Acog trial of labor

Reference: Practice Bulletin No. American College of Obstetricians and Gynecologists. The type of scar depends on the type of cut in the uterus: Low transverse—A side-to-side cut made across the lower, thinner part of the uterus.

This is the most common type of incision and carries the least chance of future rupture. Low vertical—An up-and-down cut made in the lower, thinner part of the uterus. This type of incision carries a higher risk of rupture than a low transverse incision. This is sometimes done for very preterm cesarean deliveries. It has the highest risk of rupture.

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Find an Ob-Gyn Search for doctors near you. Start Your Search. The most common indications for primary cesarean delivery include, in order of frequency, labor dystocia, abnormal or indeterminate formerly, nonreassuring fetal heart rate tracing, fetal malpresentation, multiple gestation, and suspected fetal macrosomia.

Safe reduction of the rate of primary cesarean deliveries will require different approaches for each of these, as well as other, indications. For example, it may be necessary to revisit the definition of labor dystocia because recent data show that contemporary labor progresses at a rate substantially slower than what was historically taught. Additionally, improved and standardized fetal heart rate interpretation and management may have an effect.

External cephalic version for breech presentation and a trial of labor for women with twin gestations when the first twin is in cephalic presentation are other of several examples of interventions that can contribute to the safe lowering of the primary cesarean delivery rate.

In , one in three women who gave birth in the United States did so by cesarean delivery 1. Even though the rates of primary and total cesarean delivery have plateaued recently, there was a rapid increase in cesarean rates from to Figure 1. Although cesarean delivery can be life-saving for the fetus, the mother, or both in certain cases, the rapid increase in the rate of cesarean births without evidence of concomitant decreases in maternal or neonatal morbidity or mortality raises significant concern that cesarean delivery is overused 2.

Therefore, it is important for health care providers to understand the short-term and long-term tradeoffs between cesarean and vaginal delivery, as well as the safe and appropriate opportunities to prevent overuse of cesarean delivery, particularly primary cesarean delivery. Childbirth by its very nature carries potential risks for the woman and her baby, regardless of the route of delivery.

The National Institutes of Health has commissioned evidence-based reports over recent years to examine the risks and benefits of cesarean and vaginal delivery 3 Table 1. For certain clinical conditions—such as placenta previa or uterine rupture—cesarean delivery is firmly established as the safest route of delivery. However, for most pregnancies, which are low-risk, cesarean delivery appears to pose greater risk of maternal morbidity and mortality than vaginal delivery 4 Table 1.

It is difficult to isolate the morbidity caused specifically by route of delivery. For example, in one of the few randomized trials of approach to delivery, women with a breech presentation were randomized to undergo planned cesarean delivery or planned vaginal delivery, although there was crossover in both treatment arms 5. In this study, at 3-month follow-up, women were more likely to have urinary, but not fecal, incontinence if they had been randomized to the planned vaginal delivery group.

However, this difference was no longer significant at 2-year follow-up 6. Because of the size of this randomized trial, it was not powered to look at other measures of maternal morbidity. A large population-based study from Canada found that the risk of severe maternal morbidities —defined as hemorrhage that requires hysterectomy or transfusion, uterine rupture, anesthetic complications, shock, cardiac arrest, acute renal failure, assisted ventilation, venous thromboembolism, major infection, or in hospital wound disruption or hematoma—was increased threefold for cesarean delivery as compared with vaginal delivery 2.

There also are concerns regarding the long-term risks associated with cesarean delivery, particularly those associated with subsequent pregnancies. This combination of complications not only significantly increases maternal morbidity but also increases the risk of adverse neonatal outcomes, such as neonatal intensive care unit admission and perinatal death 3 9 Thus, although the initial cesarean delivery is associated with some increases in morbidity and mortality, the downstream effects are even greater because of the risks from repeat cesareans in future pregnancies Variation in the rates of nulliparous term singleton vertex cesarean births indicates that clinical practice patterns affect the number of cesarean births performed.

There also is substantial hospital-level variation. Studies have shown a fold variation in the cesarean delivery rate across hospitals in the United States, from 7. Studies that have evaluated the role of maternal characteristics, such as age, weight, and ethnicity, have consistently found these factors do not account fully for the temporal increase in the cesarean delivery rate or its regional variations 13 14 These findings suggest that other potentially modifiable factors, such as patient preferences and practice variation among hospitals, systems, and health care providers, likely contribute to the escalating cesarean delivery rates.

In order to understand the degree to which cesarean deliveries may be preventable, it is important to know why cesareans are performed. In a population-based study, the most common indications for primary cesarean delivery included, in order of frequency, labor dystocia, abnormal or indeterminate formerly, nonreassuring fetal heart rate tracing, fetal malpresentation, multiple gestation, and suspected fetal macrosomia Figure 3 Arrest of labor and abnormal or indeterminate fetal heart rate tracing accounted for more than one half of all primary cesarean deliveries in the study population.

Safe reduction of the rate of primary cesarean deliveries will require different approaches for each of these indications. For example, it may be necessary to revisit the definition of labor dystocia because recent data show that contemporary labor progresses at a rate substantially slower than what has been historically taught. Improved and standardized fetal heart rate interpretation and management also may have an effect.

External cephalic version for breech presentation and a trial of labor for women with twin gestations when the first twin is in cephalic presentation also can contribute to the safe lowering of the primary cesarean delivery rate. The first stage of labor has been historically divided into the latent phase and the active phase based on the work by Friedman in the s and beyond.

The latent phase of labor is defined as beginning with maternal perception of regular contractions On the basis of the 95th percentile threshold, historically, the latent phase has been defined as prolonged when it exceeds 20 hours in nulliparous women and 14 hours in multiparous women The active phase of labor has been defined as the point at which the rate of change of cervical dilation significantly increases.

Active phase labor abnormalities can be categorized either as protraction disorders slower progress than normal or arrest disorders complete cessation of progress. Active phase arrest traditionally has been defined as the absence of cervical change for 2 hours or more in the presence of adequate uterine contractions and cervical dilation of at least 4 cm. However, more recent data from the Consortium on Safe Labor have been used to revise the definition of contemporary normal labor progress In this retrospective study conducted at 19 U.

The Consortium on Safe Labor data highlight two important features of contemporary labor progress Figure 4. First, from 4—6 cm, nulliparous and multiparous women dilated at essentially the same rate, and more slowly than historically described. Beyond 6 cm, multiparous women dilated more rapidly.

Second, the maximal slope in the rate of change of cervical dilation over time ie, the active phase often did not start until at least 6 cm. The Consortium on Safe Labor data do not directly address an optimal duration for the diagnosis of active phase protraction or labor arrest, but do suggest that neither should be diagnosed before 6 cm of dilation.

Because they are contemporary and robust, it seems that the Consortium on Safe Labor data, rather than the standards proposed by Friedman, should inform evidence-based labor management. Although labor management strategies predicated on the recent Consortium on Safe Labor information have not been assessed yet, some insight into how management of abnormal first-stage labor might be optimized can be deduced from prior studies.

The definitions of a prolonged latent phase are still based on data from Friedman and modern investigators have not particularly focused on the latent phase of labor.

Most women with a prolonged latent phase ultimately will enter the active phase with expectant management. With few exceptions, the remainder either will cease contracting or, with amniotomy or oxytocin or both , achieve the active phase Thus, a prolonged latent phase eg, greater than 20 hours in nulliparous women and greater than 14 hours in multiparous women should not be an indication for cesarean delivery Table 3. When the first stage of labor is protracted or arrested, oxytocin is commonly recommended.

Several studies have evaluated the optimal duration of oxytocin augmentation in the face of labor protraction or arrest. A prospective study of the progress of labor in nulliparous women and 99 multiparous women who spontaneously entered labor evaluated the benefit of prolonging oxytocin augmentation for an additional 4 hours for a total of 8 hours in patients who were dilated at least 3 cm and had unsatisfactory progress either protraction or arrest after an initial 4-hour augmentation period Thus, slow but progressive labor in the first stage of labor should not be an indication for cesarean delivery Table 3.

A study of more than women found that extending the minimum period of oxytocin augmentation for active phase arrest from 2 hours to at least 4 hours allowed the majority of women who had not progressed at the 2-hour mark to give birth vaginally without adversely affecting neonatal outcome The researchers defined active phase labor arrest as 1 cm or less of labor progress over 2 hours in women who entered labor spontaneously and were at least 4 cm dilated at the time arrest was diagnosed.

Subsequently, the researchers validated these results in a different cohort of prospectively managed women An additional study of 1, women conducted by different authors demonstrated that using the same criteria in women with spontaneous labor or induced labor would lead to a significantly higher proportion of women achieving vaginal delivery with no increase in neonatal complications Of note, prolonged first stage of labor has been associated with an increased risk of chorioamnionitis in the studies listed, but whether this relationship is causal is unclear ie, evolving chorioamnionitis may predispose to longer labors.

Thus, although this relationship needs further elucidation, neither chorioamnionitis nor its duration should be an indication for cesarean delivery Given these data, as long as fetal and maternal status are reassuring, cervical dilation of 6 cm should be considered the threshold for the active phase of most women in labor Box 1.

Thus, before 6 cm of dilation is achieved, standards of active phase progress should not be applied Table 3. Further, cesarean delivery for active phase arrest in the first stage of labor should be reserved for women at or beyond 6 cm of dilation with ruptured membranes who fail to progress despite 4 hours of adequate uterine activity, or at least 6 hours of oxytocin administration with inadequate uterine activity and no cervical change Table 3 Spontaneous labor: More than or equal to 6 cm dilation with membrane rupture and one of the following:.

The second stage of labor begins when the cervix becomes fully dilated and ends with delivery of the neonate. Parity, delayed pushing, use of epidural analgesia, maternal body mass index, birth weight, occiput posterior position, and fetal station at complete dilation all have been shown to affect the length of the second stage of labor Further, it is important to consider not just the mean or median duration of the second stage of labor but also the 95th percentile duration.

This method provides women who desire a vaginal delivery the possibility of achieving that goal—a vaginal birth after cesarean delivery VBAC. However, although TOLAC is appropriate for many women, several factors increase the likelihood of a failed trial of labor, which in turn is associated with increased maternal and perinatal morbidity when compared with a successful trial of labor ie, VBAC and elective repeat cesarean delivery 4 5 6. Thus, the purpose of this document is to review the risks and benefits of TOLAC in various clinical situations and to provide practical guidelines for counseling and management of patients who will attempt to give birth vaginally after a previous cesarean delivery.

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