What gauges of needles are used for different medical procedures?


What gauges of needles are used for different medical procedures?
Needle gauges vary depending on the medical procedure and the type of fluid being injected or withdrawn. The gauge refers to the diameter of the needle — the higher the gauge, the thinner the needle. Here's a general guide to common needle gauges and their uses:
Common Needle Gauges and Uses
Gauge |
Needle Diameter (approx.) |
Common Uses |
|
18G |
1.2 mm |
Blood transfusions, rapid fluid infusions, needle size of choice for surgery |
|
20G |
0.9 mm |
General IV infusions, can be used for blood transfusions when larger needles cannot be inserted |
|
21G |
0.8 mm |
Routine blood draws, injections |
|
22G |
0.7 mm |
Pediatric/elderly blood draws, IM injections |
|
25G |
0.5 mm |
Intramuscular (IM) injections (thin patients), insulin, SQ injections |
|
27G |
0.4 mm |
Intradermal injections (TB test), Botox |
|
30G |
0.3 mm |
Insulin, allergy testing, fine injections |
General Rules of Thumb:
- Thicker needles (lower gauge) → used for thicker fluids (blood, viscous meds).
- Thinner needles (higher gauge) → used for comfort, small volume, or sensitive areas and for more irritating medications/fluids.
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