Cephalohematoma is a subperiosteal hematoma, limited by suture lines, that usually develops after delivery using instruments. The periosteum of the involved bone, usually parietal or occipital bone, is elevated by the underlying hematoma. There are usually no associated skull fractures and they resolve on their own. Large cephalohematomas may occur with vitamin K deficiency in the newborn.

Swelling of the scalp may also be seen with caput succedaneum (subcutaneous edema and/or hemorrhage) and subgaleal hemorrhage (subaponeurotic hemorrhage). These conditions are more superficial and extend more widely over the skull because they are not limited by the attachments of the periosteum.