A nurse is reviewing laboratory results for a newborn who received vitamin K injection at birth.

Which of the following coagulation factors should be activated by vitamin K?

The correct answer is choice B. Check if there is any cross-sensitivity between erythromycin and penicillin.Erythromycin is a macrolide antibiotic that can be used to treat bacterial eye infections in newborns and adults.

Penicillin is a beta-lactam antibiotic that can cause allergic reactions in some people.

Cross-sensitivity means that a person who is allergic to one type of antibiotic may also be allergic to another type of antibiotic that has a similar structure or mechanism of action.Erythromycin and penicillin have different structures and mechanisms of action, but there is still a small chance of cross-sensitivity between them.

Therefore, the nurse should check if the newborn has any history of allergic reaction to penicillin before applying the erythromycin eye ointment.

Choice A is wrong because asking the mother if she has any allergies to antibiotics is not enough to determine if the newborn is at risk of an allergic reaction to erythromycin.

The newborn may have inherited or developed an allergy to penicillin or erythromycin that the mother does not have.

Choice C is wrong because applying a small amount of ointment on the skin to test for allergic reaction is not a reliable method to diagnose an allergy.Skin testing can cause false positive or false negative results, and it may also trigger a severe allergic reaction in some cases.

Choice D is wrong because administering an antihistamine to prevent anaphylaxis is not appropriate for a newborn who has not been exposed to the allergen yet.

An antihistamine is a medication that blocks the effects of histamine, a chemical that causes allergic symptoms.

Anaphylaxis is a life-threatening allergic reaction that involves multiple organ systems and requires immediate medical attention.An antihistamine cannot prevent anaphylaxis, and it may also cause side effects such as drowsiness, dry mouth, or low blood pressure in a newborn.

The correct answer is choice A.Washing hands before and after handling the cord stump can prevent the transmission of bacteria that can cause omphalitis, sepsis, and tetanus.

Choice B is wrong because applying petroleum jelly or ointment to the cord stump can delay its drying and increase the risk of infection.

Choice C is wrong because using hydrogen peroxide to clean the cord stump can damage the healthy tissue and delay healing.

Choice D is wrong because folding down the diaper below the cord stump can expose it to urine and feces, which can contaminate it and cause infection.

The normal range for umbilical cord separation is 5 to 15 days after birth.