In medicine, a needleless connector connects to the end of vascular catheters and enable catheter access for infusion and aspiration.^[1] Needleless connectors (also known as NC's) were developed to reduce needlestick injuries, which occurs when the skin is accidentally punctured by a used needle.^[2] Needlestick injuries can be very serious and potentially expose a healthcare professional to bloodborne infectious diseases such as HIV/AIDS, Hepatitis B and Hepatitis C.^[3][4]

The needless connector should provide safe access to the catheter without the use of needles and enable the following:^{[citation needed]}

• Minimize catheter occlusion risk.
• Allow for easy and effective decontamination between each use to prohibit microbial entry e.g. via a flat surface which is flush with the housing.

Before utilizing a needleless connector, it is important to properly disinfect the device to help prevent central line^[5]–associated bloodstream infection.^[6]

Various designs for the needless connector and its components have been developed over the years. This includes a patent developed by Karl Leinsing for "needleless connector" which relates generally to connectors of the type used in the handling and administration of parenteral fluids, and more particularly, to a valve mechanism incorporated within such connector for~~enabling a fluid interconnection to be made therewith without the use of a sharp cannula.^[7]