98 Obstetrics and Gynecology Board Review •••
❍ What percentage of patients treated with therapeutic rest for prolonged latent phase will progress to active
phase?
85%.
❍ List the risk factors for protraction and arrest disorders in the first stage of labor.
Advanced maternal age.
Diabetes.
Hypertension.
Oligohydramnios.
Previous perinatal death.
Premature rupture of the membranes.
Chorioamnionitis.
Macrosomia.
Epidural anesthesia.
Pelvic contractures.
Nonreassuring fetal heart rate pattern.
❍ List the risk factors for arrest in the second stage of labor.
Occiput posterior presentation.
Prolonged first stage of labor.
Epidural analgesia.
Nulliparity.
Short maternal stature.
Increased maternal body mass index.
Macrosomia.
High station at complete cervical dilation.
❍ Is amniotomy beneficial for the patient with prolonged latent phase?
Amniotomy can shorten the latent phase of labor if used with active management of labor protocols. One
meta-analysis found that it shortened the first stage by up to 39 minutes.
❍ Describe the effect of amniotomy (performed during the active phase) on labor duration, maternal fever,
cesarean delivery, and nonreassuring fetal heart rate patterns.
Labor duration: Reduction by 1 to 2 hours.
Maternal fever: Increased incidence.
Cesarean delivery: No effect.
Nonreassuring fetal heart rate patterns: No effect.
❍ According to Friedman’s original data, the lower limit (5th percentile) for rate of cervical dilation in the active
phase is?
1.2 cm per hour in nulliparas and 1.5 cm per hour in multiparas. The most recent research by Zhang suggests that
these limits may no longer be valid and that labor may be longer than these numbers indicate.