Changes in hCG in ectopic pregnancy and their diagnostic value

, medical expert
Last reviewed: 19.10.2021

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During pregnancy, multiple changes occur in the woman's body. Some of them are visible to the naked eye, while others are so hidden that they can be identified only through ultrasound or laboratory diagnosis. For example, changes in the hormonal background, and they are especially noticeable, before the appearance of external symptoms that indicate violations, can be determined only by laboratory methods. So the level of hCG with ectopic pregnancy will be significantly lower than normal, and the cause of increased levels of this hormone can become gestational diabetes or chromosome pathologies of the fetus.

It is the laboratory way doctors sometimes accidentally reveal serious pathologies of pregnancy already in the early stages. And although it is difficult to judge the specific diseases on the basis of a single analysis on HCG or AFP, the change in the level of hormones allows you to suspect the disease in time and take the necessary steps to treat it, and if necessary, interrupt the pathological pregnancy.

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To whom and when is the HCG analysis scheduled?

A general blood test and urinalysis, which are mandatory for women in the diagnosis of pregnancy, including ectopic, and registration, can tell a lot about the health of a future mother. But they do not give enough information about the development of the fetus at different periods of pregnancy and its localization. And after all, bearing a child is a rather complicated and lengthy process, each stage of which is accompanied by certain changes in laboratory indicators, which can only be traced through special tests and tests.

One such special analysis in pregnancy is the study of human chorionic gonadotropin (hCG) levels. What is hCG? This is a specific hormone, which is practically absent in a healthy person outside the period of pregnancy. In men, the detection of chorionic gonadotropin in the blood is possible only with the development of oncological diseases of the reproductive system (teratoma / seminoma of the testicle). Such neoplasms are most often detected in boys and young men. In this case, the analysis on HCG helps to clarify the diagnosis.

An increase in the level of chorionic gonadotropin in a woman with a high probability indicates the onset of pregnancy. The fact is that for the production of this unusual hormone is responsible for the embryo, or rather its shell, which provides fetal nutrition and is called chorion. Therefore, the hormone is called chorionic. Later on, when placenta is formed (approximately 3-4 months after pregnancy), it also begins to produce hCG, but in a smaller amount.

Chorion is the outer envelope of the fetus, which supports the function of the temporary endocrine gland (yellow body) from the moment of conception and to the formation of the placenta. The vitality of the yellow body, producing estrogens and progesterone, necessary for maintaining the pregnancy, is preserved precisely through the development of the chorionic gonadotropin. That is, these processes are interrelated and aimed at preparing the body of a woman for bearing a child. It is not surprising that gonadotropin begins to be produced by chorion almost from the moment of conception of the child, as soon as the father's sperm merges with the mother's egg.

The level of the hormone of pregnancy rises markedly from day to day until 8-12 weeks of pregnancy, after which it gradually declines, which is due to the preparation of the organism for childbirth. After all, when the placenta forms in the second trimester of pregnancy, all the main organs and systems of the child are already formed and begin to function. This is already a full-fledged little man, who is gradually preparing for independent existence outside the mother's womb.

What is so important for hCG during pregnancy? The fact that it is thanks to him supports the necessary level of all other hormones in the female body, including estrogens and progesterone, which is very important for the normal course of pregnancy. It is clear that the deviation of the level of hCG from normal indices will indicate certain violations.

What are the indications for the analysis of hCG:

  • He is prescribed to women who have a delay or lack of menstruation without any other symptoms of pregnancy. An increase in the level of chorionic gonadotropin will be evidence of the conception that has occurred, otherwise it involves some violations in the reproductive system.
  • With the help of the analysis, you can identify pregnancy at a very early age, because the increase in the level of hCG in the urine is noted already on the 6-8 day after conception (this is one of the fastest methods of determining pregnancy), and in venous blood, even for 2-3 days.
  • The study is prescribed for suspected multiplane pregnancy, when two or more embryos grow in the womb and mature at the same time.
  • The analysis is especially relevant if the doctor has reason to presume an ectopic or frozen pregnancy that requires immediate surgical intervention and termination of pregnancy (hCG in ectopic pregnancy or stopping the development of the fetus in the womb will have deviations from the norm).
  • after a spontaneous abortion or unprofessional abortion, there are situations when the tissues of the embryonic and placental tissues are not completely removed from the body, which poses a danger to the health of the woman. The presence of chorionic and placenta residues will be indicated by the high level of hCG, the products of which they are engaged, in norm in the absence of pregnancy, hCG should not exceed 5 IU per ml of blood.

It must be said that this analysis is prescribed for pregnant women today and without any indication. This delicate period in a woman's life has several critical phases: 8, 12-14, 16-18 weeks of pregnancy. It is at this time with greater probability of pregnancy fading or other pathologies. In connection with this, screening studies are carried out specifically for these critical phases, which enables timely diagnosis of complications of pregnancy.

The growth of hCG values tells how the fetus grows and develops. Therefore, the analysis on hCG along with the study of blood on alpha-fetoprotein and estriol is included in the complex of prenatal diagnosis of pathologies of fetal development.

At various pathologies of pregnancy the analysis on hCG can be spent in dynamics, i.e. With an interval of 2 days. The fact is that during normal pregnancy during this period there is a doubling of the chorionic gonadotropin in the blood. With ectopic pregnancy and even more so when fetal fading, the increase in hCG is much less intense.

Preparation and technique of analysis

To determine the level of chorionic gonadotropin in pregnancy, various methods of laboratory diagnosis are used. The simplest variant of the assay are test strips, the mechanism of action of which is based precisely on the increase in the level of hCG after conception.

The pregnancy test can be purchased at any pharmacy and even in grocery supermarkets. It is a light strip with a reagent applied to it, which changes color upon contact with the urine, resulting in a second stripe that indicates pregnancy.

The matter is that after 6-8 days after conception in urine there is already sufficient level of gonadotropin for diagnosing pregnancy. Another thing is that the sensitivity of most tests allows you to detect pregnancy only after 2 or more weeks. The most accurate are the inkjet and digital tests, which should not be lowered into a container with urine or dripping urine on them, but delivered under a fresh stream.

10 seconds of contact of the test strip with urine is sufficient for the reaction to begin, and its result can be seen after 1-10 minutes, depending on the level of hCG. But if the usual tests for hormone concentration and pregnancy time can be judged mainly on the intensity of the color of the manifested stripe, the electronic version of the test will provide information in a digital version.

Such an analysis on hCG is quite suitable for determining pregnancy, but it can say little about its timing and the nature of the course. Those. The usual tests for hCG with ectopic pregnancy will be of little informative. They will show the presence of pregnancy in any case, but the level of gonadotropin and the dynamics of its growth can only be guessed. Suspicious may seem insufficiently intense color of the second strip or its absence during repeated inspections.

The digital test in this regard is more interesting, because it allows you to evaluate the concentration of the hormone, and in the second analysis even assess how much the hCG level has increased over a certain period of time. Such changes give a greater percentage of true results in the first 2 months of pregnancy, after which such incidents as a negative result of a pregnancy test are possible.

In a similar way, urine is analyzed for chorionic gonadotropin in the laboratory. A pregnant woman in this case will need to pass on a fresh morning urine analysis. Why the morning? Because the concentration of the gonadotropin affects the volume of the liquid being drunk. The more water a woman drinks, the lower the concentration of the pregnancy hormone, which will distort the true results. The day before taking the test, it is also not recommended to drink plenty of fluids, especially before going to bed.

With ectopic pregnancy and other complications, the most appropriate is to conduct a blood test for hCG. In the blood gonadotropin is detected faster than in the urine, and the results of the blood test are considered the most accurate. Blood is taken from the vein, after which a liquid part is separated with the help of a centrifuge and reagents are added. The analyzer converts the quantitative results into digital, which is used to diagnose the course of pregnancy.

Any analysis is of diagnostic value, if its results are reliable, therefore, some preparation is often required before the analysis. Ideally, blood, like urine, must be taken in the morning before breakfast, some time after awakening. But even if the blood will have to be taken at another time, to improve the accuracy of research, it is recommended to refrain from eating and limit the use of water and 5-7 hours before taking blood for analysis.

Ectopic pregnancy

Almost every woman dreams at one perfect moment to become a happy mother of her own baby. But for this she has to conceive and endure a child. Fertilization of the egg occurs after its release into the fallopian tube, but this is not enough for the normal development of pregnancy. In the future, the duet from which the human embryo (embryo) is formed, must follow the fallopian tube directly to the uterus, where it is fixed to a permanent place of residence 2-3 weeks after the occurred conception.

But sometimes it happens that the egg in the allotted time does not have time to infiltrate the uterus and it has to "settle" elsewhere. Most often, the site of its localization is the uterine tube itself, less often the fetal egg is fixed near the ovary, in the abdominal cavity or cervix of the uterus. In any case, if the embryo develops outside the uterus, one speaks of a pathology called "ectopic pregnancy".

This situation is considered unsuitable for the normal development of the child, especially if the fetus is entrenched inside the uterine tube. The dimensions of the lumen of the fallopian tube are not calculated to increase the fertilized egg, which occurs as the fetus grows and develops, so the fetus lags behind in development and soon dies. To keep such a pregnancy just does not make sense.

Moreover, ectopic pregnancy is a threat to the life of a pregnant woman. A small lumen of the fallopian tube and insufficient elasticity of its walls are a risk factor for organ rupture as the fetus grows. This is an extremely dangerous situation, in which there are severe pains and profuse internal bleeding. If the patient does not help in time, the woman faces death. And even if doctors manage to save her life, it will not be possible to restore the damaged uterine tube, so the possibility of becoming pregnant will be extremely low. After all, even after a timely intervention, the chances of pregnancy are reduced by half.

In the first months after conception, it is almost impossible to distinguish ectopic pregnancy from normal without special studies. A woman can even develop a toxicosis in the early stages, swell the mammary glands, stop menstruating or turn into a monthly meager daub.

Regardless of the site of embryo localization, a protective shell (chorion) surrounds it, which produces chorionic gonadotropin, which means that the level of hCG in ectopic pregnancy will increase. What, then, can analysis help in such a situation? And the fact that hCG in uterine and ectopic pregnancy are significantly different.

The level of hCG in ectopic pregnancy

Ectopic pregnancy is a situation in which the fetus can not develop normally. While it is small and can be safely placed in the lumen of the uterine tube, development can proceed normally, as evidenced by the regularly increasing level of chorionic gonadotropin. But gradually the dynamics of hCG growth in ectopic pregnancy changes.

To better understand the difference between the increase in hCG in uterine and ectopic pregnancy, you need to know the level of chorionic gonadotropin in the absence of pregnancy. It is believed that the concentration of this specific hormone changes every 1.5-2 days, during which the indices increase almost twice. That is, after taking measurements of hCG at intervals even in some couple of days, it is already possible to draw definite conclusions about the course of pregnancy.

It makes no sense to describe daily changes in hCG during pregnancy, it is enough to consider its norm for weeks with normal fetal development, and then compare the rates of hCG with the rates that are observed with ectopic pregnancy.

If a woman is not pregnant, gonadotropin in her blood may not be detected or contained in amounts not exceeding 5 IU / mL. This is the so-called reference point, called referential. Further increase in hCG will indicate already on pregnancy in women or oncology in men. But since the chorionic gonadotropin begins to be released already from the moment of conception of the fetus, in the first week of pregnancy its indices can rise up to 20-35 IU / ml.

During 1-2 weeks of pregnancy, when the fetus is still on the way to the uterus, the content of hCG in the woman's blood ranges from about 20 to 350 IU / ml. We emphasize the word "approximately", because different laboratories determine the concentration of gonadotropin during pregnancy by various methods that can give different results. Therefore, in each institution of this nature, developed their own tables that determine the rates of hCG in normal and pathological pregnancies.

Here is an example of one of such tables, where the first column will reflect the gestation period by weeks, and the second upper and lower limit of the hCG in IU per ml of blood.























If the results of hand-written tests are within the scope of the table above, this can not be considered an excuse for panic. The table is strictly for informational purposes and on its basis we can see how before the 7-11 weeks of pregnancy, hCG rates are skyrocketing, and then gradually begin to decline.

We examined the dynamics of chorionic gonadotropin in the normal course of pregnancy and the correct location of the fetus, and what is the hCG in ectopic pregnancy? In general, the picture is identical: first, there is an increase in hCG values, and then its fall. But here the increase in the level of hCG in this case is significantly lower than with a normally developing pregnancy.

So, during the first two weeks of pregnancy, the difference in the growth of the chorionic gonadotropin may not be observed. But already at the 3-4 week indicators may be less than 2 and more times than it is necessary for this period. The maximum level of hCG in ectopic pregnancy usually does not exceed 75,000 IU / ml, while in normal pregnancy in the same period the indicators will reach 291000 IU / ml.

As you can see, the difference is palpable. A low level of chorionic gonadotropin is an indicator that the fetus is lagging behind in development, and with its localization in the fallopian tube this is inevitable. And no matter how the fruit was conceived. When in vitro fertilization, when a fertilized egg is inserted directly into the woman's uterus, there are also situations when the embryo changes its location, slipping into the uterine tube or abdominal cavity, where it is later fixed and grows. HCG in ectopic pregnancy after IVF has the same dynamics as in natural conception, which did not result in the transfer of the egg to the uterus.

If the ectopic pregnancy is not detected in the first weeks after conception, the slow growth of hCG is observed up to about 7-8 weeks, and then falls. At this time, the fading of the fetus is most often noted, when it ceases its development and perishes, which, if not properly located, is most likely. But such a break can happen before.

The level of hCG in the dead pregnancy never reaches a high level and after the death of the embryo begins to decline rapidly. But to normal for not pregnant level he can come nearer only after a spontaneous abortion or abortion, and that long in that case if in an organism of mother there were no particles of fabrics of an embryo or a placenta.

With ectopic pregnancy and embryo delay in the fallopian tube, there is no independent rejection of the embryo, even if the fetus is frozen. In this case, with persisting pathological pregnancy, the level of hCG will be extremely low and without surgical intervention it can not be dispensed with.

Changes in hCG in ectopic pregnancy, different from the norm, allow one to suspect a pathology, but this is not enough to make an accurate diagnosis. Decrease in the indices of this hormone is also observed when there is a threat of miscarriage, caused by a delay in the development of the embryo, or placental insufficiency. Even such symptoms as pains in the lower abdomen and smearing brown or red discharge are not specific, and it is impossible to diagnose them. Therefore, to confirm ectopic pregnancy, ultrasound results are also important, which will show the absence of a fetus in the uterus in the presence of other symptoms of pregnancy.

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