I haven't had this particular experience, but we were told our baby had moderate ventriculomegaly (fluid on the brain) at a 29-week scan. We had more scans, an MRI and the option to have an amnio and genetic counselling etc. We refused the latter two (as my down to earth doctor told me I'd potentially cause more harm to the baby through an amnio and better just to wait and see).
I have very mixed feelings about late scans, as for a few weeks, my pregnancy was enormously stressful, and yet when our baby girl was born, the ventriculomegaly had completely disappeared, and she was perfectly healthy (and is now developing completely normally at 20 months).
So I guess what I'm trying to say is try to relax (although i realise that probably comes across as trite), and that babies all develop differently in the womb, and what may seem abnormal may just be within a range of normal.
In the last few weeks after we'd had all the scans, MRI etc, I somehow managed to put it to the back of my mind (helped, i think, by hypnobirthing CDs!) and while I always had a niggling worry that there would be something wrong with our baby, I knew there was nothing I could do until the birth.
Fingers crossed that all goes well for you.