As an RN in Calif..a nurse could do fills
IF they worked with the Bariatric Center and
IF they went thru a training program and demonstrated competency and
IF there was what is called a "standardized procedure" in place at the Bariatric Center. (the reason is because this would be considered an "advanced practice" type of procedure)
In my line of work RN's perform "advanced practice" procedures all the time, BUT under very strict guidelines (the standardized procedures). I work in neonatal intensive care and we place Umbilical Artery Catheters, Umbilical Venous Catheters, Intubate and other things that I would consider more complicated than a fill, we do have to demonstrate our competency on a yearly basis and maintain it and the hospital keeps these records.
So it is feasable that an RN could be taught the procedure but there are hoops to jump thru. An advanced practice nurse....(a Nurse Practitioner) would not have as many hoops, as this would be under thier scope of practice, but they would still have to have competencies documented. And as the NP above noted, they would have lower reimbursement.
As far as the medical assistant doing this...RUN AWAY AS FAST AS YOU CAN!

I WOULD NEVER LET AN MA DO THIS,

in CA they cannot do this, period, trained or not, as it is an "invasive" procedure. RUN, FOREST, RUN!
B