Pregnancy Testing At Home, How Accurate?
Probably it would be more rhetorically (grammatically?) accurate to say that a real pregnancy test is one where you can truly verify the pregnancy itself…like a transvaginal ultrasound...because that is the baby, not just a substance made by the placenta, which is what we are testing in the pee or the blood. But that requires a bit more patience as it takes awhile, at least a month or more into the pregnancy, for those ultrasound tests to be positive. Mostly though, the first test of pregnancy in your pee or your blood is a test for HCG or human chorionic gonadotropin. This is a substance made by placentas. HCG is secreted into the blood stream and then excreted out into the urine. And companies have developed extraordinarily accurate tests to determine the presence of HCG as early as possible in a pregnancy. And typically blood testing can pick up very minute levels and is very accurate. But now and then individuals (yes, rarely men too) can have circulating substance that shows a positive HCG test that is not HCG at all. It has been nick named “phantom” HCG. It is another antibody that is similar enough to the HCG molecule that it binds to the test agents and reads positive. Usually it only reads falsely positive in blood. These molecules tend to be large, and may not actually be spilled intact into the urine. So oddly, the negative urine test is more accurate in this case, and can reveal the true nature of the so called “phantom” HCG, or positive ‘pregnancy’ test when in fact there is no pregnancy. How common is this? I used to say rare, but some studies quote rates of 1-2% of the population may have these antibodies that may read this way on a test. So don’t just assume that blood tests are “better,” some interpretation is important for every test you ever take! And as we say to all the gals, gabbing with your gyno is the best way to solve these dilemmas!