Should I be a worried mommy? Brain scan

So today we had our 19 week scan. Everything was good with our wee man but they measured "the part of his brain that stores and makes spinal fluid" and it is a bit big. It is measuring at 20 weeks 1 day and babes is 19 weeks 5 days. They are sending our scans to the specialist team and we will have to get more scans but I have no idea what to expect or what that means. I'm so worried. Anyone else have any similar experience or information? ? Please help me