Gary Carpenter, BioSure (UK) Limited Workon 10th April 2018
Thanks for getting in touch.
You should only read the result up to one hour after the test is completed. It is for exactly this reason that we say this. The test line can become discoloured by blood cells from your sample. So if it was negative at 20 minutes, that is your result.
If you could take a photo of the test that and email it to me, I would appreciate it, for our records. My email is firstname.lastname@example.org.
BioSure (UK) Limited