How long do you hold IVF when drawing blood from PICC line?

Do you have to have an order to draw from a PICC line? It's been so long that I have forgotten.

I had 2 preceptors during my orientation - both of them didn't even bother to listen to lung sounds, unless the patient was admitted for something respiratory. And somehow, through the grace of God, they always charted that the lung sounds were clear. Amazing!

Is it necessary to waste 10 mL? When I worked MedSurg, we wasted 5 mL. It was the protocol, but now I wonder if that would mess with anything?
*Jess*

You're supposed to waste whatever you use as the flush. If you're flushing with 10cc, you should be wasting 10cc. Put it in, draw it out, then get "fresh" blood for the labwork.

What lab told me -- and it can depend on the test they are running, too -- is they want a 10 cc waste, especially if it's a heparinized line. If it's a saline locked PICC, 5 is okay. I always do 10, then look in the MAR to see if they are a saline or hep flush.