Where should a nurse administer intramuscular phytonadione 0.5 mg to a newborn?

Administering intramuscular phytonadione (vitamin K) to a newborn is typically performed in the vastus lateralis muscle, which is located in the outer thigh. This muscle is preferred for several key reasons.

Firstly, the vastus lateralis is well-developed in infants and is large enough to accommodate the injection, allowing for proper absorption of the vitamin K. Secondly, it is a safe site for injection because it is remote from major nerves and blood vessels, reducing the risk of complications associated with intramuscular injections in sensitive pediatric populations.

Choosing this site helps ensure that the vitamin K is delivered effectively, which is crucial for newborns who are at risk of vitamin K deficiency bleeding due to their immature liver function and low levels of vitamin K at birth. The rectus femoris and deltoid muscles are less commonly used in infants due to size limitations, and the gluteal muscle is avoided in newborns due to the risk of injury to the sciatic nerve and other structures. Thus, targeting the vastus lateralis is the most appropriate and safest choice for this specific population.