Management of labor includes several components, including a strict and disciplined approach to the diagnosis of labor, regular assessment of maternal and fetal well-being, and careful monitoring of labor progress. Once labor dystocia is recognized and confirmed, management depends on the etiology and stage or phase of labor. Appropriate and timely intervention with oxytocin augmentation may reduce maternal and neonatal morbidity.
Good prenatal care and preparation for childbirth reduce the incidence of prolonged labor. Continuous close support during labor has also been shown to prevent the incidence of labor dystocia
Labor should not be induced in the absence of a medical indication for induction and/or when the cervix is not favorable
The patient’s general physical and mental condition is assessed with respect to fatigue, morale, hydration, and nourishment
False labor is treated by adequate rest, hydration, and support. Judicious use of appropriate analgesia in the early phase of labor should also be given
Admission to the birthing unit should be delayed until the woman has entered the active phase of labor as long as maternal and fetal well-being are confirmed
Avoid routine amniotomy, especially in the latent phase of labor
Avoid a diagnosis of labor dystocia in the latent phase of labor. Newer studies suggest cervical dilation of 6 cm to be considered the threshold for active phase of most women in labor
Assess adequacy of labor progress. By charting the progress of labor on a partogram (see Fig. 14-1), we can ascertain whether cervical dilatation is occurring at a normal rate, too slowly, or has ceased altogether. The type of abnormality can be diagnosed, and the point at which intervention is necessary is indicated
Once labor dystocia is diagnosed and confirmed (Table 14-2), vaginal examination should be performed at 2-hour intervals in the first stage and 1-hour intervals in the second stage of labor to ensure adequate progress in labor. A careful assessment of the cervix and fetal station and position is performed.
TABLE 14-2:LABOR DYSTOCIA CHECKLIST ||Download (.pdf) TABLE 14-2: LABOR DYSTOCIA CHECKLIST
1. Diagnosis of Dystocia/Arrest Disorder (all three should be present)
Cervix 6 cm or greater
Membranes ruptured, then
No cervical change after at least 4 hours of adequate uterine activity (e.g., strong to palpation or Montevideo units >200), or at least 6 hours of oxytocin administration with inadequate uterine activity
2. Diagnosis of Second Stage Arrest (only one needed)
No descent or rotation for:
at least 4 hours of pushing in nulliparous woman with epidural
at least 3 hours of pushing in nulliparous woman without epidural
at least 3 hours of pushing in multiparous woman with epidural
at least 2 hour of pushing in multiparous woman without epidural
3. Diagnosis of Failed Induction (both needed)
Bishop score ≥6 for multiparous women and ≥8 for nulliparous women, before the start of induction (for nonmedically indicated/elective induction of labor only)
Oxytocin administered for at least 12-18 hours after membrane rupture, without achieving cervical change and regular contractions. *note: at least 24 hours of oxytocin administration after membrane rupture is preferable if maternal and fetal statuses permit
Has there been any progress or further dilatation since the last examination? Is the cervix swollen suggestive of obstructed labor? Is an anterior cervical lip caught between the head and the symphysis?
Station of Presenting Part
The station of the bony presenting part is determined. Is it at, above, or below the spines? Has engagement taken place? Is there a caput? Is molding excessive?
The position must be diagnosed accurately. In all cases of prolonged labor, malpositions such as brow presentation and occiput posterior should be kept in mind.
What seems to be holding up the presenting part? Is the cause of arrest in the bony pelvis or the cervix? Is the head too big for the pelvis? Or is the problem not the pelvis, the cervix, or the fetus, but in the uterine contractions, and will a few hours of really good labor achieve progress to successful delivery?
The uterine contractions are assessed in terms of strength and frequency. Is the basic problem in the type of labor, or is the main problem elsewhere and the poor uterine action a secondary complication? If the contractions are judged to be efficient, then the reason for the failure of progress must be in another field. Because inefficient uterine action is almost entirely a disorder of primigravidas, multiparas with prolonged labors must be investigated for other factors carefully before a diagnosis of poor labor is made. A woman who has delivered a 7-pound baby with no trouble may not be able to do the same with a 9-pound baby.
The strength of the contractions may be assessed manually or with the use of an electronic external or internal uterine pressure monitoring system.
Dystocia in the First Stage
Mechanical factors must be ruled out. In some cases, there is cephalopelvic disproportion, and cesarean section is indicated. For the rest, hypotonic uterine contractions account for the majority of slowly progressive labor, and medical management is carried out as long as the fetus and mother are in good condition. Nothing is done to complicate the situation further. Slow progress is accepted. Support, reassurance, rest, fluids, and analgesia are provided. Premature and traumatic vaginal operations are not recommended.
Therapeutic rest involves providing pain relief by effective support and analgesia. Some women who experience excessive pain or anxiety during labor produce high endogenous catecholamines, which has a direct inhibitory effect on uterine contractions. This leads to a vicious cycle of inefficient uterine contractions, poor labor progress, increased anxiety, and higher catecholamines. Nonpharmacologic and pharmacologic options for pain management should be provided.
Parenteral narcotics with a short half-life are effective in providing short-term pain relief. Epidural anesthesia has an advantage of providing effective pain relief for the duration of labor and allows women to rest (see Chapter 36). In particular, it allows the administration of oxytocin augmentation for women with labor dystocia without increasing the amount of labor pain significantly.
Epidural anesthesia is associated with prolonged labor in the first and second stages of labor, an increased incidence of fetal malposition, an increased use of oxytocin augmentation, and an increased risk of assisted vaginal deliveries. It has not been shown to increase the risk of cesarean section, although studies are conflicting.
Amniotomy alone when used in the latent phase of labor is usually insufficient to result in significant augmentation of labor. Routine and early amniotomy has also not been shown to accelerate spontaneous labor or increase the chance of a successful vaginal delivery. However, in the setting of prolonged or delayed labor in the active phase, amniotomy is recommended in all women with intact membranes. Performing an amniotomy increases local prostaglandin levels and may increase the strength and frequency of uterine contractions. Amniotomy in this setting has also been shown to shorten the duration of the first stage of labor.
When all other more conservative measures have been attempted to stimulate more effective contractions and in the setting of stable maternal and fetal conditions, it is recommended that labor augmentation be started with oxytocin before a caesarean delivery being performed for “failure to progress.” Oxytocin should be initiated in cases of labor dystocia caused by inadequate of inefficient uterine contractions. Oxytocin, when administered intravenously as a constant infusion, increases the frequency, force, and duration of uterine contractions. Several studies have shown that oxytocin augmentation decreases the duration of labor and increases the rate of successful spontaneous vaginal delivery.
It should be used with caution when cephalopelvic disproportion is suspected, in cases of hypersensitivity to oxytocin, uteroplacental insufficiency, abnormal fetal heart rate (FHR), and previous cesarean section.
When oxytocin is used, an initial dose of 1-2 mU/min of oxytocin is started. It should be titrated slowly to achieve a contraction pattern of four or five contractions in 10 minutes. This should be done gradually with a 30-minute interval between dose increases. While most patients achieve a response to stimulation at oxytocin concentrations between 4 and 10 mU/min, a proportion of nullipara require higher doses of oxytocin. When 20 mU/min of oxytocin is reached, a careful reevaluation of the labor progress and maternal and fetal well-being should be carried out before further increases in oxytocin titration. Continuous electronic fetal heart rate monitoring (EFM) should be implemented whenever oxytocin is used.
Oxytocin use is associated with an increased incidence of tachysystole. Tachysystole is defined as a contraction frequency of more than five contractions in 10 minutes with less than 60 seconds of resting tone or uterine contractions lasting for more than 2 minutes. It can occur with or without FHR abnormalities. Persistent uterine tachysystole with FHR abnormalities can lead to fetal hypoxia if not corrected. Appropriate use and titration of the oxytocin dose to achieve minimally effective strength and frequency of uterine contractions, without causing too much, is usually sufficient to correct tachysystole.
Uterine tachysystole is associated with (1) high-dose oxytocin titration regimens (4-6 mU/min oxytocin increments) and (2) when incremental increases in oxytocin dose are increased at intervals of less than 30 minutes.
Fetal Heart Rate Monitoring
Continuous FHR monitoring should be offered when labor dystocia is diagnosed. Whenever oxytocin is used, continuous external or internal FHR monitoring should be used (see Chapter 12).
The cervix may be holding up progress. A thick anterior lip or a thin, soft rim of cervix may be caught between the head and the symphysis pubis. This can be pushed over the head during a contraction, especially in multiparous women.
Arrest of Labor in the Second Stage
Clinical reassessment of labor progress should be done at hourly intervals in the second stage. It is vital that mechanical factors be ruled out carefully. These include malpositions and malpresentations as well as cephalopelvic disproportion. Cesarean section is performed in most cases of cephalopelvic disproportion.
Maternal and fetal well-being should be monitored carefully. Continuous EFM is recommended when there is a delay in the second stage to ensure that the fetus is tolerating labor. In the setting of good fetal well-being, support, rest, and adequate pain relief for the exhausted mother may be beneficial in the second stage. A passive second stage (or delayed pushing) allows for fetal descent to occur mainly from the action of the uterine contractions without exhausting the mother. Where membranes are still intact in the second stage, they should be artificially ruptured.
Oxytocin should be started as soon as labor dystocia is recognized in the second stage. The same principles for oxytocin use in the first stage of labor are applied in the second stage. It should be used with caution when cephalopelvic disproportion is suspected and in cases of hypersensitivity to oxytocin, uteroplacental insufficiency, abnormal FHR, and previous cesarean section.
If progress is being made and vaginal delivery is expected, the duration of the second stage alone should not mandate intervention with operative delivery.
Delivery by cesarean section or assisted vaginal delivery is indicated when there is no further progress despite oxytocin augmentation. In the first stage of labor, an adequate trial of oxytocin augmentation with a minimum of 4 hours of minimally effective uterine contractions should be given before operative delivery is considered. Minimally effective uterine contractions is defined either as uterine contractions achieving 200 or more Montevideo units or three or four strong contractions every 10 minutes. In spontaneously laboring women with slow progress of labor at term, oxytocin augmentation for 4 hours can result in vaginal deliveries in approximately 80 percent of nulliparous women and 95 percent of multiparous women with no adverse effect on the mother or baby. After an adequate trial of oxytocin augmentation and complete arrest of dilatation of the cervix occurs in the first stage of labor (dilatation arrests at less than 10 cm), vaginal delivery is impossible at this time, and cesarean section must be performed.
When arrest of labor in the second stage is established, operative delivery is indicated when there is no further descent of the presenting part after 1 hour of active pushing with adequate contractions. If the presenting part is low in the pelvis, there is no disproportion, and the baby may be delivered by forceps or vacuum if the presentation is cephalic and by cesarean section if he or she is a breech. The decision to proceed with an assisted vaginal delivery versus a cesarean section should be made on the basis of the clinical assessment of the mother and fetus and the skill of the obstetrician.
At any sign fetal or maternal distress, early intervention and operative delivery are indicated. Preparations should be at hand for the treatment of postpartum hemorrhage and fetal distress.