Diagnostic tests to assess the course of pregnancy

Determination of basal temperature in the first 12 weeks of pregnancy. In case of favorable pregnancy, basal temperature is increased to 37.2-37.4°C. Temperature below 37°C with fluctuations indicates unfavorable pregnancy. The capabilities of this test are very limited, since in case of non-developing pregnancy, in case of anembryony, the temperature remains elevated as long as the trophoblast lives.

Cytological examination of vaginal discharge is currently rarely taken into account, since among women with miscarriage there are many infected with cervicitis, vaginosis, in which the study is not informative, in the absence of infection this test can be used. Up to 12 weeks of pregnancy, the cytological picture of a smear of vaginal contents corresponds to the luteal phase of the cycle and the karyopycnostic index (KPI) does not exceed 10%, at 13-16 weeks - 3-9%. Up to 39 weeks, the KPI level remains within 5%. When signs of a threat of interruption appear, erythrocytes appear in smears simultaneously with an increase in KPI, which indicates an increase in the level of estrogens, an imbalance in progesterone-estrogen relations and the appearance of micro-detachments of the chorion or placenta.

Dynamic determination of the level of chorionic gonadotropin has great prognostic value for assessing the course of pregnancy in the first trimester. It is determined in urine or blood in the 3rd week of pregnancy. Its content in urine increases from 2500-5000 U at 5 weeks to 80,000 U at 7-9 weeks, decreases to 10,000-20,000 U at 12-13 weeks and remains at this level until 34-35 weeks, then increases slightly, but the significance of this increase is unclear.

Since chorionic gonadotropin is produced by the trophoblast, its dysfunction, detachment, dystrophic, generative changes lead to a decrease in the excretion level of chorionic gonadotropin. To assess the course of pregnancy, not only the value of chorionic gonadotropin is important, but also the ratio of the peak value of chorionic gonadotropin to the gestational age. Too early appearance of the peak of chorionic gonadotropin at 5-6 weeks, as well as late appearance at 10-12 weeks and, to an even greater extent, the absence of the peak of chorionic gonadotropin indicate a dysfunction of the trophoblast, and therefore the corpus luteum of pregnancy, the function of which is supported and stimulated by chorionic gonadotropin.

It should be noted that early appearance of chorionic gonadotropin and its high level can occur in multiple pregnancies. In non-developing pregnancies, chorionic gonadotropin sometimes remains at a high level, despite the death of the embryo. This is due to the fact that the remaining part of the trophoblast produces chorionic gonadotropin, despite the death of the embryo. Termination of pregnancy in the first trimester in most cases is the result of the failure of the trophoblast as an endocrine gland.

To assess the course of pregnancy, such a test for assessing the function of the trophoblast as determining placental lactogen in blood plasma can be used. However, it is more often presented in scientific studies to confirm or deny the formation of placental insufficiency than in clinical practice. Placental lactogen is determined from the 5th week of pregnancy, and its level constantly increases until the end of pregnancy. With dynamic monitoring of the level of placental lactogen, the absence of an increase or a decrease in its production is an unfavorable sign.

In the first trimester of pregnancy, determination of estradiol and estriol levels has great prognostic and diagnostic value.

A decrease in the level of estradiol in the first trimester, estriol in the second and third trimesters indicates the development of placental insufficiency. However, in recent years this test has been given less importance and is mainly used to assess placental insufficiency by ultrasound and Doppler ultrasound of the fetoplacental and uteroplacental blood flow, since it is believed that a decrease in estriol may be due to a decrease in aromatization processes in the placenta, and not to fetal distress.

A decrease in estriol production is noted when taking glucocorticoids.

In women with hyperandrogenism, the determination of the 17KS content in daily urine plays an important role in monitoring the course of pregnancy and assessing the effectiveness of glucocorticoid therapy. Each laboratory has its own standards for the level of 17KS, with which the obtained data should be compared. It is necessary to remind patients of the rules for collecting daily urine, the need for a diet without red-orange coloring products for 3 days before collecting urine. In uncomplicated pregnancy, there are no significant fluctuations in the excretion of 17KS depending on the gestational age. Normally, fluctuations are from 20.0 to 42.0 nmol / l (6-12 mg / day). Simultaneously with the study of 17KS, it is advisable to determine the content of dehydroepiandrosterone. Normally, the level of DHEA is 10% of the excretion of 17KS. During pregnancy, significant fluctuations in the level of 17KS and DHEA do not occur. An increase in the content of 17KS and DHEA in urine or 17OP and DHEA-S in blood indicates hyperandrogenism and the need for treatment with glucocorticoids. In the absence of adequate therapy, the development of pregnancy is most often disrupted by the type of non-developing pregnancy; in the II and III trimesters, intrauterine fetal death is possible.

An extremely important aspect of working with patients with habitual miscarriage is prenatal diagnostics. In the first trimester, at 9 weeks, a chorionic biopsy can be performed to determine the karyotype of the fetus to exclude chromosomal pathology. In the second trimester, to exclude Down's syndrome (if the study was not performed in the first trimester), it is recommended that all pregnant women with a history of habitual pregnancy loss undergo a study of the levels of human chorionic gonadotropin, estradiol, and alpha-fetoprotein in the mother's blood. Studies are performed at 17-18 weeks. An increase in human chorionic gonadotropin above the standard parameters for this period, a decrease in estradiol and alpha-fetoprotein are suspicious of Down's syndrome in the fetus. With these indicators, all women, and after 35 years, regardless of the parameters obtained, must undergo amniocentesis with an assessment of the karyotype of the fetus. In addition to this analysis, in all cases with hyperandrogenism and a burdened anamnesis with suspected adrenogenital syndrome (if the spouses have HLAB14, B35-B18 in the system and are possible carriers of the adrenogenital syndrome gene in the family), we conduct a study of the levels of 17-hydroxyprogesterone in the blood. If this parameter in the blood increases, amniocentesis and determination of the level of 17OP in the amniotic fluid are performed. Increased levels of 17OP in the amniotic fluid indicate the presence of adrenogenital syndrome in the fetus.

The most informative test for assessing the course of pregnancy, the condition of the embryo, fetus, and placenta is an ultrasound scan. In most cases, ultrasound allows determining pregnancy from the 3rd week and indicating the location of the pregnancy in the uterus or outside it. At this time, the fertilized egg is a round formation free of echostructures, located in the upper or middle third of the uterine cavity. At the 4th week of pregnancy, it is possible to identify the contours of the embryo. According to ultrasound data, the uterus begins to enlarge from the 5th week, and the placenta begins to form from the 6th-7th week. Valuable information about the nature of the pregnancy can be obtained by measuring the uterus, fertilized egg, and embryo. Simultaneous determination of the size of the uterus and fertilized egg allows identifying some pathological conditions. With normal sizes of the fertilized egg, a decrease in the size of the uterus is noted with its hypoplasia. An increase in the size of the uterus is observed with uterine fibroids. Multiple pregnancy is determined in the early stages of pregnancy. Based on the size and condition of the yolk sac, one can judge how the pregnancy is progressing in its early stages. Echography is one of the most important methods for diagnosing a non-developing pregnancy. It reveals blurred contours and a decrease in the size of the ovum, the embryo is not visualized, and there is no cardiac activity or motor activity.

However, one cannot rely on a single study, especially in the early stages of pregnancy, dynamic monitoring is necessary. If repeated studies confirm these data, then the diagnosis of non-developing pregnancy is reliable.

At a later stage, signs of a threat of termination may be noted due to the condition of the myometrium.

Often, in the presence of bloody discharge, areas of placental abruption are detected, and echo-negative spaces appear between the uterine wall and the placenta, indicating an accumulation of blood.

Uterine malformations are better detected during pregnancy than outside of it. Isthmic-cervical insufficiency is diagnosed if there is already a change in the cervix and prolapse of the fetal bladder.

An extremely important aspect of ultrasound is the detection of fetal malformations. Identification of the features of the placenta, localization, size, presence or absence of placentitis, structural anomalies, presence or absence of placental edema, infarctions, degree of maturity of the placenta, etc.

The amount of amniotic fluid: polyhydramnios may occur with fetal malformations and infection; oligohydramnios is a sign of placental insufficiency. An extremely important aspect is the presence of placental abruption, retrochorial hematomas, and the phenomenon of placental "migration".

An extremely important method for assessing the condition of the fetus is the Doppler evaluation of the uteroplacental and fetoplacental blood flow, its compliance with the gestational age. Studies are conducted from 20-24 weeks of pregnancy with an interval of 2-4 weeks depending on the condition of the fetus. Registration of the spectra of the curves of blood flow velocities of the left and right uterine arteries, the umbilical artery and the middle cerebral artery of the fetus is carried out. The assessment of the curves of blood flow velocities is carried out by analyzing the maximum systolic (MSBV) and end diastolic blood flow velocities (EDBV) with the calculation of angle-independent indicators: systolic-diastolic ratio, resistance index (RI) according to the formula:

IR = MSK - KDSK / MSK

, where the index (IR) is an informative indicator characterizing the peripheral resistance of the vascular system under study.

Cardiotocography - monitoring of the condition of the fetus is carried out starting from the 34th week of pregnancy at intervals of 1-2 weeks (as indicated).

Analysis of uterine contractility can be performed on a cardiac monitor, since CTG recording can be performed simultaneously with recording of uterine contractility, and can also be performed using hysterography and tonusometry.

Hysterograms are recorded on a single- or three-channel dynamometer. For quantitative assessment of hysterograms, the device has a calibration device, the signal of which corresponds to 15 g/cm ². Registration is carried out with the pregnant woman lying on her back. The device sensor is fixed to the anterior abdominal wall in the area of the uterine body using a belt. The duration of an individual study is 15-20 minutes. Hysterograms are processed using qualitative and quantitative analysis methods, taking into account the duration, frequency, and amplitude of an individual contraction.

Tonometry - a tonometer developed by Khasin A.Z. et al. (1977) is used. The device is made in the form of two cylinders of different diameters. The larger cylinder is hollow. The second cylinder is smaller, the reference mass is located inside the first and can move relative to it. The degree of movement of the movable cylinder depends on the compliance of the support on which it is installed and the area of the end part of the inner cylinder. The depth of immersion of the movable cylinder into the underlying base is noted on the measuring scale of the tonometer and is expressed in conventional units. The measurement is made with the woman lying on her back. The device is installed along the midline of the abdomen on the anterior abdominal wall in the projection zone of the uterus. The tone of the uterus is measured in conventional units. If the tonometer readings are up to 7.5 conventional units, the tone of the uterus is considered normal, and more than 7.5 conventional units is regarded as an increase in the basal tone of the uterus.

Of course, an experienced clinician can tell whether the uterus is in tone or not by palpating it, but when determining the effectiveness of different methods of therapy, when evaluating different observation groups, what is needed is not clinical conclusions, but an accurate digital reflection of the process, so this method of evaluation is very convenient, especially in the conditions of antenatal clinics.

Other research methods necessary for assessing the course of pregnancy: assessment of the hemostasiogram, virological, bacteriological research, assessment of the immune status are carried out in the same way as in the study before pregnancy.

24-hour blood pressure monitoring. Hemodynamic disorders contribute to complications during pregnancy. Arterial hypertension is registered in 5-10% of pregnant women. Arterial hypotension occurs in 4.4% to 32.7% of pregnant women. Excessive decrease in blood pressure leads to hypoperfusion of the myocardium, brain, skeletal muscles, which often contributes to complications such as dizziness, fainting, weakness, fatigue, etc. Long-term hypertension, as well as hypotension, adversely affects the course of pregnancy. The method of 24-hour blood pressure monitoring (ABPM) in pregnant women allows more accurate determination of hemodynamic parameters than just a single determination of blood pressure.

The ABPM device is a portable sensor weighing about 390 g (including batteries), which is attached to the patient's belt and connected to the arm cuff. Before starting the measurement, the device must be programmed using a computer program (i.e. enter the required intervals for measuring blood pressure, sleep time). The standard ABPM method involves measuring blood pressure for 24 hours at 15-minute intervals during the day and 30-minute intervals at night. Patients fill out a monitoring diary in which they note the time and duration of periods of physical and mental activity and rest, time of going to bed and waking up, moments of eating and taking medications, the onset and cessation of various changes in well-being. These data are necessary for subsequent interpretation of the ABPM data by the doctor. After the 24-hour measurement cycle is completed, the data are transferred via an interface cable to a personal computer for subsequent analysis, output of the obtained results to the monitor display or to a printer and their storage in a database.

When conducting ABPM, the following quantitative indicators are analyzed:

1. Arithmetic mean values of systolic, diastolic, mean arterial pressure and pulse rate (mmHg, beats per minute).
2. Maximum and minimum values of blood pressure at different times of the day (mmHg).
3. Temporal hypertensive index is the percentage of monitoring time during which the blood pressure level was above the specified parameters (%).
4. Temporary hypotonic index - percentage of monitoring time during which the blood pressure level was below the specified parameters (%). Normally, temporary indices should not exceed 25%.
5. The daily index (the ratio of average daily values to average night values) or the degree of nighttime decrease in blood pressure and pulse rate is the difference between average daily and average night values, expressed in absolute figures (or as a percentage of average daily values). A normal circadian rhythm of blood pressure and pulse rate is characterized by at least a 10% decrease during sleep and a daily index of 1.1. A decrease in this indicator is usually characteristic of chronic renal failure, hypertension of renal and endocrine genesis, hypertension during pregnancy and preeclampsia. Inversion of the daily index (its negative value) is detected in the most severe clinical variants of the pathology.

The hypotension area index is the area limited below by the graph of pressure versus time and above by the line of threshold values of arterial pressure.

Variability of SBP, DBP and heart rate, most often assessed by the standard deviation from the mean. These indicators characterize the degree of damage to target organs in hemodynamic disorders.

Daily monitoring of arterial pressure in the obstetric clinic has high diagnostic and prognostic significance. Based on the results of the applied arterial pressure monitoring in the miscarriage clinic, the following conclusion can be made:

1. Daily monitoring of blood pressure in pregnant women allows for a much more informative identification and assessment of the severity of arterial hypotension and hypertension than with episodic measurements.
2. Almost half of patients with miscarriage (45%) experience hypotension not only in the early stages, but also throughout the entire pregnancy.
3. Despite the fact that the problem of hypotension as a pathological condition has been discussed in the world literature recently and there is no clear final opinion regarding its nature, the adverse effect of hypotension on the course of pregnancy and the condition of the fetus is obvious. We have identified a close relationship between hypotension and the presence of placental insufficiency in patients with a history of miscarriage, and in the presence of severe hypotension, more severe fetal suffering is noted, confirmed by objective methods of functional diagnostics.
4. All pregnant women experience a “white coat effect” that masks the true level of blood pressure, leading to an erroneous diagnosis of hypertension and to unjustified hypotensive therapy, which further worsens the condition of the patient and fetus.
5. Repeated daily monitoring of blood pressure during pregnancy will allow timely detection of not only the initial signs of changes in blood pressure in patients, but also improve the quality of diagnostics of placental insufficiency and intrauterine fetal distress.
6. Further study of the course of pregnancy, the condition of the patient and the fetus using this method will allow a deeper approach to the issues of pathogenesis of arterial hypertension, hypotension during pregnancy, placental insufficiency. Daily monitoring of arterial pressure during pregnancy has not only diagnostic and prognostic, but also therapeutic significance, since it allows determining individual treatment tactics, its effectiveness, thereby reducing the frequency of pregnancy complications and improving the outcome of labor for the fetus.

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