Pre-filled saline syringes and checking central line blood return

You make a good point, then of course that entails dropping the syringe onto a sterile field giving you time to put on your sterile gloves to maintain sterility of the outside of the syringe. I can't see that happening on a regular basis outside of surgery, or the for the syringes which come in the setup kits for certain procedures done on the floors.

You are correct. I bet it doesn't happen much.

I think the point here is, you maintain the most sterile enviroment that you can. I firmly believe that nothing is 100% sterile. Once it has been exposed to air, (regadless of negative pressure, etc), some microorganisms
will contaminate the surface.

This issue came up for us many years ago when these syringes became popular. The one way in which it did change my practice was when I was accessing ports. I used to be able to draw up the saline flush from a vial with one hand ungloved and the sterile gloved hand holding the sterile syringe and then set the syringe back onto my field and then apply my second sterile glove. Now I have to scoot the extension tubing while in the package to the edge of the wrapper and only pick up the sterile gripper when I am ready to access. We also make sure we do not place them on any sterile field as when in placing a midline,PICC or CVC as only the fluid and fluid pathway is sterile. I can assure there is no contraindication in using the pre-fills with and VAD. The risk of using using vials,other than for one time use poses a much greater risk for CVC-related infections and bloodstream infections.

I think I understand. Original post is asking about sterility of the inside of the barrel when the part you use to push the med in (the "stem" of plunger. . .?) is touched? in clinical lab we were told NEVER TOUCH THAT PART because if you are drawing a med which requires you to pull back and then you push the med, the "contaminated" stem goes back into the barrel area, and if you had to push and draw a couple of times to get med ready, then you could contaminate.

However, once in the real world I learned this was ridiculous and nobody had ever heard of that (ah, clinical skills lab!). A nurse could not function if that were true!

Small note about mixing meds in prefilled syringe. . .
I personally use one of our provided empty syringes to draw the med, and then draw from NS from the prefilled into the other syringe if I need dilution. I do this so when I walk into the room the syringe with the med in it LOOKS DIFFERENT than my flushes. Some meds I would NOT want to accidentally forget and push like a flush. I use a sharpy and label my syringe too, but I like things to be as different looking as possible! Maybe it's "new nurse paranoia", but it makes me feel better