Hypodermic needle: Difference between revisions

The diameter of the needle is indicated by the needle [[Stubs Iron Wire Gauge|gauge]]. Various needle lengths are available for any given gauge. There are a number of systems for gauging needles, including the [[Stubs Iron Wire Gauge|Stubs Needle Gauge]] and the [[French catheter scale|French Catheter Scale]]. Needles in common medical use range from 7 gauge (the largest) to 33 (the smallest) on the Stubs scale. 21-gauge needles are most commonly used for drawing blood for testing purposes, and 16- or 17-gauge needles are most commonly used for blood donation, as the resulting lower pressure is less harmful to red blood cells (it also allows more blood to be collected in a shorter time).<ref>[http://www.iv-therapy.net/node/512 Blood Transfusions and Angio Size?] {{webarchive|url=https://web.archive.org/web/20160303232229/http://www.iv-therapy.net/node/512 |date=2016-03-03 }}</ref> Although reusable needles remain useful for some scientific applications, disposable needles are far more common in medicine. Disposable needles are embedded in a plastic or aluminium hub that attaches to the syringe barrel by means of a press-fit or twist-on fitting. These are sometimes referred to as "Luer Lock" connections, referring to the trademark [[Luer-Lok]].