Does Either Scratching Or Open Blistering Of Poison Ivy/sumac Spread

Does either scratching or open blistering of poison ivy/sumac spread the rash? Everything I have ever read or heard says no, but my doctor says yes. I understand that if the oil is left somewhere and touched on the skin it can look like it's spreading but, that's not the same as the fluid in the blisters. (I just received a shot and some oral meds and ointments for my rash today, but now am concerned that the rash could pass on to my family).
Thanks!