Can I miscarry from having small subchorionic hemorrhage and no bleeding?

I got an ultrasound today because I was cramping really bad. And the doctor said i had subchorionic hemorrhage the size is 2.9cm. And I'm 4weeks and 6days. Will I miscarry or will it clear up on it's on. I'm nervous. And is it normal to not see a fetal pole and yolk sac at 4weeks 6days