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911Doctor
911Doctor, Doctor
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How often is a qualitative blood pregnancy test wrong

Resolved Question:

How often is a qualitative blood pregnancy test wrong?
Submitted: 6 years ago.
Category: Health
Expert:  911Doctor replied 6 years ago.

911Doctor :

Hello and welcome to JustAnswer,

911Doctor :

do you mean wrongly positive or wrongly negative?

Customer:

wrongly negative

Customer:

my girlfriend had one done 6 weeks after possible conception and it was negative

911Doctor :

then she is almost certainly not pregnant....

911Doctor :

how do you know she conceived?

911Doctor :

here are the numbers....

911Doctor :

http://www.babyhopes.com/articles/falsenegative.html

Customer:

i don't- we only had sex the one time, so she had the blood pregnancy test done 6 weeks after we had sex

911Doctor :

then she had the quantitative and not the qualitative test....

Customer:

oh ok

911Doctor :

their is a belief out their that the blood test is more accurate and in one sense that it right...

911Doctor :

it might pick up a pregnancy a few hours or a day prior to the urine test.... but the urine test is perfectly adequate....

Customer:

so there is no possibility that she is pregnant? the only reason i'm asking this is because she has had one period since we had sex, but she is currently 5 days late for her period

Customer:

and she also took a hpt this morning and it was negative

911Doctor :

then she is not pregnant....

911Doctor :

to be sure i would do one more test with the urine.... you can do it tomorrow if you like or the day after.....

911Doctor :

and the way to do the urine test is this....

911Doctor :

do the test on the first morning urine.... that way the hcg (pregnancy hormone) is the most concentrated and most likely to be found in the urine....

Customer:

ok

911Doctor :

the tests are extremely accurate...

Customer:

and if it is negative? why could her period be late?

911Doctor :

though i understand your concern.....

911Doctor :

her period could be late because she could have had a pregnancy and a miscarriage in the interim and her cycle may be off.... but if she is pregnant these tests will be postitive...

Customer:

ok thank you so much

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