You can view pictures, right?What damages are they going to sue for? What harm or potential harm has occurred? Patient was not checked on for 20 minutes? This is Texas, and the laws don't support such frivolous lawsuits like other states.
You want to find another transfusion center would be the easiest way to let them know your displeasure, and will hurt the business. Sorry about your sister, Benenglish, but I would keep the big picture in mind.
While not life threatening and hopefully not permanent, somebody should still be held accountable for negligence.
Like stated above, we don't really know if this is a common occurrence or once in a lifetime sutuation. But either way, somebody should have to answer for it.
Might be the nurse, might be their supervisor, might even be those that make the hospital policies.