Can you give any reurances regarding foetal alochol syndrome?

My girlfriend is really worried about the effects her drinking this weekend may have had. We've been trying for a baby for the last 3 months or so since having a miscarriage early in the year. My girlfriend has been virtually abstinent all of this time (just a gl or two of wine once a month). However, this weekend, convinced that her period was just about to start she went out twice with an old friend and drank much more heavily (I'd guess 10 units and 8 units). Yesterday we found that she is in fact about 5 weeks pregnant. She's been mortified all night and very worried about the damage she may have done. Will FAS show on scans at all? Will it increase likelihood of miscarriage? What is the chance some damage has been done? I'll filter answers to avoid upsetting her so be honest but I'd like to find some reuring messages.