Prolonged active labor phase

A prolonged active phase of labor is characterized by a slow dilation of the cervix. The rate of dilation is less than 1.2 cm/h in primiparous women and less than 1.5 cm/h in women who have given birth to many children.

Diagnostics. To diagnose a protracted active phase, the following conditions must be met.

1. The woman in labor must be in the active phase of labor. Sometimes, during the latent phase/labor with cervical dilation of 3-4 cm, a diagnosis of a prolonged active phase may be erroneously made, when the rise of the curve characterizing the beginning of the active phase of labor has not yet been registered.
2. The labor process in the woman in labor should not yet have reached the deceleration phase. Sometimes a prolonged deceleration phase (a disorder caused by a stop) is confused with a prolonged active phase (a disorder associated with an increase in duration). This is especially often observed in combined anomalies of labor (for example, a prolonged active phase and a prolonged deceleration phase). However, such confusion will not occur if you carefully evaluate the indicators of the curve characterizing the labor process. At the same time, a disorder associated with an increase in duration is characterized by a slow opening of the cervix, leading to a change in the entire duration of the active phase.
3. The woman in labor should have at least two vaginal examinations performed with a 1-hour interval. However, a more accurate diagnosis can be made if the degree of cervical dilation is determined based on a partogram constructed taking into account the data of 3 or 4 vaginal examinations performed over a 3-4-hour period.

Frequency. A prolonged active phase is observed in approximately 2-4% of cases of labor. In more than 70%, this anomaly occurs in combination with cessation of labor or a prolonged latent phase.

Causes. The most common etiologic factors are excessive use of sedatives, conduction anesthesia, abnormal presentation of the fetus, and disproportion between the size of the fetus and the mother's pelvis. Disproportion occurs in 28.1% of cases. In 70.6% of cases, a transverse position of the sagittal suture or presentation of the fetus with the occiput facing backwards is detected.

Prognosis. Almost 70% of women in labor with a prolonged active phase develop one of the disorders associated with the cessation of cervical dilation or the cessation of the descent of the presenting part of the fetus. In the remaining women, labor continues at a slow pace, the prognosis for both the mother and the fetus is quite favorable in the absence of birth injuries.

The prognosis for women in labor who, after a prolonged active phase, develop disorders due to cessation of cervical dilation or fetal descent is quite unfavorable. 42% of them require delivery by caesarean section, 20% by application of obstetric forceps. The prognosis largely depends on the appearance of a certain rise on the curve, characterizing the dilation of the cervix. In addition, combined disorders are associated with a poor prognosis if they are detected before the cervix dilates by 6 cm. Another important factor in the prognosis of labor is their number: in the majority of multiparous women (83.3%) with combined labor disorders (slowing and stopping), treatment is effective and the cervix dilates later. Only 24% of them require a caesarean section.

Management of a prolonged active phase

Treatment of women with a prolonged active phase depends on the underlying cause. Since a discrepancy between the sizes of the fetus and the mother's pelvis is quite common, its presence should be suspected and a clinical assessment of this ratio should be made before starting therapeutic measures.

If it is desired to determine whether the head will pass through the pelvis, an attempt is made from time to time at the end of pregnancy to apply the Müller head compression. For this purpose, the head is pressed strongly into the pelvic inlet with the outer hand, and with the inner hand it is determined whether it is able to enter the pelvic inlet (in American literature, this technique is described as Hillis-Miiller). When establishing normal dimensions, the role of possible excessive use of sedatives or anesthesia, as well as abnormal presentation of the fetus, should be discussed.

If the probable cause is excessive use of sedatives or anesthesia, one should wait until their effect wears off and, consequently, the factor that caused the suppression of labor activity is eliminated on its own. If a discrepancy is established (according to pelvimetry data), a cesarean section should be performed.

Often, with a prolonged active phase, it is not possible to identify the causative factor. The pelvic dimensions are normal, with Müller's maneuver, a clear descent of the presenting part of the fetus is noted, the position of the fetal head is normal and the influence of any factors inhibiting labor has not been established. In such cases, it is recommended to insert an intrauterine catheter to accurately determine the nature of labor and, if the uterine ejection forces are insufficient, careful stimulation with oxytocin is necessary.

In normal contractions, oxytocin, amniotomy, or therapeutic sleep will not be of any benefit; cervical dilation will continue at a slow rate until the end of labor.

If the prolonged active phase is part of combined anomalies of labor, the woman in labor should be managed in accordance with the standards developed for the treatment of the most significant combined complications.

Thus, if a woman in labor, along with a prolonged active phase, experiences a cessation of cervical dilation, the management of labor is determined by the tactics developed for secondary cessation of cervical dilation (the more serious of these two labor anomalies).

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