NHA Certified Clinical Medical Assistant (CCMA)Clinical Patient CareHard
A medical assistant is preparing to administer an intramuscular (IM) injection to an adult patient. Which of the following needle lengths and gauges is most appropriate for a deltoid muscle injection in an average-sized adult?
- A5/8-inch, 23-gauge
- B1.5-inch, 21-gauge
- C1-inch, 25-gauge
- D2-inch, 18-gauge
Show answer & explanationAnswer & explanation
Correct answer: C. 1-inch, 25-gauge
For an average-sized adult receiving an IM injection in the deltoid, a needle length of 1 to 1.5 inches is typically used to reach the muscle tissue, and a gauge of 22-25 is appropriate for most medications. A 1-inch, 25-gauge needle fits these criteria well, balancing efficacy with patient comfort.
Why the other options are wrong
- A. A 5/8-inch needle is generally too short for an IM injection in an adult deltoid; it would likely result in a subcutaneous injection.
- B. A 1.5-inch needle might be too long for an average adult's deltoid, potentially hitting bone, and a 21-gauge is larger than usually necessary, causing more discomfort.
- D. A 2-inch needle is excessively long for a deltoid injection in an average adult, and an 18-gauge is too large, typically reserved for viscous medications or rapid fluid administration in larger muscles like the gluteal.
IM Deltoid Needle Selection
For intramuscular injections into the deltoid muscle of an average adult, a 1-inch to 1.5-inch needle length and a 22- to 25-gauge needle are typically recommended to ensure proper muscle penetration while minimizing discomfort.
- Deltoid site for IM injections.
- 1 to 1.5 inch length for adults.
- 22 to 25 gauge for most medications.
Memory trick: Needle Length for Muscle: Deltoid is One, Glute is One-Five.