Uterine contractile activity in pregnant women with preliminaries

The data available in the literature on uterine contractility in the preliminary period are few and contradictory. This probably explains the clinical data. F. Arias (1989) cites E. Friedman's data and identifies the latent phase of labor with the preparatory period according to Friedman. The average duration of the latent phase (preparatory period according to Friedman) in primiparous women is 8.6 hours, and in multiparous women - 5.3 hours. A prolonged latent phase can be discussed in cases where it is equal to 20 hours in primiparous women and 14 hours in multiparous women. The most frequent problems associated with the diagnosis of a prolonged latent phase are difficulties in determining the time of the onset of labor and the onset of the active phase. In many cases, it is difficult to distinguish between false labor and its latent phase. The problem of differential diagnosis between the latent phase of labor and false labor does not play a decisive role as long as the obstetrician avoids such active interventions as amniotomy or labor stimulation. In fact, both false labor and a prolonged latent phase are harmless conditions, and expectant management does not harm either the child or the mother. In contrast, intervention can lead to a number of complications and, consequently, to perinatal and maternal morbidity.

The best criterion for recognizing false labor and excluding a prolonged latent phase is a retrospective assessment of these conditions. If a pregnant woman with regular contractions without uterine changes stops labor after the administration of 0.015 morphine or 0.2 g secobarbital, we can talk about false labor. Unfortunately, retrospective diagnosis cannot be applied in practice. The best way to exclude such errors is to accurately determine the time of onset of labor. False labor is observed in approximately 10% of primiparous women with an initial diagnosis of a prolonged latent phase, while in multiparous women with the same diagnosis, it is observed in more than 50% of cases. The difference in the frequency of false labor indicates how difficult it is to establish the onset of labor in multiparous women.

A comparative analysis of the contractile activity of the uterus during the normal and pathological course of the preliminary period revealed the following characteristic features:

• a doubling of the number of contractions in the lower segment of the uterus in both primiparous and multiparous women;
• an increase in the amplitude of uterine contractions by 2 times in all parts of the uterus, especially pronounced in primiparous women and tending to increase in multiparous women; the form of contraction does not exceed 0.5 (coefficient according to G. G. Khechinashvili and T. A. Gusarova);
• an increase of 1.5 times in the duration of uterine contractions in the area of the lower segment of the uterus and a decrease in the area of the fundus and body of the uterus; accordingly, the pauses between uterine contractions are longer in the area of the fundus and body of the uterus and 2 times shorter in the area of its lower segment.

The preliminary period occurs due to the development of uncoordinated contractions of the uterus, and the signal of their occurrence should be considered cramping or aching pain in the lower abdomen. However, the intensity and nature of the pain, its duration depend on the stage of uncoordination and the speed of its development. Thus, in the initial stages, contractions of the longitudinal muscles prevail over the circulatory ones and therefore the pain is moderate, tolerable. If the contractile function is not normalized in the initial stages, stage II develops consistently, in which the tone of the circulatory muscles already prevails and the pain intensifies, causing a feeling of anxiety, poor sleep, increased blood pressure and other phenomena.

In order to prevent uncoordinated uterine contractions, it is recommended to identify high-risk women in antenatal clinics during pregnancy and before childbirth, study the nature of the contractile function of the uterus, conduct psychophysical, pharmacological and other types of preparation, and promptly refer pregnant women to hospital. During the preliminary period, hysterography reveals a violation of the so-called "triple descending gradient" of uterine contractions and abnormalities in placental attachment. It has also been established that the pathological course of the preliminary period most often manifests itself at night and requires correction taking into account the maturity of the cervix, in particular, a glucose-calcium-estrogen-vitamin background and electroanalgesia are recommended.

A prognostic map of the risk of developing weakness of labor activity and a method for its prevention in the preparatory period for childbirth have been developed. According to the author, age (30 years and older), obesity of II-III degree, genital infantilism, post-term pregnancy, pathological course of the preliminary period and especially a combination of these factors are of the greatest importance.

In order to predict the risk of developing uterine contractile dysfunction during labor in women with rheumatic heart defects, diagnostic algorithms and differential diagnostic tables have been developed taking into account the coefficient of information content of various signs. To prevent uterine contractile dysfunction, it is recommended to use the therapeutic nutritional preparations "Antihypoxin", "Unityol", "Antioxidant", and ethimizol in the prenatal period.

It is necessary to differentiate between the indicators of uterine contractile activity during the normal and pathological preliminary period, since the tactics of managing pregnant women with the justification for prescribing appropriate therapy depend on this.

The normal preliminary period is characterized by a clear decrease in the number of contractions and their duration from the bottom to the body and lower segment in both primiparous and multiparous women (on average, from 8 to 5 contractions per hour in primiparous women and from 7 to 3 in multiparous women with a fluctuation of ± 1 uterine contraction).

In the pathological preliminary period, a distinctive feature is an increase in the number of contractions by 2 times only in the lower segment of the uterus in primiparous women and by 3 times in multiparous women.