How common is an evap line (false positive)

[userpin11]

Ok, driving myself crazy. In last year have had two very feint positive BFPs but then got AF within days both times. I had assumed they were chemical pregnancies, but didn't have blood tests or anything to confirm.

I've been clinging on to hope that the CPs mean I can conceive and the fertility clinic said the same. Thing is I am now worried they were just evap lines on the Boots tests and not PG at all.

Anyone know how common evap lines are or had a confirmed false positive? I don't want to assume all is ok when it could just be giving false hope.

Did the second line come up after the recommended time limit (is it 3 minutes usually?) or later? If within 3 minutes I don't think it would be an evap line.

As I understand it evap lines only come up once the test has "dried up" ie. at least an hour or so later, and that's why you shouldn't attempt to read the test result after the time it states.

However, an evap line would not have any colour. So if the line is the same colour as the test line, then I think it probably was a positive.

Sorry to hear you may have had chemical pregnancies, hope you get that BFP soon x

I've heard that tests that use blue dye are much more prone to evaporation lines. I had a couple do that with me. I have never had that problem with pink dye tests, even hours after taking them.