Certified Medical Assistant (CMA AAMA)PharmacologyEasy
A medical assistant is preparing to administer an intramuscular injection to an adult patient. Which of the following needle gauges is most appropriate for a standard intramuscular injection?
- A20 gauge
- B25 gauge
- C18 gauge
- D27 gauge
Show answer & explanationAnswer & explanation
Correct answer: B. 25 gauge
For most standard intramuscular injections in adults, a 25-gauge needle is appropriate. It is thin enough to minimize discomfort but strong enough to penetrate muscle tissue.
Why the other options are wrong
- A. 20 gauge is thicker and might be used for highly viscous medications or larger muscles, but 25G is generally preferred for standard IM.
- C. 18 gauge is a very thick needle, typically used for drawing up medications or for very viscous solutions, not routine IM injections as it would cause unnecessary pain.
- D. 27 gauge is too small for most IM injections and is typically used for intradermal injections.
IM Needle Gauge
Needle gauge refers to the diameter of the needle. For intramuscular injections, the gauge is selected based on the patient's size, medication viscosity, and injection site.
- Higher gauge number means a thinner needle.
- Common IM gauges are 20-25 gauge.
- Thinner needles (higher gauge) cause less pain.
Memory trick: Gauge, Go, Get Good Muscle