Diagnosis of pregnancy and pregnancy disorders

The importance of radiation methods in the diagnosis of pregnancy and its disorders is very great. It is enough to list the main tasks of radiation studies.

This is, firstly, confirmation of the fact of pregnancy, establishment of the location of the fetus (in the uterus or abdominal cavity), determination of the number of fetuses, clarification of the age and sex of the fetus and the correctness of its development, recognition of fetal anomalies and its death. Secondly, assessment of the position, size and condition of the placenta and amnion. Thirdly, measurement of the pelvis and assessment of the condition of the birth canal (in particular, exclusion of obstacles to the birth act, such as pelvic deformations, ovarian cysts, etc.). Fourthly, determination of the hormonal status of the pregnant woman.

Morphological and functional changes in the body during pregnancy are sensitively detected by radiation methods. During the physiological course of pregnancy, hyperthermia zones in the mammary glands, anterior abdominal wall (especially above the pubis), and neck are already determined on thermograms in the early period. Radioimmune tests, reflecting the hormonal restructuring of the body, are even more sensitive. However, ultrasound methods have acquired a leading role in radiation diagnostics. Currently, most medical institutions implement screening programs for examining all pregnant women. Based on a combination of clinical, ultrasound, and radioimmunological data, a conclusion is made about the nature of the course of pregnancy and the need for any treatment and preventive measures.

Sonography is one of the most accurate methods of establishing the fact of pregnancy. Already in the 5th-6th week of pregnancy, an image of the fertilized egg appears on sonograms. It is located in the uterus asymmetrically and has the appearance of a cavity with an echo-negative center and an echogenic rim.

In a normal pregnancy, unlike an ectopic pregnancy, the outline of the fetal sac consists of two rings inscribed one inside the other. At the 6th week, the fertilized egg occupies 1/3 of the uterine cavity, at the 8th-9th week - almost half of it. Unevenness in the thickness of the villous membrane appears, caused by the formation of the placenta. Image details are best distinguished by transvaginal sonography. From the 8th-9th week, the yolk sac begins to be visualized as a spherical formation with a diameter of 5-6 mm. An image of the embryo can be obtained at the 7th-8th week, and this is a sign of the normal course of pregnancy. The embryo is located near the wall of the amnion, has a size of 9-10 mm. During this period, it is already possible to examine the activity of its heart.

As the embryo develops further, all its main structures become apparent. At 9-10 weeks, the head and body begin to appear, at 10-11 weeks - the limbs and umbilical cord. At 12 weeks, an ultrasound signal from the midline structures of the brain (M-echo) is detected. M-echo serves as a reference point in the diagnosis of a number of pathological changes in the fetal brain. The placenta is quite clearly visible at 8-10 weeks; at 12 weeks, it has the appearance of a homogeneous echogenic mass.

Using ultrasound in the energy Doppler mode, the activity of the heart and stomach is studied from the 10th week of pregnancy. Around the same time, slow fetal movements are recorded. Later, rapid jerky movements appear, which are accompanied by limb movements. Incidentally, we note that parts of the fetal skeleton are visible on X-rays no earlier than the 13th-14th week.

The gestational age is determined by ultrasound measurement of the uterus, fertilized egg and embryo. The uterus begins to increase by 7-10 mm per week from the 7th week of pregnancy. Based on the results of ultrasound biometry, the gestational age in the first trimester can be determined with an accuracy of up to 1 week using special tables. Reliable data for this can be obtained by measuring the fertilized egg. Its weekly increase is 5-8 mm. The accuracy of calculating the gestational age based on the fertilized egg is ±4-7 days. An important indicator is also the results of fetometry - measurements of the fetus, especially between the 10th and 26th weeks. There are tables indicating various fetal parameters at different periods of pregnancy.

There are also tables that summarize the dimensions of the fetus in the X-ray image, as well as the timing of the appearance of ossification points in the various bones visible on the X-ray images. However, X-rays are only allowed for special indications and are absolutely prohibited during the first trimester of pregnancy, when the fetus is especially sensitive to the effects of ionizing radiation.

The sex of the fetus can be determined between 24 and 34 weeks. Sonograms taken during this period show images of the scrotum and penis in boys. At later stages, these organs are more difficult to detect due to the larger size of the fetus and the reduced volume of amniotic fluid.

It is important for an obstetrician to know the location and condition of the placenta. The placenta is visible on sonograms at the beginning of the second trimester of pregnancy as a flat, echo-positive formation of a granular structure. Its border facing the amniotic fluid is clear, while the base facing the uterine wall is not clearly outlined. In the third trimester, individual lobes of the placenta become visible. The maximum thickness of the placenta - 35-40 mm - is achieved by the 35th week of pregnancy. Then the placenta becomes somewhat thinner and flatter. Flattening at an earlier stage is an unfavorable sign. It is observed in polyhydramnios, fetal hypotrophy, hemolytic disease of the fetus, and some of its anomalies. In all these cases, in parallel with the thinning of the placenta, the concentration of placental lactogen and progesterone in the blood decreases.

Of great practical importance is the determination of the relationship between the lower edge of the placenta and the internal os of the cervix. Normally, this distance should not be less than 7 cm. Otherwise, we speak of a low location or partial placenta previa. Such women often experience bleeding. In this regard, in the case of a stable position of the placenta near the cervix, the pregnant woman is included in the high-risk group and is hospitalized for medical observation 2 weeks before the expected birth. Complete placenta previa, when the latter covers the cervical os, poses a particular danger in terms of uterine bleeding.

An ultrasound sign of a threatened miscarriage is a periodically occurring local thickening of the muscular wall of the uterus, which deforms the fertilized egg. A symptom of a beginning miscarriage is the detachment of the fertilized egg from the wall of the uterus. This is clearly visible on the sonogram, as an echo-negative strip appears, caused by the spilled blood. A decrease in the concentration of placental lactogen, estriol and progesterone in the blood confirms the beginning of a miscarriage.

One of the most severe complications of pregnancy is intrauterine fetal death. Radioimmunological studies reveal low concentrations of placental lactogen and progesterone.

Ultrasound examination helps in diagnosing ectopic pregnancy. A reliable sign of it is the detection of a fertilized egg and embryo outside the uterus with an "empty" uterus, i.e. not containing these formations. If a woman does not have abundant bloody discharge, then 10 ml of isotonic sodium chloride solution can be introduced into the cervical canal. In case of ectopic pregnancy, sonograms clearly show the echo-negativity of the uterine cavity and tubes. A radiographic sign of ectopic pregnancy is also the localization of the fetus outside the uterus.

For obstetricians, knowledge of radioimmunological indicators of normal and abnormal pregnancy is of considerable importance. During pregnancy, a unique endocrine system of the fetoplacental complex is formed in the woman's body, which corrects the complex relationship between mother and fetus. The main products of the fetoplacental system are steroid galactotropic and somatotropic hormones.

The most important measurement for assessing the function of the placenta and the condition of the fetus is the determination of the level of placental lactogen (PL), alpha-fetoprotein (AFP), progesterone and estriol.

The favorable course of labor may be hindered by the incorrect position of the fetus, the discrepancy between the size of the fetus and the size of the pelvis, various anomalies and diseases of the woman's birth canal. Timely diagnosis of these conditions is carried out by ultrasound scanning and magnetic resonance imaging. The capabilities of sonography are discussed above. Here we note that the use of magnetic resonance imaging opens up broad prospects for the obstetric clinic, since the analysis of magnetic resonance tomograms can obtain comprehensive information about the uterus, ovaries, the condition of the fetus, placenta, soft tissues of the birth canal without irradiating the mother and fetus. In the absence of modern technical means, the size of the pelvis and the position of the fetus can be determined using an X-ray method, including X-ray pelvimetry - measuring the size of the pelvis and the head of the fetus using X-rays. Various X-ray measurement methods have been developed for this purpose. We emphasize that the referral of a pregnant woman for X-ray imaging should be justified and recorded in the outpatient card or birth history. Interventional radiation methods of examination and correction of the fetus' condition are gradually entering practice - fetal radiation surgery is being formed. Under the control of ultrasound scanning, early amniocentesis, chorion biopsy, fetal blood sampling (for the diagnosis of hemophilia, thalassemia and other lesions), fetal skin biopsy, treatment of obstruction of the urinary tract, etc. are carried out.

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