The thickness of the puncture needle is generally indicated by G
G（Gauge）
It is an internationally used ruler for determining the size of the needle. The larger the number of G, the smaller the outer diameter of the needle, i.e. the thinner the needle.
Note: G first emerged as a method of measuring the thickness of metal wires, especially iron wires. For centuries, the manufacturing process of wire was called "drawing". The process of making a thread starts with a thick wire and then makes a thin wire by drawing (or pulling) the wire through a gradually narrowing hole. Initially, the largest wire was named 1 G, and then, for each successive smaller caliber, the gauge number was increased by 1. Therefore, the smaller the wire, the greater the number of Gs.
The outer diameter of the needle decreases by 0.2 mm for each additional unit, e.g., 1.4 mm for 17 G, and 0.2 mm for each unit decreased, for 2 mm for 14 G. So for each increase in G, the caliber decreases by ≈11%. In general, G corresponds to the outer diameter of the needle (denoted in mm), while the inner diameter of the needle does not correspond to G. #护理专业 #护士 #护士懂护士
