A nurse is admitting a client who is at 30 weeks of gestation and is in preterm labor. The client has a new order for betamethasone and asks the nurse about the purpose of this medication. The nurse should provide which of the following explanations?

Choice A reason: Obtaining a type and crossmatch is not the first action that the nurse should take, as it is a preparatory step for blood transfusion, which may or may not be needed. The nurse should first identify the cause and severity of the hypotension, and initiate immediate interventions to stop the bleeding and restore the circulation.

Choice B reason: Administering oxytocin infusion is not the first action that the nurse should take, as it is a pharmacological intervention that requires a prescription and an assessment of the uterine tone and bleeding. The nurse should first evaluate the firmness of the uterus and massage it if needed, to stimulate the contraction and retraction of the uterine muscle.

Choice C reason: Initiating oxygen therapy by nonrebreather mask is not the first action that the nurse should take, as it is a supportive intervention that aims to improve the oxygen delivery to the tissues and organs. The nurse should first address the underlying cause of the hypotension, which is most likely postpartum hemorrhage, and prevent further blood loss and shock.

Choice D reason: Evaluating the firmness of the uterus is the first action that the nurse should take, as it can help determine the source and extent of the bleeding, and guide the subsequent interventions. The nurse should palpate the fundus and check the lochia, and report any signs of uterine atony, which is the most common cause of postpartum hemorrhage.

Choice A reason: This statement is incorrect, as it describes the direct Coombs test, not the indirect Coombs test. The direct Coombs test is performed on the newborn's blood, and it detects the presence of maternal antibodies that have attached to the newborn's red blood cells. The direct Coombs test can help diagnose hemolytic disease of the newborn, which is a condition where the maternal antibodies destroy the newborn's red blood cells, causing anemia and jaundice.

Choice B reason: This statement is incorrect, as it is not the purpose of the indirect Coombs test, but rather a possible complication of hemolytic disease of the newborn. Kernicterus is a severe form of jaundice that occurs when the bilirubin level in the blood is very high, and it can cause brain damage, deafness, or death. Kernicterus can be prevented by treating the jaundice with phototherapy or exchange transfusion.

Choice C reason: This statement is correct, as it describes the indirect Coombs test, which is performed on the mother's blood, and it detects the presence of Rh-positive antibodies that have formed in response to the exposure to the Rh-positive blood of the newborn. The indirect Coombs test can help identify the risk of hemolytic disease of the newborn, and guide the administration of Rh immunoglobulin, which is a medication that prevents the formation of Rh-positive antibodies.

Choice D reason: This statement is incorrect, as it is not possible for the newborn to have Rh-negative antibodies, since the newborn has Rh-positive blood. Rh-negative antibodies are produced by Rh-negative individuals who have been exposed to Rh-positive blood, such as Rh-negative mothers who have Rh-positive newborns. Rh-negative antibodies can cross the placenta and attack the Rh-positive red blood cells of the newborn, causing hemolytic disease of the newborn.