I think getting a drug without your consent is an unlikely occurrence in a hospital. And if anyone ever does, you can sue them within an inch of their lives.
That is, unless, the woman doctors the form and writes "subject to my informed consent at the time" prior to signing. Or, if the nurse throws a hissy and wants her to sign the form "as is" the woman can do that and then after getting checked in she can hand over another paper saying "I hereby withdraw my consent unless I explicitly give my informed consent at the time a medical procedure is offered." They can't kick her out so they'll just have to deal.
I love that quote about the paramedic and IV.