chemical pregnancies

so do any of you actually know what a chemical pregnancy is?? like the actual meaning of a chemical pregnancy? its a freaking miscarriage!!!! so me and my fiance experienced our very first miscarriage which would have been his first kid ever and the doc didn't even explain what a chemical pregnancy was I had to find out from my sister which experienced it and by researching it but my doc should have been the one to tell me what it was. like how do you go on just saying it was only some ones body's chemicals like why not just tell them before they find out after the fact and not even know what it actually was