The beta-hCG it is the name of human chronic boustrophedon, also known as the pregnancy hormone, as the body begins to secrete it at the time when the embryo implantation occurs in the endometrium. Hence its presence in blood and urine confirms the existence of a gestation very early: from 13 days, counting from the moment the ovarian puncture is performed for the extraction of eggs.
This test is considered to be positive when the values of the beta-hCG exceed 5 mUI/ml. If this figure is less than 4, absence of pregnancy is determined. The concentration of this hormone will be significantly higher in the case of a multiple pregnancy. Pregnancy is confirmed by a trans-vaginal ultrasound.
However, it is usual for the test to repeat after two or three days, as the concentration of this hormone in the blood doubles in just 48 hours. In fact, assisted reproduction procedures may result in a false positive as a result of one of the drugs used for the treatment of ovarian stimulation to which women are subjected to inducing ovulation, as contain this hormone, which makes it possible in the blood and its presence to be maintained for days.
If the repetition of the analysis determines that after 48 hours the same values are maintained or these have decreased, then it is that the pregnancy has not occurred.
It is also possible that the test result of the beta-hCG positive and that the woman has symptoms of pregnancy (nausea, drowsiness, abdominal swelling, etc.) but that there is finally no gestation. This happens in the case of the so-called an embryonic pregnancy, which occurs when the embryo has problems for its correct implantation in the uterus and is subsequently eliminated with the first period, in what is known as biochemical abortion.
They usually occur as a result of genetic or chromosomal embryo abnormalities The usual cause of this type of abortion is the existence of genetic or chromosomal abnormalities that occur at the time of fertilization or due to low quality of sperm or egg.