I am sorry to hear this, but I just went through this same thing with my now 4 month old daughter. She had this same thing and they said it could be a few different things...CF, down syndrome, and some other type of infection that was testable by bloodwork (can't remember the name of it, but it ended up not being...something you can get from like changing the cat litter and stuff), or they said it could be nothing. We already had one with CF, so we figured it was the CF, but could not be positive without amnio or birth/testing. I opted out of amnio due to the risks, and the fact that I was pretty much sure it was CF since out last had a bowel blockage (which was not caught by ultrasound).
She had surgery and a bit of a long NICU stay, but is now home and happy with us! She is a handful with many meds right now, but we are so happy to have her home!
Just make sure you will have the doctors necessary for any complications right after delivery. The worst is to have your baby moved to another hospital when you have to stay at the one you deliver at. Experienced that with my first. Made prearrangements to deliver elsewhere for the second. Also make sure they monitor that bowel to avoid it bursting. Mine was 5 1/2 weeks early due to no movement (ambilical around neck at emergency c-section). They said if she had stayed in much longer, the bowel may have burst and things could have been much worse than they were.
I wish you guys the best and hope you keep us updated. PM me if you have any questions.