Enlarged Ventricles?

JSS
I had the anatomy scan today....ventricle measured 12mm, which is slightly out of range. The norm is 10mm. I didn't have the genetic testing done earlier on, but they drew blood today, and I'm scheduled next week for a fetal MRI. They said there does not appear to be excess fluid which is good, and the rest of the scan was great. No heart issues, bowel issues, or signs of deformity. They should have a better idea of what's going on after the MRI and test results come back. Has anyone experienced this? The doc  said it often times is nothing, and they just monitor the growth throughout the pregnancy. She said she feels confident that it's nothing serious based on the rest of the scan, but I'm terrified.