Hey, sorry, I haven't been around in a bit. The usual size needle is a 20G for IVIG. Is hard to explain the needle sizes. Ummm if you have been to the ER you probably have had an 18g needle inserted. *standard ER protocol in case you were to need blood* trying to think how to splain, LOL. Have you had your blood drawn with a vacutainer (a needle on the end of a plastic sleeve that they push the tubes into one by one) Well that is probably closer to 18 than 20 (0ddly the smaller the number the bigger the needle) and the size is not in length, that is a whole nuther thing altogether. The gauge is the diameter of the lumen or the inside of the needle. IVIG is very thick and sticky thus the need for a bit larger than usual. A good size for most people is a 22g but the 20 is better for the ivig viscosity.
Does any of this make sense or did I just confuse you even more??