Prolonged latent phase of childbirth

The latent phase of labor is the time between the onset of labor and the beginning of the active phase (the rise of the curve indicating the opening of the cervix). The average duration of the latent phase in primitive women is 8.6 hours, in the case of re-parenting - 5.3 hours.

A prolonged latent phase can be talked about in cases where its duration is 20 hours in primiparas and 14 hours in reproductive women.

Diagnosis is difficult to determine the timing of the onset of labor and the beginning of the active phase. In many cases, it is difficult to distinguish between false births and the latent phase of childbirth. In addition, it is sometimes difficult to decide whether this is a prolonged latent phase or an early secondary cervical dilatation stop.

The problem of differential diagnosis between the latent phase of labor and false births does not play a decisive role as long as the obstetrician avoids such active interventions as amniotomy or stimulation of labor. Expectant tactics do 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 most adequate sign of the onset of labor should be considered smoothing and opening of the cervix.

More important is the conduct of differential diagnosis between a prolonged latent phase and an early secondary cervical dilatation. The first condition is not dangerous, whereas the second is associated with a significant risk of mismatch of the fetal size of the woman's pelvis. With the diagnosis of problems usually does not happen, if the pregnant woman was observed for several hours in the maternity hospital, as a result of which a clear rise in the curve of the opening of the cervix was registered. Problems arise, as a rule, in those cases when pregnant women arrive with a cervix of the uterus open with 3-4 cm, with pronounced smoothing of the cervix, with regular contractions of the uterus, but no further opening takes place within the next few hours. These pregnant women may have a secondary cervical dilatation stop or a prolonged latent phase. Since this differential diagnosis is impossible, it is best to start the necessary diagnostic and therapeutic measures by allowing the worst (secondary stop of the cervix opening).

Frequency. A prolonged latent phase is observed in 1.45% of the primipara and in 0.33% of maternity females.

Causes. The most frequent etiologic factor (about 50% of cases), which causes a prolonged latent phase in primiparous women, is the early and excessive use of sedatives and anesthetics during childbirth. In such cases, the restoration of the normal course of labor usually occurs after the cessation of the action of these drugs. The second cause of development of complication in primiparous women is insufficient maturity of the cervix in the beginning of childbirth. The neck remains dense, unmolded and undisclosed.

The most common cause of a prolonged latency phase in maternity females is the development of false births. If they are observed in about 10% of primiparous women with the initial diagnosis of a protracted latency phase, then in many people with the same diagnosis they are noted in more than 50% of cases. The difference in the incidence of false births indicates how difficult it is to establish the onset of labor in reproductive women.

In 75% of women with this anomaly, after the end of the latent phase, normal labor continues, resulting in normal birth. In a smaller number of women, after the end of a protracted latent phase, another anomaly develops-a secondary cervical dilatation stop (in 6.9% of parturient women) or a prolonged active phase (20.6%). When joining other anomalies of labor activity, the prognosis is unfavorable, as often (approximately in SO% of cases) a caesarean section is required. Finally, approximately 10% of women with a prolonged latent phase have false births.

Management of childbirth with a prolonged latent phase of labor

There are two approaches to the management of pregnant women with a prolonged latent phase: 1) compliance with rest and 2) stimulation of labor by oxytocin. Both methods yield approximately the same results, helping to eliminate existing violations of labor activity in about 85% of cases.

When choosing the method of management, it is necessary to take into account the degree of fatigue and anxiety of the parturient woman, the main cause of this complication (overdose of sedatives, immature cervix), and the preference for using this or that method for both the mother and the midwife.

If it is decided to select the method of resting (therapeutic sleep), the pregnant woman should intramuscularly inject 0.015 g of morphine followed by the appointment of secobarbital.

Morphine. Great experience in the clinical use of morphine showed that the drug has undoubted advantages. Morphine provides deep anesthesia, not accompanied by amnesia, does not cause myocardial sensitization to catecholamines, does not disrupt blood flow and its regulation in the brain, heart, kidneys, does not have toxic effects on the liver, kidneys and other organs. Intramuscular administration of morphine, along with subcutaneous, provides the optimal duration of its action, whereas after its intravenous administration the half-life (T _1/2 ) is only about 100 minutes. Morphine partially binds to plasma proteins. The threshold analgesic effect of the drug develops at a concentration of free morphine in the plasma of 30 ng / ml. Morphine is excreted mainly from the body through the kidneys, mainly in the form of glucuronide. In experiments it was established that morphine activity can vary by 7 times depending on the time of day and the phase of the menstrual cycle.

Morphine and other morphine-like drugs can penetrate the placenta. It was found that after intramuscular injection of the mother with 2 mg of morphine per 10 kg of body weight, the ratio of the concentrations of the drug in the fetus and in the maternal body increases for approximately 1/2 h. In the mother, the maximum concentration of morphine in the blood plasma was reached 1 h after this injection. Morphine penetrates into breast milk only in small amounts, and at therapeutic doses they do not have a significant effect on the baby.

Promedol - a domestic synthetic analogue of meperidine - is 5-6 times less active than morphine, with various methods of administration. Promedol is more safe for the fetus. But it should be remembered that after the administration of promedol (meperidine) during labor, the fetus may develop harmful effects, depending on the time of administration of the drug to the mother. Therefore, during birth, narcotic analgesics should be administered only in the first half of the first stage of labor or in the event that the birth of the child should occur within the next hour. Moreover, promedol gives some rhodostimulating effect, favorably affects the blood circulation in the pregnant uterus, which allows us to consider it as a means of choice in the obstetric clinic.

Secobarbital sodium (seconal) - Barbiturate short-acting. Sleeping effect with a single administration has 100-200 mg of the drug. Produced in the form of tablets of 100 mg, an elixir of 4 mg / ml and in injections of 250 mg. Secobarbital has a short hypnotic effect (less than 4 hours).

Treatment with these drugs is effective: the vast majority of women fall asleep within 1 hour after its inception and wake up in 4-5 hours with active labor or without any of its signs. This may be due to opioid inhibition of the release of oxytocin from the posterior lobe of the pituitary gland under the influence of opiates like morphine and opioid peptides - beta-endorphin and enkephalin analogues.

With such treatment there is a danger to face two possible problems. The first of them consists in the erroneous appointment of a large dose of narcotic drugs to a woman with an active phase of labor that already exists, which can give birth to a child with signs of depression of vital activity in a short time after the treatment. In order to avoid this, it is necessary to carefully evaluate the condition of labor before the prescription of drug therapy. If this does happen, the pediatrician should be warned before delivery so that he can be prepared to begin the appropriate treatment for a newborn if necessary.

The second problem is the administration of small doses of drugs, which often prove ineffective and worsen the course of the existing complication. The recommended doses are adequate for most women and can be reduced only in parturients of small height and with low body weight. In parturients of greater weight, the dose of morphine can reach 20 mg subcutaneously. If after 20 minutes after the introduction of morphine contractile activity of the uterus is observed, it is necessary to additionally introduce another 10 mg, with an excessive mass of the mother giving - 15 mg of morphine.

When deciding to begin stimulation of labor with oxytocin, its intravenous drip introduction is used; while generic activities should be monitored. If the birth activity has already begun, then for its transition into the active phase, large doses of the drug may not be required. The introduction of oxytocin should begin with. 0.5-1.0 mU / min, gradually increasing the dose with 20-30-minute intervals. In most parturients with a latent phase of childbirth, the effect is observed with doses of oxytocin not exceeding 8 mU / min. It is recommended to dilute 10 units of oxytocin in 1000 ml of a 5% solution of dextrose. The introduction should be done with the help of a special perfusion, increasing gradually the dose every 20 minutes until the development of adequate labor.

A therapeutic error that should be avoided in the case of a protracted latency phase is the opening of the fetal bladder in order to accelerate the labor. According to Friedman (1978), amniotomy in this case is not successful.

In addition, since the prognosis for a prolonged latent phase is quite favorable and the treatment of this disorder usually ends up hastily, conducting caesarean section in such cases is not justified unless there are other indications other than an anomaly of labor. Common sense in conducting a caesarean section operation with a protracted latent phase is absent.

[1], [2], [3]