during birth and allows for growth of the skull after birth. The condition of caput succedaneum typically resolves on its own within a few days after birth without causing harm to the infant.