Implantation bleeding usually is not bright red blood and if it is, it's not a lot. It's mixed with discharge. Although, if you are expecting a period, some girls can mistake it for being a short period.
Implantation bleeding is vaginal discharge which usually contains a small amount of pinkish or brownish blood. Only about a third of pregnant women experience implantation bleeding.
Unless accompanied by cramping, backache or increased bleeding, a small amount of blood being discharged should be considered as implantation bleeding which is nothing to be concerned about.
http://www.babyhopes.com/articles/implantation-bleeding.htmlWhat's implantation bleeding like; is it like a period?