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Yes, there is that oh so famous website that is incorrectly informing us POAS-ers of how the digital pregnancy test works. I'm tired of seeing it referred to incorrectly, here is the real deal.
The patent mentioned on that POAS site does actually refer to LH but not for the digital pregnancy tests. It's a patent so it's doing its job of covering the broad range of things that any digital test can do, measure HCG, i.e pregnancy tests or LH i.e ovulation tests. Clear Blue's patent not only explains and covers the use of the digital pregnancy tests but also their digital ovulation tests. The part where it refers to a strip picking up LH is clearly talking about the ovulation tests.
I have quite a bit of experience with patents. They are extremely complex and hard to read, to people who aren't' familiar with them it's like a foreign language.
Therefore, that POAS site's example of "secret of the digital" is completely incorrect. IT DOES NOT PICK UP LH! I see this referenced everywhere in forums and it drives me mad!
The REAL scoop:
Q: Why are there two or three lines on a digital even when you aren't pregnant?
A: The digital pregnancy test, tests for the the "free beta-subunit and beta-subunit core fragment" not just regular HCG. It is commonly referred in the chemistry field as BhCG. BhCG is something that is "free" in your system at all times. It is also one of the first hormones to become elevated during early pregnancy; even as early as 3 days after conception.
Yes, you did read that right. Hyperglycosylated hCG becomes elevated 3 days after the fertilization of the egg!
The digital test has nothing to do with LH or ovulation hormones at all!
The second faint line that is usually always there is produced from free bhCG. It really may mean nothing if you have two lines on your digital pregnancy test.
Now, I'm not saying that having 2 or 3 lines on a digital pregnancy test does not mean you're pregnant. I'm just saying that bhCG is always "free" in your system. So lines on a digital will happen, regardless of pregnancy or not. The important thing to look for is the increasing intensity of these lines.
A big mistake people make with the CB digital hpt tests is testing and getting a "pregnant" and then testing a few hours later, only to see a "not pregnant". It's best to only test once a day with the digital test because of it's lack of sensitivity.
A nifty little tidbit to add about the Clear Blue digital conception indicator tests; this is from the CB guide for the digital test with conception indication:
How the test works:
Unlike the traditional Clearable Pregnancy test, the new Clearable Digital Pregnancy Test with Conception Indicator contains two test strips – a low sensitivity strip and a high sensitivity strip.
If hCG is present in the urine it will bind to anti-αhCG antibodies attached to blue dye in the pad. As the hCG and anti-αhCG antibodies pass through the result line zone, they bind to anti-βhCG antibodies to form blue result lines. Both strips contain a ‘result’ line; the low sensitivity strip also contains a ‘control’ line. At low concentrations, hCG binds on the high sensitivity strip. At higher concentrations, hCG will alsobind to the low sensitivity strip. The concentration of hCG detected in the results lines of the two strips determines the result of the Conception Indicator: 1-2 weeks since conception; 2-3 weeks since conception; 3+ weeks since conception. If no hCG is present, the anti-αhCG antibodies attached to blue dye flow past the result zones on both strips, and no lines will be formed giving a ‘Not Pregnant’ result. If insufficient hCG is present, result lines may form but will be below the lowest thresholds set, and a ‘Not Pregnant’ result will be displayed.The lines produced on the strips cannot be read by eye. Instead, an optical system is used to measure the density of the lines. A red light shines onto these specific areas, and the light reflected is converted into an electrical signal.
Broken down into plain english:
2 strips, one high sensitivity - one low sensitivity
Each strip picks up and measures HCG
The low sensitivity strip detects of HCG and has a control line
The high sensitivity strip picks up low levels of bHCG
This part here: "The Test Monitors the control line on the low sensitivity strip and only when a valid control line has been detected will the result lines on both the strips be determined." I believe is where the discrepancy falls with CB digi tests. I believe that once the control line reaches a certain depth of color the optical light is triggered. Meaning that it's possible that the "result" lines may not have had enough time to darken to signal a "pregnant" when indeed the outcome was positive. This is represented by all the digital tests that are taken and "not pregnant" then put beside First Response when a clear pink test line is visible. Later on, the clearblue digital registers pregnant.
Last but not least pictures of "not pregnant" and "pregnant" results! There are pics showing very clearly showing 2 (or 3 in this case) lines when a no pregnant result was given. In some cases these people were pregnant, each pic will be marked with the outcome. Some will be consecutive pics, some will be alone, some are for the digital and some are for the digital with conception indicator, either way enjoy!
Low sensitivity strip on top and high sensitivity strip on bottom. This was a "not pregnant" result. Below is a day later with a "pregnant" result, strips are reversed.
Low sensitivity strip on top and high sensitivity strip on bottom (above)
Low sensitivity strip on right and high sensitivity strip on left (above)
Low sensitivity strip on bottom and high sensitivity strip on top (above)
Regular CB digital - All "not pregnant"Low sensitivity strip on top and high sensitivity strip on bottom (above)
high sensitivity strip on top and low sensitivity strip on bottom (above)
Low sensitivity strip on top and high sensitivity strip on bottom
Final word being; don't open the digital test (yeah right!) and if you do, two lines does not necessarily mean you are pregnant. It most certainly is NOT picking up LH either, see above.
If you have pictures to share; BFP or BFN please send them to me and I'll do my best to post them here!