How long can I use a pregnancy test to detect pregnancy?

about two weeks in the same room can use pregnancy test stick to detect whether urine pregnancy, under normal circumstances in the same room after 7-10 days can go to the hospital to draw blood, check HCG in the blood to judge whether pregnant, after pregnancy there is a kind of hormone called human chorionic gonadotropin in the blood, when it reaches a certain level urine will also contain a certain amount of HCG, this time with early pregnancy test paper to detect or pregnancy test stick urine will present a positive reaction. However, HCG positive reaction in urine is much later than that in blood, so for those who are anxious to know the results, go to the hospital to take blood to check HCG, only blood or urine HCG positive, ultrasound examination shows embryo and primitive cardiac pulsation, in order to diagnose normal early pregnancy.