Yes, they usually do have the volume listed on the bag, but I've had many experiences where the amount was wrong. I've always cleared the volume on the pump before the start of the infusion, so that when it's done, I will know how much went in. Ex. I had a bag one time that said it had 250mL, but the bag was FULL, I thought "No way." Sure enough, wound up infusing 512 mL off that one bag, and I made sure I let the doc know when it was done (was supposed to be the 1st of 3 transfusions). He had us get h/h after that one, and she was good