Unused and used syringe needle comparison - GIF

[wjzemke1968]

Hello,
Thank you for the post concerning the microscopic view of an injection needle.

I am a retired clinical pharmacist, retiring in 2014 after having practiced hospital pharmacy for 50 years. During my career, i had a similar experience with a family of injectable products which were repeatedly traumatizing patients. All of the trauma occurred post injection and all during the withdrawal phase of the injection process. (i.e. During the insertion phase of the injection a normal amount of discomfort was experienced, but upon withdrawal of the needle a large amount of pain was experienced.) Upon inspection of the needles under the metallurgical microscope, similar "barbs" to those in the post were found on the needles causing the pain. Upon further inspection of new, unused needles more barbs were also found. Essentially the nurse giving the injection was doing so while unknowingly using a barbed fishhook rather than a hypodermic needle. No wonder it hurt!!! This points away from physical alteration of the needle geometry during injection as suggested. What is much more likely is that this represents a manufacturing defect, and could be related to the metal used in the needle, the abrasive used to sharpen he needle, and the sharpening parameters and conditions among other factors. The primary reasons that needles should not be reused are those of infection control. In other words, once a needle goes into a muscle, it becomes contaminated, is no longe sterile, and therefore unsuitable for reuse in ANY patient including the one that its just came out of.

Hope that this helps to clarify some things.

W. John Zemke, Pharm. D.