Methods of preparing pregnant women for childbirth

The state of readiness for childbirth is most clearly revealed by changes found in the woman’s reproductive system.

Determination of cervical maturity

To diagnose changes that occur during the formation of readiness for childbirth in a woman's body, the following tests are most widely used:

• determination of cervical maturity;
• study of the physical and chemical properties of cervical mucus;
• clarification of the parameters of uterine contractile activity and its sensitivity to oxytocin;
• cytological examination of vaginal smears and others. However, of all the listed tests, the most reliable and easy to perform is the method of palpation of the maturity of the cervix. In this case, attention is paid to the consistency (degree of softening) of the cervix, the length of its vaginal part, the degree of gaping of the cervical canal, the position of the cervix in relation to the pelvic axis. With a gaping cervical canal, the degree of its patency is determined, as well as its length, comparing this indicator with the length of the vaginal cervix: the smaller the difference between the noted indicators, the more pronounced the maturity of the cervix.

All the above mentioned signs are the basis of the classification developed by Professor G. G. Khechinashvili. According to this classification, the following four types of cervical conditions should be considered.

1. The immature cervix is softened only at the periphery and dense along the cervical canal, and in some cases dense entirely; the vaginal part is preserved or slightly shortened. The external os is closed or allows the tip of a finger to pass through; the vaginal part appears "fleshy", the thickness of its wall is about 2 cm. The cervix is located in the cavity of the small pelvis, away from the pelvic axis and its midline, its external os is determined at a level corresponding to the middle of the distance between the upper and lower edges of the pubic symphysis or even closer to its upper edge.
2. The ripening cervix is not completely softened, a dense tissue area is still visible along the cervical canal and especially at the level of the internal os. The vaginal part of the cervix is slightly shortened, in primiparous women the external os allows the tip of a finger to pass through, or less often the cervical canal is passable for a finger to the internal os, or with difficulty beyond the internal os. Note the significant difference (more than 1 cm) between the length of the vaginal part of the cervix and the length of the cervical canal. There is a sharp transition of the cervical canal to the lower segment in the area of the internal os.

The presenting part is not palpated clearly enough through the vaults. The wall of the vaginal part of the cervix is still quite thick (up to 1.5 cm), the vaginal part of the cervix is located away from the pelvic axis. The external os is determined at the level of the lower edge of the symphysis or slightly higher.

3. Not fully matured cervix - softened almost completely, only in the area of the internal os is a section of dense tissue still defined, the canal is passable in all cases for one finger behind the internal os, with difficulty in primiparous women. There is no smooth transition of the cervical canal to the lower segment. The presenting part is palpated through the vaults quite clearly.

The wall of the vaginal part of the cervix is noticeably thinned (up to 1 cm), and the vaginal part itself is located closer to the pelvic axis. The external os is determined at the level of the lower edge of the symphysis, and sometimes lower, but does not reach the level of the ischial spines.

4. The mature cervix is completely softened; shortened or sharply shortened, the cervical canal freely passes one or more fingers, is not curved, smoothly passes to the lower segment of the uterus in the area of the internal os. The presenting part of the fetus is palpated quite clearly through the vaults.

The wall of the vaginal part of the cervix is significantly thinned (up to 4-5 mm), the vaginal part is located strictly along the pelvic axis; the external os is determined at the level of the ischial spines.

If poor or insufficiently expressed maturity of the cervix is detected (especially in its first and second varieties), spontaneous onset of labor in the near future is unrealistic. In women with uncomplicated pregnancy, poor or insufficiently expressed maturity of the cervix is detected by the time labor begins in only 10% of cases. In all these women, spontaneously started labor acquires a pathological - protracted course due to the development of discoordinated labor with manifestations of cervical dystopia.

Signs of uterine maturity can be expressed in points and a prognosis index can be calculated

Sign	Points
	1	2	3
Position of the cervix in relation to the pelvic axis	To the sacrum	Middle	In the wire line
Cervical length	2 cm and more	1 cm	Smoothed out
Cervical consistency	Dense	Softened	Soft
Opening of the external os	Closed	1-2 cm	3 cm
Location of the presenting part of the fetus	Above the entrance	Between the upper and lower edges of the pubis	The lower edge of the pubis and below

If the score is 0-5 points, the cervix is considered immature; if the score is more than 10 points, the cervix is mature (ready for labor) and labor induction can be used.

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Evaluation of the tone and contractility of the uterus

In order to register the tone of the uterus and its contractile activity in pregnant women and women in labor, many methods have been proposed, known as external and internal hysterography methods.

Internal hysterography methods allow us to judge the contractile activity of the uterus based on intrauterine pressure indicators.

Less difficult to use and completely harmless are methods of external hysterography (tocography), based on the use of various sensors applied to the abdominal wall.

The vast majority of these methods do not give an accurate idea of the tone and contractile activity of the uterus. External hysterography methods mostly allow us to judge only the frequency of contractions and partly their duration, and with multichannel recording - the coordination of contractions of various parts of the uterus. Recently, the most common method is cardiotocography.

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Determination of uterine sensitivity to oxytocin

It is known that the reactivity of the uterus to oxytocin gradually increases as pregnancy progresses and reaches a maximum immediately before labor. In 19S4, Smith was the first to use this phenomenon, developing a special test for determining the reactivity of the myometrium to the intravenous administration of a threshold dose of oxytocin capable of causing uterine contraction. Subsequently, he called this dose the oxytocin test or the test of uterine sensitivity to oxytocin, the method of which is as follows.

Before using the test, the woman being tested should be in a horizontal position for 15 minutes, in a state of complete emotional and physical rest to exclude the possibility of uterine contractions under the influence of various factors. Immediately before the test, a solution of oxytocin is prepared at the rate of 0.01 action unit (AU) of the drug per 1 ml of isotonic sodium chloride solution, 10 ml of this solution is drawn into a syringe and an intravenous injection is started. The author does not recommend starting the administration of the oxytocin solution immediately after venipuncture, since the latter itself can cause uterine contractions. The author recommends administering the solution "in jerks" of 1 ml at a time with intervals of 1 minute between each such administration. In general, no more than 5 ml of the solution can be administered. The administration of the solution should be stopped when a reaction of the uterus (its contraction) occurs.

The test is considered positive if oxytocin-induced uterine contraction occurs within the first 3 minutes from the start of the test, i.e. as a result of the introduction of 1, 2 or 3 ml of the solution. Uterine contractions are recorded either by abdominal palpation or by one of the hysterography methods.

According to Smith, a positive oxytocin test indicates the possibility of spontaneous labor in a woman within the next 1-2 days. The author recommends using the oxytocin test also to determine a woman's readiness for labor before inducing labor for early delivery for one reason or another. The uterine reactivity to oxytocin when using this test does not depend on the age of the woman being tested or whether she is giving birth for the first time or repeatedly.

The oxytocin test has found quite wide application both in clinical practice and in scientific research.

Some authors have slightly modified the oxytocin test technique developed by Smith. Thus, Baumgarten and Hofhansl (1961) consider it advisable to administer oxytocin solution intravenously not "in bursts", but gradually, at 0.01 U in 1 ml of isotonic sodium chloride solution per 1 min. From the point of view of these authors, this method of administering oxytocin solution is more physiological and prevents the possibility of tetanic contraction of the uterus. Klimek (1961), taking Smith's original technique as a basis, proposed judging by the number of ml of administered oxytocin solution (capable of causing uterine contraction) how many days, counting from the day of the test, spontaneous labor should be expected. Thus, if uterine contraction occurs after intravenous administration of 2 ml of oxytocin solution (0.02 U), labor should occur in 2 days.

Thus, according to the above studies, the oxytocin test is valuable for diagnosing a woman’s readiness for childbirth and determining the conditions for inducing labor if early termination of pregnancy is necessary.

Recently, it has become common practice to conduct the so-called oxytocin stress test before inducing labor, which makes it possible to assess not only the readiness of the uterus for contractile activity, but also to determine the condition of the fetus.

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Cytological examination of vaginal smears

It is now generally accepted that the method of cytological examination of vaginal smears can be used to determine qualitative shifts in the hormonal balance of a woman's body during pregnancy and especially before labor. There is extensive literature devoted to this issue.

For completeness of judgments about qualitative changes in the composition of cells of the vaginal contents of a woman in the dynamics of pregnancy, it is necessary to use polychromy of smear staining, allowing to differentiate cyanophilic cells from oestrogens. It is generally accepted that detection of predominantly cyanophilic cells in a smear indicates the prevalence of progesterone activity over estrogens. And vice versa, an increase in the content of oestrogens indicates an increase in estrogen activity.

In recent years, the method of fluorescent microscopy of vaginal smears has found application. However, despite the relative simplicity and speed of its implementation, the negative side of this method, as well as the method using conventional (monochrome) staining of smears, is that both of them do not allow one to judge the change in the quantitative content of cyanophilic and eosinophilic cells.

During pregnancy, especially starting from the second trimester, there is a proliferation of the basal layer of the epithelium and an expansion of the intermediate layer with a simultaneous decrease in the number of cells of the superficial layer. All these changes are associated with the increasing activity of placental steroids and especially progesterone. By this time, the navicular cells characteristic of pregnancy appear, originating from the intermediate layer of the vaginal epithelium. A distinctive feature of the navicular cells is the vacuolization of the cytoplasm due to the accumulation of glycogen in it, as well as pronounced cyanophilia. A significant predominance of navicular cells, cyanophilically stained and closely adjacent to each other, is observed in physiologically proceeding pregnancy up to 38-39 weeks.

Beginning with the 38th-39th week of pregnancy (approximately 10 days before the expected birth), changes in the cytological picture of the vaginal smear appear and then become more and more pronounced, attributed to an increase in the activity of estrogenic hormones with a simultaneous decrease in the activity of progesterone. As labor approaches, the number of boat-shaped cells typical of a progressive pregnancy decreases with an increase in the number of cells in the superficial layers, increasingly stained eosinophilically and containing pycnotic nuclei. At the same time, a rarefaction of cellular elements, a decrease in the ability of epithelial cells to perceive dye and the appearance of an increasing number of leukocytes are also observed.

An assessment of the listed cellular elements makes it possible to determine the belonging of each studied smear to one of the four cytotypes given in the classification of Zhidovsky (1964), and to judge the degree of biological readiness of a woman for childbirth.

Below is a brief description of the microscopic data of vaginal smears typical for each cytotype; at the same time, the expected time of delivery characteristic for each cytotype is indicated.

• I cytotype: "late pregnancy" or "navicular smear type" is typical for normally progressing pregnancy, starting from its second trimester. The smear is dominated by boat-shaped and intermediate cells in a ratio of 3:1 in the form of characteristic clusters. The cytoplasm of such cells is sharply cyanophilic. There are almost no superficial cells in the smear. Leukocytes and mucus are usually absent.

Eosinophilic cells are found in an average of 1% of women, and cells with pyknosis of nuclei - up to 3%.

The onset of labor with this cytotype of smears should be expected no earlier than 10 days from the day they were taken.

• II cytotype: "shortly before birth". In a smear of this type, a decrease in the number of boat-shaped cells is found with a simultaneous increase in the number of intermediate cells proper, and their ratio is 1:1. The cells begin to be located more isolated, and not in the form of clusters, as is observed in a smear typical for I cytotype.

The number of superficial cells increases, and among them the number of eosinophilic cells and cells with pyknosis of nuclei increases slightly (up to 2% and up to 6%, respectively).

The onset of labor with this smear type should be expected in 4-8 days.

• III cytotype: "delivery period". In a smear of this type, intermediate cells (up to 60-80%) and superficial cells (up to 25-40%) predominate, having vesicular or pyknotic nuclei. Boat-shaped cells are found only in 3-10%. There are no clusters of cells, and the latter are located in isolation. The content of eosinophilic cells increases to 8%, and cells with pyknosis of nuclei - to 15-20%. The amount of mucus and leukocytes also increases. Cell staining is reduced, and their contours are less contrasting.

The onset of labor with this smear cytotype should be expected in 1-5 days.

• IV cytotype: "certain term of delivery*. Smears show the most pronounced regressive changes: superficial cells predominate (up to 80%), boat-shaped cells are almost absent, and intermediate cells are present in small quantities. Superficial eosinophilic cells sometimes lose their nuclei and look like "red shadows". In most cases, the cytoplasm is poorly stained, the edges of the cells are low-contrast, and the smear takes on a "erased" or "dirty" appearance. The number of eosinophilic cells increases to 20%, and cells with pycnosis of nuclei - up to 20-40%. The number of leukocytes and mucus in the form of clusters also increases noticeably.

With this type of smear, labor should occur on the same day or, at the very least, within the next three days.

Changes in some physical and biochemical properties of the secretion of the glands of the cervix at the end of pregnancy as an indicator of the readiness of the woman's body for childbirth

Pregnant women, unlike non-pregnant women, have some peculiarities in the secretion of the glandular apparatus of the cervix. K. A. Kogai (1976) showed that at 32-36 weeks of pregnancy, in the presence of a ripening cervix, i.e. in the absence of its readiness for childbirth, there is little mucus in the cervical canal (a "dry" cervix), and it is sucked out with difficulty. In such cases, the mucus is opaque and does not crystallize when drying, i.e. there is no "fern" symptom. In addition, at these stages of pregnancy, compared with later ones, the mucus contains a comparatively small amount of total protein. In the presence of a ripening cervix at 32-36 weeks of pregnancy, protein fractions are detected: albumin, transferrin, immunoglobulin.

As the upcoming birth approaches and the degree of maturity of the cervix increases, a distinct change in the physical and biochemical properties of mucus is observed: its quantity increases and its transparency increases. In every third woman, 1-2 days before birth, crystallization of cervical mucus is detected.

In almost full-term pregnancy and detection of a mature cervix, starting from the 38th-39th week, the content of total protein in the cervical mucus increases and a rich protein spectrum is detected. Thus, if during pregnancy of 32-36 weeks 1-3 protein fractions are detected in the mucus, then before labor it contains 8-10 such fractions.

Thus, during the maturation of the cervix, significant changes occur in the function of the glands of the cervical canal, which is manifested by a significant increase in the total amount of secreted mucus, an increase in its transparency, the appearance of a crystallization symptom, an increase in the content of total protein in it and an expansion of its spectrum. The indicated changes in the secretory function of the cervical glands can apparently be used as an additional test in assessing the degree of readiness of the woman's body for childbirth.

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