I wouldn't take her if it's going to make it a stressful experience for you. I don't really think scans are all that exciting, to be honest, and mine is nearly 5 and I don't think she'd really get it or enjoy it. I think not knowing what she's missing, she would probably be just as excited to have you come back and show her the pictures and talk about the baby and what you saw. They can pick up on things if you're nervous and stressed and she will likely sense something is wrong. I wouldn't want to make it a stressful experience for her. I wouldn't take my daughter to any scans, I don't think, unless it was purely a childcare related issue and I couldn't leave her with anyone else. I think I would want to feel as relaxed as possible for it all and I think I would be more on edge if my daughter was there, which is seems like you would too. I also know mine is very hopeful for a particular gender (she really wants a brother), so I would want to tell her privately and not in a scan room just in case I wasn't sure how she would react.