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Ask a Fertility Nurse: Does Needle Gauge Make a Difference?

Image of Fertility Needle Gauge

by Gina Paoletti-Falcone, RN, BSN, Freedom Fertility Pharmacy, September 13, 2010


Does the needle gauge make a difference for my IVF injections? I love using the very small needle for the Lupron injection. Can I use small needles for my other injections, or must I use the big ones?

Nurse Gina Says:

Yes, needle gauge does make a difference, but the good news is that the majority of injections for IVF cycles are given with small needles. When we describe needles, there are two important numbers to consider:

Gauge: A measurement of the diameter or thickness of the needle. The bigger the number, the finer or thinner the needle.

Length: How long the needle is.

The gauge and length of the needle used for various medications is determined by the injection route. IVF medications are injected either subcutaneously (SC), in the fatty layer between skin and muscle, or intramuscularly (IM), directly into the muscle. Because the subcutaneous tissue is right below the skin, SC needles are thinner in diameter and shorter than IM needles that must go through the skin and subcutaneous tissue to reach the muscle layer. SC injections are usually given with 27-, 28- or 30-gauge 0.5 inch needles. IM injections are usually given with 21-, 22- or 25- gauge 1- or 1.5-inch needles. The needle may come permanently affixed to the syringe or may be able to be twisted on and off.

Some medications come from the manufacturer packaged with the syringes and needles to be used for administration. The leuprolide acetate (Lupron) two-week kit is an example. Leuprolide acetate comes in a pre-mixed multi-dose vial with syringes that have 28-gauge 0.5 inch needles affixed for SC injection. The Follistim and Gonal-f pens come with a supply of the 29-gauge 0.5-inch needles that must be twisted onto the pen before each use. The Gonal-f Multi-Dose vials come with syringes with 27-gauge 0.5-inch needles affixed. Several medications (ganirelix acetate and Ovidrel) come in prefilled, one-time use syringes with a 27-gauge 0.5-inch needle affixed.

There are other medications used in IVF cycles that require mixing a diluent with powdered medication to make a solution that can be drawn up and injected (examples include Menopur, Repronex, Novarel and HCG). In this case your nurse will order the appropriate syringes and needles for you to use. In general you will use a 3cc syringe with a 22-gauge 1.5-inch needle to do the mixing and drawing up so you have both the length and diameter to make it easy to move liquid into and out of vials and syringes. If you are then instructed to do an IM injection, you can simply leave that same needle on for the injection. If you have been instructed to do a SC injection, you will twist off the long mixing needle and twist on a 28- or 30-gauge 0.5-inch needle to do the injection.

Finally, there is progesterone in oil for IM injection. This comes in a 10 ml multi-dose vial with needles and syringes ordered separately. Because the progesterone in oil is thicker than the water based medications, some nurses order 18 gauge 1.5 inch needles to withdraw it from the vial. That’s a scary needle to look at because it’s pretty thick. But don’t worry, there will be a 21-, 22- or 25-gauge 1- or 1.5-inch needle for you to change over to do your injection.


Gina Paoletti-Falcone, RN, BSN is a graduate of Northeastern University and has worked in Women’s Health since 1978. In 2004, Gina joined Freedom Fertility Pharmacy as the Clinical Educator responsible for developing infertility educational content for employees, patients, nurse, and managed care plans in print and online. Gina writes a fertility blog on the Freedom Fertility Pharmacy website and enjoys educating and empowering patients to take an active role in their fertility treatment.