hCG (Human Chorionic Gonadotropin) is a peptide hormone -similar to LH in women- and, as its name suggests, it is usually produced in the chorion/trophoblast, that is, in placental and pre-placental cells.
This hormone is very important, as it is responsible for communicating to the woman's body that she is pregnant. Its fundamental effect is the maintenance of the corpus luteum.
But what is the corpus luteum? After ovulation, that is, when the oocyte leaves the follicle that was growing in the ovary, the follicle transforms into a corpus luteum (or corpus luteum). This mass is the main producer of the hormones estradiol and progesterone, especially the latter, which favors pregnancy. The corpus luteum is programmed to self-destruct in about 7 days unless hCG stimulation of an embryo stops the process. In this case, the menstruation does not come, and the pregnancy continues its course.
In this way, the hCG hormone is produced almost exclusively in the embryonic tissue, and that is why it has been used for many years as the best biochemical marker that a woman is pregnant.
However, it is possible that there is a high amount of hCG in the blood even though the patient is not pregnant. This occurs especially when there is a situation of abortion or abnormal pregnancies:
- Biochemical abortion
- beta hCG is not zero, since the embryo managed to implant itself in the uterus, although its development was interrupted after a few days, causing a drop in hCG levels. Although the test result may be positive, the pregnancy has been interrupted and, as it is an early abortion, there will be no sign that the woman is pregnant or, if anything, only a slight delay in her period.
- Ectopic pregnancy
- This happens when the embryo implants and grows outside the uterus, so the pregnancy cannot come to term. In this case, beta hCG tends to rise slowly or plateau.
- Decrease in beta after an abortion
- after suffering an abortion, the levels of hCG in the blood will clear up. However, the decrease is not immediate, so, on many occasions, this hormone is still detected days -and even weeks- after the abortion. This effect is greater the more advanced the pregnancy.
- Hydatidiform mole
- is a very special and very rare situation, in which the embryonic tissue degenerates into a type of tumor, which produces hCG (because it derives from the embryo). In reality, it is, therefore, an abnormal, degenerate pregnancy. This is a serious situation that should be treated by a specialist.
Apart from this, there are other situations in which the hCG does not come from pregnancy such as external injections, ovulation and in the case of a germ cell tumor.