Stopping the lower part of the fetus

As is known, the most significant lowering of the presenting part of the fetus occurs at the end of I and especially in the second stage of labor. Therefore, the impossibility of further fetal progression, stopping or slowing down of the fetus are typical violations of the II period of labor. The dropping is noted when the fetus does not move through the birth canal within 1 h, which can be determined by the results of vaginal examinations performed at the appropriate time interval.

Diagnostics. To establish the diagnosis, it is necessary to conduct at least 2 vaginal examinations. Determination of the nature of fetal progression in the small pelvis of a woman in childbirth is complicated by the fact that changes in the shape of the fetal head (configuration) occur at the end of the birth, which increases the probability of errors. In many cases, with vaginal examination, there was an impression that there was a positive dynamics, whereas this was due only to the appearance of a birth tumor or the configuration of the head.

Errors of this kind are so common that E. Friedman recommends that in all parturient women with suspected anomalies of lowering the fetus determine the height of standing of his present part simultaneously with external obstetric and vaginal examinations.

To determine the nature of the lowering of the fetal part of the fetus during external obstetric examination, Leopold's 1st and 2nd procedures should be performed and the height of the standing part of the fetus within the range of -5 (the head movable) to +5 (the head deep in the small pelvis) . This method is less accurate in comparison with the evaluation of the standing of the fetus's present part, carried out with the help of a vaginal examination. Applying both methods simultaneously, it is possible to minimize the errors that arise in connection with the configuration of the fetal head.

Frequency. Stopping the lowering of the presenting part of the fetus occurs in approximately 5-6% of births.

Causes. There are three main reasons for stopping the lowering: mismatch of fetal and pelvic dimensions of the mother, improper presentation of the fetus and regional anesthesia.

In the first-born, the discrepancy between the size of the fetus and the pelvis of the mother causes this complication in more than 50% of cases. This is observed even more often if a stop occurs when the standing part of the fetus is high or the mother is stimulated with oxytocin. E. Friedman et al. (1978) reported that during epidural anesthesia, 80.6% of the primiparas were subsequently followed by a stopping of the lowering of the presenting part of the fetus. Thus, epidural anesthesia serves as an additional factor contributing to the development of this complication.

Similarly, an incorrect presentation of the fetus (with the occiput turned posteriorly) was noted in 75.9% of women with a stopping of the lowering of the fetus. However, almost all primigravens with incorrect presentation of the fetus had other simultaneously acting factors. In connection with this, it is difficult to single out the independent role of incorrect presentations as an etiological factor in stopping the lowering of the presenting part of the fetus.

In the case of multi-fetuses with stopping the fetal movement through the birth canal, the incidence of mismatch between the fetus and the pelvis of the parturient woman is only 29.7%. The frequency of improper presentation of the fetus or the application of ziduralnoy anesthesia is the same as in the primipara.

Forecast. Pregnant women with a stopping of the lowering of the fetal part about the prognosis should be judged with caution. This is mainly due to the fact that with this anomaly of labor activity, a very frequent etiological factor is the mismatch between the size of the fetus and the pelvis of the mother. E. Friedman et al. (1978) showed that 30.4% of parturient women with a stopping of fetal lowering required a cesarean section, 37.6% - imposition of obstetric forceps (cavitary), 12.7% - rotation of the head in forceps; in 5.1% of women the use of forceps has not been successful.

The following are the most important prognostic signs in women in labor with the stopping of the presenting part of the fetus:

• the level of standing of the presenting part of the fetus at the moment of stopping (the higher the standing, the greater the probability of a discrepancy between the size of the fetus and the pelvis of the mother);
• the duration of the stop (the more it is, the higher the probability of a mismatch between the size of the fetus and the pelvis of the mother);
• the nature of the lowering of the presenting part of the fetus after a stop (if the rate of lowering it after stopping is the same or more than before it, you can give a good prognosis of normal atraumatic births).

Stopping the lowering of the fetus is accompanied by a significant maternal and perinatal morbidity, regardless of whether surgical intervention was required. The most common complication is bleeding after childbirth (12.5% of cases). The threatening condition of the fetus, judging by low estimates on the Apgar scale, is a common complication (21.9%). The difficult birth of the shoulder girdle (dystopia of the shoulders) and the associated increased morbidity (Erba's paralysis, fracture of the collarbone, fetal injuries, etc.) are observed in 14.1% of cases.

Keeping the birth when the lowering of the lower part of the fetus is stopped

After the diagnosis of stopping the lowering of the presenting part of the fetus, the first steps should be aimed at revealing the etiological factors. However, the presence of such obvious causes as epidural anesthesia or a false presentation of the fetus should not lead the physician away from the need to evaluate the ratio of the fetal and pelvic dimensions of the mother. Gillis-Muller's method should be applied, and if free movement of the fetal part is recorded, eliminating the discrepancy of the dimensions, it is possible to start looking for other factors. With a negative Gillis-Muller test, it is necessary to urgently perform pelvimetry, and if there is a discrepancy between the size of the fetus and the pelvis of the mother - a caesarean section.

If clinical data and pelvimetry data exclude a mismatch between fetal and pelvic maternal size, follow-up care includes monitoring the maternity patient in anticipation of weakening sedation, regional anesthesia (if used), or stimulation of uterine contractions. Both approaches require careful monitoring of the condition of the mother and fetus (intrauterine pressure, pH from the fetal head, direct electrocardiography of the fetus). In the absence of a disproportion between the fetal head and the mother's pelvis, stimulation with oxytocin is indicated, starting with small doses (0.5-1.0 mU / min) with a gradual increase with intervals of at least 20 min. The effect of stimulation is observed in the next 1-1.5 hours. If this effect is not observed within 2 hours after the start of treatment, the situation should be seriously overestimated so that the possible mismatch of the fetal and pelvic dimensions of the mother does not remain unrecognized.

If there is a disproportion between the size of the fetus and the mother's pelvis, a caesarean section operation is necessary without further attempts to perform labor through the natural birth canal.

[1], [2], [3]