Midwife couldnt find baby heartbeat!!!

Jenna

I just went for a routine midwife appnt, I'm just past 13 weeks, midwife couldn't find baby's heartbeat with doppler so am going in for a scan this afternoon. I had my 12 week scan just 3 days ago & all was fine with HR of 155. Has this happened to anyone else?? What was the outcome?? I anxiously awaiting scan & hoping baby was just difficult to find with doppler.