This may seem completely irrelevant but I remember when my friend used to lay on her bed, we were 15 years old at the time & you could see the pulse in her stomach! I could be wrong but I dont think it has anything to do with being pregnant, maybe we can feel it a little stronger, Im not sure but I doubt very much it will affect your scan! you should have a 16/17 wk appointment with your midwife, mention it to her if you're still worried! Hope Ive helped a little!! Marie x