I've had 2 missed miscarriages. It's the term used when the baby miscarries, but the body does not expel it. It's not the same as a chemical pregnancy, and if the foetus comes away, that's a 'regular' miscarriage. The way you find out is either a bleed, followed by a scan to check the baby is ok, or a usual scheduled scan. The first of mine was my 11 week scan, the second I had a bleed at 10 weeks followed by a scan to check. In both cases the baby had stopped growing 3-4 weeks earlier but my body had held onto it. I needed a D & C both times.
Hope this helps xx