ER visits during pregnancy

I nearly didn't go to the ER for a threatened miscarriage because all I've seen on here is people telling each other not to go to the ER for this. But when I got to the ER I was told repeatedly that during pregnancy if there is a lot of bleeding or really bad cramping, I need to go to the ER. There's always more possibilities to a miscarriage than simply waiting it out at home. Some are ectopic and need more care, if your blood type is negative and the dad is positive you'll need a rhogam shot, and if the miscarriage only is a partial then they'll talk about a D&C. But I was repeatedly told, ER is the place to go for lots of bleeding and pain during pregnancy if you cannot get to your ob right away.