Invited for Obstetrics appointment what is this?

So I have been invited to a Obstetrics appointment at the hospital in a few weeks. I have no idea what this is and just wondered if any other mummas to be or now mum's had this appointment and could tell me what it is and is all about. I'm 22w 1d today and at time of appointment will be 23w 5d. At my last scan (20w) they found out I had an anterior placenta low but I was offered another scan at 32w to see if it had moved. Was wondering if this appointment is about that?? It's got me concerned that they have found something more sinister with my baby?? Sorry for long post I'm a FTM and advice would be appreciated