Hi J. - What a difficult thing to hear! I can understand how upsetting this would be, and it doesn't sound like your ob-gyn gave you very good information. I hope you are doing ok. I have no personal experience with this, but I did some reading online, and found that in 65.5% of cases, an echogenic bowel does not really indicate any clear problem at all. So in 2/3 of cases, the baby is born healthy and ok, and actually, in most of the other cases, it is either something treatable (like an infection), or challenging but manageable (like Downs syndrome). You can take heart in that.
Echogenic means that the bowel is bouncing back the ultrasound waves just as well as the bones and other hard structures typically do. Usually the bowel shows up as a dark area in the u/s, because it is just soft tissue that is hollow inside. But blood is very echogenic, because of all the iron in it. It makes the bowel show up more.
If you had an isolated incidence of bleeding into your amniotic fluid (which can happen for a lot of reasons), it can take up to 3-4 weeks for that to go away. I would imagine they want you to have a repeat u/s in 2 weeks just to make sure that the bleeding is not continuing. The blood itself cannot harm your baby in any way!
This is the website I got good research-based information from. It's pretty technical, but I would be happy to help if any of it is confusing. Just message me!
http://www.fetalultrasound.com/online/text/2-042.htm
I'll be over here wishing for the best outcome for you and your little one. Read up on it.