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EPT?, Test strips? Dollar brand? What's the difference? Price (and advertising!) is the difference! Truth is, the digital test contains no special chemicals that detect pregnancy differently than a dollar brand or strip test, however - the digital test will interpret the 'lines' (or lack of) for you. All tests are FDA approved. If there were consistent, accurate claims of false negatives and positives - they would not be on the market as the FDA would have them pulled.
One thing to keep in mind when you believe a cheaper test gave you a wrong result: If you got a negative on the day your period was due, you were likely off in your calcualtion of when you ovulated. Some women will have an exceptionally long cycle - like 40 days before ovulation occurs. Lets say you are having a long cycle (unaware you have not ovulated yet, or ovulated much later than you thought) - you expect your period on CD 30... but nothing... you take a Dollar Test - BFN. Another three weeks go by, still no AF! What you didn't know was that you ovulated the day after your BFN (how mean and tricky your body can be to you!) ... you go get yourself a digital test: BFP!!!!!! You curse the Dollar Test as innacurate - but the truth is, you were not even pregnant.
Here is an explaination of how pregnancy tests work - in a nutshell: an antibody in the test will bind ONLY with hCG - a colouring indicator attached to the antibody will appear if the antibody binds to hCG.
This is from Answer.com:
Pregnancy tests rely on the presence of the hormone human chorionic gonadotropin (hCG), a glycoprotein that is secreted by the placenta shortly after fertilization. The placenta begins developing after the fertilized egg implants in a woman's uterus, which happens about six days after conception, so the earliest these tests can be used to detect pregnancy is about six days post-conception. Fertilization does not necessarily take place the same day as intercourse, so most women are advised to wait until they miss their period before trying a pregnancy test. hCG levels double about every two days in a pregnant woman, so the test is much more reliable two weeks after conception than one week later.
The tests work by binding the hCG hormone, from either blood or urine, to an antibody and an indicator. The antibody will only bind to hCG; other hormones will not give a positive test result. The usual indicator is a pigment molecule, present in a line across a home pregnancy urine test. Highly sensitive tests could use a fluorescent or radioactive molecule attached to the antibody, but these methods are unnecessary for an over-the-counter diagnostic test. The tests available over-the-counter versus obtained those at the doctor's office are the same. The primary difference is the decreased chance of user error by a trained technician. Blood tests are pretty much equally sensitive at any time. Urine tests tend to be most sensitive using urine from early morning, which tends to be more concentrated (would have the highest levels of hCG).
False Positives and Negatives
Most medications, including birth control pills and antibiotics, do not affect the results of pregnancy tests. Alcohol and illegal drugs do not affect the test results. The only drugs that can cause a false positive are those containing the pregnancy hormone hCG in them (usually used for treating infertility). Some tissues in a non-pregnant woman can produce hCG, but the levels are normally too low to be within the detectable range of the tests. Also, about half of all conceptions don't proceed to pregnancy, so there may be chemical 'positives' for a pregnancy that won't progress. For some urine tests, evaporation may form a line that could be interpreted as a 'positive'. This is why tests have a time limit during which you should examine the results. It's untrue that urine from a man will give a positive test result. (For more info on this, see 'When is a Positive Not a Positive')
Although the level of hCG rises over time for a pregnant women, the quantity of hCG for one woman is different from the amount produced in another. This means some women may not have enough hCG in their urine or blood right at six days post-conception to see a positive test result. All tests on the market should be sensitive enough to give a highly accurate result (~97-99%) by the time a woman misses her period.
Final note from me: Follow the basics - 1. use morning pee, 2. if BFN, patiently wait until AF is due to test again. 3. BFN on day period is due: you are either not pregnant or had a later ovulation. Wait a week and test again - if still BFN and no AF, a blood test might detect a very early pregnancy or a hormonal imbalance that's delaying your period.
***HOW OPKs WORK***
The principles of ovulation detection involve a chemical reaction that creates a color change on a test strip. This color change is proportional to the amount of luteinizing hormone (LH) in your urine. Determining when an LH surge has taken place is useful because you can expect an egg to be released about 12 to 24 hours afterward.
Reading an ovulation test simply calls for comparing the color change of your test to a control spot (where they have placed a known amount of LH) on the same strip. When your LH measurement is equal to or greater than the control amount, your surge has begun. The control spot is helpful for two reasons: one, its color change tells you that you ran the test properly; and two, it gives you a color comparison so you can tell when your test spot is positive.
The tests all come with detailed instructions and pictures of positive and negative results. In general, if your surge has not started, the control spot will be darker than your test area. If your LH surge has begun, however, the test area will turn dark, allowing you to see a dot or line there. Find more info in the OPK FAQ section.
***MY "WHEN IS THE OPK REALLY POSITIVE" RESEARCH***
So I have been obsessing about when is a positive OPK truly a positive OPK, as I have read mixed things about what to do when you have more than 24 hours of positives. Some things I read stated if multiple days of positives then add 12 - 48 hours to the last positive day to determine ovulation... other things I had read stated to stop testing with OPKs after your first positive, and add 12 - 48 hours to that. So after posting on several fertility related websites, and calling three OPK manufacturers... the results are in.... drumroll please.... the first OPK that is a TRUE positive (where there is no question about it being as dark as or darker than the control strip) is the one to believe.... BUT if you continue to get positives then continue to BD, just in case your ovulation is delayed. LH can indeed hang around even if you have ovulated, and in levels as high as surge levels! ClearBlue was the only manufacturer to acknowledge that a surge does not guarantee ovulation, and even after one positive OPK, it is possible to have a second surge later in the month where ovulation actually happens. The Answer OPK people practically guaranteed that not only did I ovulate on the first positive OPK, but that I was now certainly pregnant thanks to Answer OPKs! Ummm, sorry hubby, you get no credit ;) (lol - I never even used OPKs this month... I was 'posing' as an Answer OPK user... I used them back in April, does that count?) So the moral is - BD anyways, at least until the week before you expect AF.
