In a 1400 g neonate, the maximum volume for an intramuscular injection in the anterior thigh should not exceed how many milliliters?

• A. 0.5 mL
• B. 1.0 mL
• C. 0.25 mL
• D. 2 mL

Answer: (A)

The amount you can safely give into a neonate’s muscle is limited by how small the muscle is and the need to ensure true intramuscular deposition in the viable muscle tissue. For an infant weighing about 1.4 kg, the anterior thigh (vastus lateralis) is the preferred IM site because it provides the most muscle with minimal risk to nerves and vessels.

Because of the tiny muscle mass, the maximum per injection is about 0.5 mL. Exceeding this volume can overdistend the muscle, increase the chance of injecting into subcutaneous tissue rather than deeply into muscle, and raise the risk of local tissue injury, pain, or unreliable absorption. Therefore, 0.5 mL is the upper limit for a single IM injection at that site in a neonate. If a larger total dose is needed, it should be divided into multiple injections at separate sites or administered by another appropriate route.