Final answer:
In the case of an umbilical cord protrusion during labor, the nurse should elevate the client's hips to reduce cord compression while waiting for emergency medical assistance.
Step-by-step explanation:
If a nurse observes the umbilical cord protruding from the vagina during labor, the correct action to take after calling for assistance is to elevate the client's hips. This is known as the Trendelenburg position or a knee-chest position, which aims to relieve the pressure on the cord and decrease the risk of cord compression, which can jeopardize the baby's oxygen supply. It is crucial not to push the cord back into the vagina or encourage the client to push, as this could worsen the situation. Placing the client in a supine position with the head elevated is also not recommended because it does not alleviate the pressure on the umbilical cord. Immediate medical intervention is necessary to resolve this obstetric emergency.