I learned this the hard way...here's why it happens:

If you place a wet OPK strip too close (especially if it's touching) to an hCG strip, some of the chemicals that detect LH in the OPK strip may leak sideways onto the hCG strip. Because you usually have at least some detectable LH in your urine, the leaked materials from the antibody strip on the OPK are now likely sitting in the indent line (the test line area) of your hCG test strip. Your hCG test strip will now appear positive when it comes into contact with LH, and may show a second line resulting from the presence of LH, not hCG (if you're actually pregnant, I'm not sure how much this matters).

Depending on how much LH you have in your system, this could make the second line very faint or very dark, and lead you to believe you're pregnant when you're not. I see this a lot on Amazon reviews of test strips, where someone will have a photo of an hCG strip literally touching a dripping OPK, with a strong pink line shooting across the hCG strip (usually fading the further it gets from the part of the OPK it's touching), with comments like "these pregnancy tests give false positives!" or "I think I had a miscarriage." This is a lot of undue hardship that can be easily avoided, so I wanted to share.

The top left photo is of 2 negative hCG tests I took moments before taking the hCG test on the right. The only difference is that for the tests pictured on the top right, I also took an OPK and touched the OPK and hCG strips while they were drying. Here are the results at 3 minutes:

As you can see, my LH isn't super high right now, but I'll post another one of these around when I'm ovulating. The more LH, the darker the "false positive" will be on the hCG strip touching the OPK. You don't really have a false positive hCG test...it's just basically an LH test now. This kind of user error could be avoided with more attention brought to this issue, & I wish it was more widely cautioned against.

Save yourself some heartache and faith in your test's accuracy and keep wet strips testing for different hormones away from each other until they dry!

Should i be worried?

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