How can you tell the difference between menstrual blood and implantation bleeding? what if you used a condom that didn't break or slide off?

About implantation..: Only after a positive preg. test can tell a woman that PRIOR spotting was actually implantation bleeding. It can be hard to tell if a woman is pregnant because some of the symptoms seen in early pregnancy can also happen in non-pregnant women. A urine pregnancy test gives a reliable result about 3 weeks after sex (3 weeks after when conception might have occurred) or 1 week after missing a period.