So, if you happen to be engorged, or you have a plugged duct and you're not around your baby, using a breast pump is your best option. With the engorgement, it's going to be very similar to if you're engorged and you do have the baby there, you still need to get some ice packs on there. You still need to massage before hand, and then you can pump after that.
With a plugged duct it's going to be very similar, although you will usually find with a plugged duct that you will feel a little ball, a little hard knot in the breast. You'll feel the plug and I always recommend massaging just that area at the same that you're pumping, in order to clear the clog. That will really help. And also at the same time that you have the pump on, you're going to want to put maybe some local heat on a plugged duct, but not on the engorged breast.