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Selecting Syringes and Needles

Selecting Syringes and Needles
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Most of us can recognize a syringe, with a needle sticking out of a long plastic body. For many, it is one childhood horror that they can never forget! But while your early years may have been spent dreading a needle, your teens or adulthood might require you to keep a supply of syringes ready for a doctor prescribed medication. When you start your own family, you may need a syringe supply for a family member to treat a medical condition. In this case, not only do you need to forget your old dread of this small medical device, but will also need to know how to use it. Most importantly, you need to know that not all syringes are the same, and that they are used for different purposes.

Anatomy of a Needle



Syringe and Needle Types

Syringes are available in several different designs and varieties. Most syringes are disposable and many come with an attached needle or with no needle at all. You may select the size of the syringe by the volume of medication it holds. Needles are selected by the gauge size and the length of the needle. Selecting the needle thicknesses and gauge, with varying needle lengths are entirely dependent upon where the injection is being administered. A very common type of syringe is the U-100 insulin syringe and needle used commonly for diabetic medications. It is for one time use only, and is thus, a very low cost syringe with needle combination. Below are images depicting the anatomy of a syringe and the anatomy of a needle.

Selecting the Right Syringe

Syringe selection is mostly based upon the volume of medication to be administered and the desired pressure flow. Volumes are usually measured in centimeters (cc) or milliliters (mL). Both types of measurements are equivalent in volume. A 1 cc syringe is the same as a 1 mL syringe. Large volumes of medication require larger syringe sizes. Lower pressure flows also require larger syringe sizes. The use of the syringe for injections, medical tubing or irrigation are also factors in syringe selection. Below is an infographic depicting the size of the syringe matched with the type of use for the syringe.

Common Types of Needles

Some of the most common needle tip styles include; the slip tip, eccentric tip, Luer lock and the catheter tip.

A Luer Lock tip syringe is the most commonly used, as its needle removal and installation is quite easy and quick. The twist mount helps secure the needle to the syringe for greater safety.

A slip tip syringe is also very commonly used and allows the user to merely push the needle hub onto the syringe. A catheter slip tip is used mostly used with medical tubing like catheters or feeding tubes.

Eccentric tips are used when you need to inject a medication parallel to the skin of the patient. It is also used when you want to inject into a vein on the surface, without the needle penetrating through both walls of the veins.

Two of the most common types of syringe needles include the Luer lock hub and the polypropylene slip hub. The Luer lock needle is only used with the barrel of a Luer lock syringe. The slip tip needle hub type is used with all other types of syringes available in the market. These syringes are made to easily slip over the tip of the barrel and become compressed for easy removal and installation.

Needle Thickness And Length Options

Needles vary in thickness and length. Short needles are used to inject something right underneath the skin, whereas long length needles are used to inject something into the body muscles.

Similarly, fine gauge needles are used to ensure less pain for the patient, while thicker gauges are meant for longer needles, and are used for thick skinned individuals. The viscosity of the medication is another consideration in needle gauge selection. The thicker the viscosity, the lower the gauge number. Gauge numbers are arranged so that the highest number represents smaller needle width while the lowest numbers represent the largest width. High viscosity medications would therefore use a wider width needle or a needle with a low gauge number.

Purchasing Syringes and Needles

When you buy syringes, it is very important that you know which one you actually need. Are you using the syringe with needle for intradermal injections, intramuscular injections or subcutaneous injections? The needle gauge and needle length selection is different for each type of injection. See the Needle Selection Continuum for Needle Gauge and the Needle Selection Continuum for Needle Length infographics displayed above. Below is a quick list of the selection criteria used for purchasing a syringe and needle.

  • Volume of medication to be administered determines syringe size.
  • Type of needle hub used determines syringe hub. (Luer Lock, Slip Tip, Eccentric Tip or Catheter Tip)
  • Viscosity of medication determines needle gauge.
  • Location of injection determines needle gauge and needle length.

Make sure you know your needs prior to shopping!