Where The Results of Pregnancy Tests Come From
The fallopian tubes are a pair of thin tubes connecting the ovaries of women and female mammals to the uterus. In reproduction, an ovary bursts, releasing an egg, which then travels along the fallopian tube and into the uterus. If the egg is fertilized while in the fallopian tube, it usually implants itself in the endometrial lining of the uterus. It's at this point that pregnancy tests will yield a positive result, as the fertilized egg is the very first stage of embryonic life. However, if the egg is not fertilized, it dies and decays in the uterus and is later flushed from the body during the menstrual flow. An unfertilized egg gives a negative result on pregnancy tests.
On occasion, a fertilized egg will implant itself in the lining of the fallopian tube, leading to what is called a "tubal pregnancy" or "ectopic pregnancy". These pregnancies usually terminate quickly as there isn't enough room in the fallopian tube to hold a growing embryo. In some cases it's necessary for a doctor to remove or attempt to re-situate the egg, moving it into the uterus, as ectopic pregnancies can be very painful. An ectopic pregnancy does return a positive result on pregnancy tests. However, pregnancy tests post-surgery may be a bit muddled as the hormonic balance is upset by surgical intervention.
The Importance of the Fallopian Tubes
Fallopian tubes are an absolutely essential piece of the reproductive puzzle. They serve a vital position, directing traffic within the female reproductive system, giving the egg time and a place to be fertilized before reaching the uterus. If not for the fallopian tubes, pregnancy tests would be much more difficult, as the egg's arrival in the uterus triggers a series of complicated chemical interactions. Pregnancy tests trying to look for traces of hCG (human Chorionic Gonadotropin) might not be able to detect it beneath the swell of hormones and cellular growth, if the egg were not already given time for fertilisation.
Some women, when they've had a few children, decide to go through a tubal ligation, in which the fallopian tubes are clinched or sealed shut in a surgical procedure. These women have taken all the pregnancy tests they ever want to take, and they're happy with the children they've got. A tubal ligation stops the egg from entering the fallopian tube, because it encounters a wall of scar tissue or a surgical steel clamp. While tubal ligations are not easily reversible, there have been cases in which women who believed they were no longer able to have children received positive results on pregnancy tests. Pregnancy tests can surprise anyone!
