Labor Management: Guidelines From the American College of Obstetricians and Gynecologists

Nearly one-third of births in the United States are cesarean deliveries despite a greater risk of maternal morbidity and mortality compared with vaginal delivery. Labor dystocia is the most common indication for primary cesarean delivery. The American College of Obstetricians and Gynecologists released guidelines on managing the first and second phases of labor.

The onset of labor is when regular and painful uterine contractions result in cervical dilation or effacement. Determining when labor shifts from the latent stage to the active stage is important for defining when active labor arrest has occurred.

Latent Phase

The latent phase comprises regular and painful uterine contractions with cervical dilation of less than 6 cm. Its duration varies, regardless of parity. The latent phase is considered prolonged when it lasts more than 16 hours. There is no accepted definition of latent phase arrest, and cesarean delivery for latent phase arrest should be avoided.

Active Phase

The guidelines recommend that the active phase of labor be defined as beginning when the cervix is 6 cm dilated. This definition is based on a large retrospective study from 2010 of more than 62,000 cases that refined the previous definition.

Active Phase Protraction and Arrest

The guidelines recommend that active phase arrest be defined as the lack of further cervical dilation in patients with at least 6 cm of dilation and ruptured membranes despite 4 hours of adequate uterine contractions or 6 hours of oxytocin administration with inadequate uterine contractions; labor protraction is defined as progression of labor that is slower than normal. Adequate contractions are defined as having greater than 200 Montevideo units via intrauterine pressure catheter, although this threshold is based on one small observational study. Cesarean delivery is indicated after active phase arrest is diagnosed.

Active phase labor is considered protracted when less than 1 cm of dilation occurs in 2 hours. With additional augmentation, one-half of patients with a prolonged active phase will still deliver vaginally.

Second Stage

The second stage of labor starts at 10 cm of cervical dilation and ends with delivery of the infant. It is considered prolonged when the infant has not been delivered after more than 3 hours of pushing in a nulliparous patient or more than 2 hours of pushing in a multiparous patient. Identification of second stage arrest should focus on lack of fetal rotation or descent despite adequate contractions and maternal pushing efforts.

Second stage arrest can be managed with operative vaginal delivery or cesarean delivery. The guidelines suggest consideration of operative vaginal delivery to reduce maternal morbidity with similar neonatal morbidity. Fewer than 3% of patients with an attempted operative vaginal delivery proceed to have a cesarean delivery. Limited evidence suggests that ultrasonography before operative vaginal delivery does not improve outcomes and that it increases cesarean delivery rates.