She might see if she can get a referral for a perinatologist (high-risk OB). On my 18-week ultrasound my regular OB found a spot on my baby's bowel area, possibly indicating cystic fibrosis or chromosomal abnormality, so she referred me out to a perinatologist for a re-check. They tend to have better ultrasound equipment so sometimes can give you a better sense of what's going on, and they're specially trained in these sorts of issues.
Just so you know, the spot they found on the ultrasound that had us all panicking was totally gone on my first visit to the perinatologist, and I've had several follow-up ultrasounds that all indicate that she's cleared of it. Sometimes these things do resolve.
Sometimes issues like that resolve on their own that may be why they want them to wait. Personally I would request a specialist review the ultrasound. Good luck.