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Hi all!
So last month you may or may not remember that I was getting faint positives that probably turned out to be evaporation lines because they were happening right at or just after that 10 minute mark.
I ended up getting my period RIGHT ON SCHEDULE.
It left me wondering if it was really evaporation lines or a pregnancy that didn't stick?
Anyhoo, tried again this month; I'm about 8DPO. A few weeks ago I bought some tests from They're sensitive to 20.
I did one test with serum about 2 days ago and got a very faint positive at about 5 minutes. Then did a urine test for fun and it also happened, but much later.
Did another one today and it took longer to show positive. So that confuses me but I suppose the lesson that I learned last time should apply. Wait till 14 dpo!! lol!!!
Anyway I wrote to the website asking at what point an evaporation line may show and got an interesting answer about how it happens. I'll paste below.
But even though I know I should wait, I had bought like 20 tests because they were only like $12
I won't be able to keep my hands off of them I'm sure.
Here's the info....
Hello Karen,

Thank you for your inquiry.

The evaporation line usually appears due to the application of too much
sample. The pregnancy tests measure very high sensitivity of hCG of 20mIU
with 99.9+% specificity. That means that you can find out if you are
pregnant very early, usually within 5-13 days of conception.

In clinical studies, our tests have not shown evaporation lines. These
results are based on lab controlled conditions. However in the real life
testing - in general these types of high sensitivity tests may be prone to
evaporation lines due to application of too much sample and reading the
results too late.

What happens when sample is applied, is that it flows through the entire
test device and is completely absorbed into the absorbant pad at the handle
area of the test strip (blue tape). The membrane area, where the test and
control lines show up, generally dries much faster than the absorbant pad
when there has been too much sample applied to the test. So if you apply
too much sample and read the results late (over 10 minutes) - capillary
action draws the sample backwards, from the absorbant pad onto the membrane
area. This will cause the 'evaporation line' because the sample now has
colored molecules dissolved in it, and once it dries off the membrane, it
will cause an irregular shaped color line. Because of this, it is very
important to follow the instructions exactly and only leave the test strip
in the sample for the amount of time specified. The test should be read at
5-10 minutes, not after that.

I hope that this information is helpful to you. If you have any further
questions or inquiries, please do not hesitate to contact us.

Best Regards,

Riley Stonehouse
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