If I had unprotected sex 8 days ago and my period is almost 3days late will the pregnancy show up this soon on a blood test?

Re do test. It takes the fetus about 3 weeks to make enough HCG for a positive pregnancy test. You may repeat the test at three weeks after sex, unless you get a period by then.
Possible. Although pregnancy tests are sesnsitive and realiable , during the first week of a pregnancy they can not pick up the pregnancy. You could try to check, but if the test is negative wait atleast a week then recheck.

Related Questions

I'm 46. My period which is normally regular is 2 weeks late. I had had unprotected sex 3.5 weeks ago. I have taken 3 pregnancy tests with negative on all 3. If I go to my Dr. Can they do a blood test to see if I'm pregnant or if I'm going through menopaus

Blood test will help. By doing blood test it's possible to differentiate between pregnancy, delayed period or menopausal changes. Though fertility generally declines with age, keep in mind that most unplanned pregnancies happen before 20 and after 40. Use of birth control is always a good idea. Read more...
You Are not pregnan. Most probably an irregular period which are not unusual years presiding menopause due to unovulatoty cycles which are common at this stage of life. Read more...

Period 2 days late, had unprotected sex, two negative pregnancy tests. Will a blood test be accurate around this time?

Yes. A irone test should also be accurate,bit a blood test would certainly be an appropriate next step,prior to doing any further testing or giving anyeds. Read more...