Final answer:
The appropriate nursing action after noticing a newborn's head is not symmetrical with a chignon over the posterior fontanelle following a vacuum extraction delivery is to document and continue routine observation.
Step-by-step explanation:
The appropriate nursing action after noticing a newborn's head is not symmetrical with a chignon over the posterior fontanelle following a vacuum extraction delivery is to document and continue routine observation. This means that the nurse should carefully monitor the newborn's head for any changes or signs of improvement. It is important to note that in most cases, the swelling will resolve without treatment.