The most common site for an intramuscular injection in an infant is the:

BTSC 3 August 2025

Nursing Foundation

Easy

Appeared in: BTSC 3 August 2025

Explanation

The vastus lateralis muscle, located on the outer thigh, is the recommended and most common site for intramuscular injections in infants (birth to 12 months).
This muscle is well-developed even before an infant begins to walk, providing a large and safe area for medication administration.
It is free from major nerves (like the sciatic nerve) and blood vessels, which significantly reduces the risk of injection-related injuries.
It is the standard site designated by the CDC for routine immunizations in infants and toddlers.

Option A: The deltoid muscle in the upper arm is too small and underdeveloped in infants to safely accommodate an IM injection. Using this site increases the risk of injuring the radial nerve or the humerus bone.
Option B: The dorsogluteal site is contraindicated for infants and young children. It poses a significant risk of damaging the sciatic nerve, which can result in permanent paralysis or foot drop.
Option D: While the ventrogluteal site is a safe option free from major nerves, it is not the most common site for infants. The landmarks can be more difficult to identify accurately on a small infant compared to the vastus lateralis.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pediatric Intramuscular Injection Sites as background academic context rather than a clinical decision trigger.
Correct site selection for IM injections is a fundamental patient safety competency for nurses to prevent serious complications like nerve damage, abscesses, or bone injury.
Nurses must educate parents about the chosen injection site and the importance of following immunization schedules to promote adherence and reduce parental anxiety.
What if? If an infant has a cast on the left leg or a localized infection over the left vastus lateralis, the nurse should use the vastus lateralis on the right leg. If both legs are inaccessible, the ventrogluteal site would be the next best alternative, but this should be performed by a practitioner confident in locating the site on an infant.

How to Approach the Question

First, identify the key information in the question: the procedure is an 'intramuscular injection' and the patient population is an 'infant'.
Recall the developmental anatomy of an infant. Infants have underdeveloped muscles in their arms (deltoid) and buttocks (gluteals) because they are not yet walking.
Consider the safety of each site. Eliminate the dorsogluteal site immediately due to the high risk of sciatic nerve injury.
Eliminate the deltoid muscle because it is too small in an infant.
Compare the remaining two safe options: vastus lateralis and ventrogluteal. The vastus lateralis (thigh muscle) is the largest and most developed muscle in an infant, making it the safest and most common choice for routine injections and immunizations.
Therefore, select the vastus lateralis as the most appropriate answer.

Concept Tested & Keywords

Concept Tested: Pediatric Intramuscular Injection Sites
Stem keywords: intramuscular injection, infant
Lead-in keywords: most common site
Clinical cues: The patient's age (infant) is the most critical factor in determining the correct injection site.

QGtdnb0PkASLRHfkOb9Oeo

E6 Nursing Fundamentals Potter Perry 12e Part 3 pp. 174-176, 175-177

E6 Nursing Fundamentals Taylor p. 861-863