Rationale for the use of dual-channel internal hysterography

The prognosis of labor and the strength of uterine contractions is almost impossible. Some authors begin to use uterotropic agents (oxytocin, prostaglandins) in labor when uterine activity, according to internal hysterography, does not exceed 100 units during an hour. Montevideo. The problem of uterine motor function disorders in terms of its regulation is mainly solved empirically in the clinic and therefore today we cannot talk about the regulation of labor activity only because the amount of information that clinicians have about the physiology and pathology of the contractile function of the uterus is insufficient. And only the disclosure of the patterns of physiology and pathology of the motor function of the uterus can be the basis for developing dynamic schemes for regulating labor activity.

Of great importance is Pinto's opinion, based on his own research, that the mechanical concept of the relationship between uterine activity and cervical dilation is justified only for the end of the second period (the period of expulsion) and the afterbirth period, but not for the first period of labor. Long-term forecasting of uterine contractility for the vast majority of births is statistically invalid. In addition, the author claims that the significant unevenness of the qualitative and quantitative indicators of uterine contractility during labor, combined with significant individual variability in the dynamics and duration of the main phases of labor, significantly complicates the generalized partographic and tocographic characteristics of labor as a whole.

Other authors also point out the high individual variability of the indices of uterine contractile activity during spontaneous and induced labor. Particular attention is paid to the evaluation of the symmetry of the uterine contraction waveform recorded during different stages of labor with different durations of the contraction phase and relaxation phase of the uterus.

Spontaneous changes in uterine contractility are reported, that it does not always maintain the same type of activity during labor, and in fact its type of activity often changes. During normal labor, a series of normal waves is observed, alternating with periods of uncoordinated labor or with ascending waves of uterine contractions. When these waves predominate, the progress of labor slows down. During normal labor, synergism of contractions of all parts of the uterus is revealed with the manifestation of the "triple descending gradient" according to Reynolds at 2-3 cm of cervical dilation. At 4-6 cm of cervical dilation, reciprocity in uterine contractility usually occurs, manifested by relaxation of its lower segment with simultaneous contraction of the fundus and body of the uterus. In the culmination phase of the dilation period, all parts, including the lower segment, actively contract with the preservation of the "triple descending gradient". In case of weak labor activity, the authors found that already at 2-3 cm of cervical dilation, relaxation of the lower segment of the uterus was observed and earlier occurrence of contractions in the area of the body or lower segment was noted than in the area of the fundus on the left.

From the data presented it is evident that to date the mechanisms of self-regulation of the uterus during pregnancy and childbirth that lead to a successful completion of childbirth are not known.

We have developed a method of two-channel internal hysterography, indications and justification for its use in labor. Two catheters are inserted transcervically: the first one at a length of 42-41 cm from the entrance to the vagina and the second one - into the area of the lower segment of the uterus at 20-21 cm from the entrance to the vagina. Contraindications for the use of this method are abnormalities of placental attachment and fever during labor.

The rationale for the use and development of dual-channel internal hysterography was the following circumstances. The lower segment of the uterus, compared to the body, is an independent section of the uterus with certain boundaries both macro- and microscopically, as well as certain anatomical and functional features. The body of the uterus has 4 layers, and the lower segment has two sections - external and internal.

We have identified a difference in the values of intrauterine pressure in the area of the fundus and lower segment of the uterus, which depends mainly on two physical factors: the height of the hydrodynamic column and the angle of inclination of the longitudinal axis of the uterus to the horizontal line. The difference in pressure in the specified sections of the uterus at different angles of its inclination to the horizontal line can fluctuate from 5 mm Hg (at an angle of 10) to 29 mm Hg at an angle of 90.

The second very important point of this method is that, knowing the value of intrauterine pressure developed by the lower segment of the uterus, it is possible to easily calculate the force that facilitates the advancement of the presenting part along the birth canal during normal and complicated labor and the detection of deviations in the contractile function of the uterus, control and regulate these processes with various medications or methods (changing the position of the woman in labor, etc.). We have carried out a hydrodynamic calculation of the force that facilitates the advancement of the head along the birth canal during normal and complicated labor, which allows us to avoid birth trauma to the mother, fetus and newborn child.

Thanks to the developed method of two-channel internal hysterography, a functional hydrodynamic cavity in the area of the lower segment of the uterus, formed during contractions and limited by the wall of the uterus in the lower segment, the shoulders of the fetus and the head of the fetus, was discovered for the first time.

The presence of this functional hydrodynamic cavity is proven by the zone of increased intrauterine pressure during the registration of contractions by two-channel internal hysterography in the area of the lower segment of the uterus due to its active contraction during the contraction, otherwise there would be no zone of increased pressure. In addition, the presence of a hydrodynamic cavity was also revealed during radiography of the uterus and fetus in the first period of labor with the introduction of 120 ml of verografin diluted 2 times with isotonic sodium chloride solution into the uterine cavity. On radiographs in the area of the lower segment of the uterus, a cavity with clear contours was revealed, which did not communicate with the rest of the uterus at the time of contraction. This functional cavity in the area of the lower segment of the uterus is of great importance in the mechanisms of self-regulation of the uterus during labor.

Scientific and practical use of two-channel internal hysterography and the phenomenon of the functional hydrodynamic cavity in the lower segment of the uterus. In the field of scientific use, there is an opportunity for theoretical development of the causes of various types of labor anomalies. Based on a comparison of intrauterine pressure data and the location of the placenta (in the fundus, body or lower segment of the uterus), one can try to clarify the question of why different durations of labor are observed, taking into account the hydrodynamic cavity. Based on theoretical calculations, it is possible to calculate the optimal values based on the intrauterine pressure data developed in the fundus and lower segment of the uterus, at which normal labor will be observed. It is possible to study the effect of various agents on different parts of the uterus (tonotropic agents, antispasmodics, painkillers, epidural anesthesia, etc.).

The method of two-channel internal hysterography is used for the purposes of early diagnosis of weakness of labor activity and prognosis of labor based on the ratio of the strength of uterine contractions and coordination of contractions in the lower segment of the uterus and its fundus.

It has been established that the normal course of labor is observed with a sufficiently high activity of the lower segment of the uterus. In addition, thanks to the information revealed about the values of intrauterine pressure in the area of the fundus and lower segment of the uterus, it is possible to physically calculate the force of contraction that will be sufficient to advance the presenting part and at the same time help prevent birth trauma for both the mother and the newborn. Newborn trauma remains high to this day.

The most common type of birth trauma remains a clavicle fracture (56.8%) in large babies and with abnormal labor. Birth trauma in children remains quite high, despite the expansion of indications for cesarean section in the interests of the fetus, the use of various means during labor that regulate labor. Calculation of the labor forces required to advance the presenting part allows for a more reasonable use of various antispasmodic and other means during labor, as well as the development of optimal doses, method and time of administration of drugs, taking into account the nature of labor.

An important direction is the further study of the biomechanism during physiological and pathological births and the clarification, using this technique, of the role of the lower segment of the uterus in the biomechanism of birth, the reasons that determine the configuration of the head, the internal rotation of the head, etc.

Of practical importance is the decrease in the frequency of contractions during normal labor and when the cervix opens to 4-7 cm, which indicates elements of self-regulation of the uterus.

It is also extremely important to study the motor function of the uterus in the afterbirth period, especially with a simultaneous study of the blood coagulation system. As has been shown in studies, with uterine hypotension, there are disturbances in the coordination of the upper and lower segments of the uterus. In cases with pathological blood loss, uterine contractions were rare, short-lived, and there was a noticeable lag in contractions of the lower segment from those of the upper. In the absence of pathological blood loss, uterine contractions were frequent, long-lasting, and contractions of the lower segment of the uterus did not lag behind contractions of the upper, i.e. the ratio was 20 and 24 (lower segment), and then also 23 and 25, 26 and 24, 31 and 30 mm (intensity of contractions), respectively.

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