Can doctor tell if implantation spotting or an early miscarriage after 3 wks? been 3 wks since spotting & still no positive hpt:(

Miscarriage unlikely: A woman has to be pregnant first, in order to lose the pregnancy through miscarriage. Miscarriage is a natural end to many pregnancies (often because it is nature's way of selecting out abnormal embryos or fetuses, and trying to let only the normal ones continue on to birth). That means the pregnancy test would be positive if a miscarriage were to happen.