1 doctor weighed in:

Can I trust a negative qualitative blood test 21 days after sex? I do not know when my period should come. Irregular periods.

1 doctor weighed in
Dr. Robert Sterling
Emergency Medicine

In brief: YesNoMaybePerhaps

Depends on when you ovulated and how long those sperm survived and made their way up the magic passage.
But overall it's hard to imagine a scenario where you couldn't trust the test if it was done correctly. Possible(like you had sex later in the last cycle), but not probable.General principle: When in doubt, repeat (in this case,sex if you want it, the test if you don't-or both). Short answer: Yes

In brief: YesNoMaybePerhaps

Depends on when you ovulated and how long those sperm survived and made their way up the magic passage.
But overall it's hard to imagine a scenario where you couldn't trust the test if it was done correctly. Possible(like you had sex later in the last cycle), but not probable.General principle: When in doubt, repeat (in this case,sex if you want it, the test if you don't-or both). Short answer: Yes
Dr. Robert Sterling
Dr. Robert Sterling
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