A 32-year-old woman, gravida 2 para 1, at 40 weeks gestation is admitted to the hospital due to spontaneous rupture of membranes and regular, painful contractions. This pregnancy has been uncomplicated, but her last pregnancy resulted in an operative vaginal delivery for a non-reassuring fetal status. The patient has no chronic medical conditions and no prior surgeries. Her digital cervical examinations since admission are shown below:
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Current temperature is 37.2 C (99 F), blood pressure is 120/70 mm Hg, and pulse is 68/min. Fetal heart rate monitoring is category I and tocodynamometer shows contractions every 2-3 minutes. Which of the following is the best next step in management of this patient?
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The first stage of labor begins with the onset of regular contractions and lasts until complete (10 cm) cervical dilation. The first stage is divided into phases:
the latent phase (0-6 cm), when the cervix dilates slowly and has no defined expected rate of cervical change
the active phase (≥6-10 cm), when the cervix dilates rapidly with a normal progression of ≥1 cm every 2 hours
When evaluating this patient's labor curve, note that her latent phase had a rate of 3 cm in 6 hours (ie, it took 6 hours to dilate from 3 to 6 cm). After entering the active phase (≥6 cm), the patient's cervix has dilated 1 cm/hr (ie, it took 2 hours to dilate from 6 to 8 cm), consistent with normal labor progression. The associated fetal station seen on the labor curve (from −2 to +1 station) is consistent with normal progression but does not affect management. Because this patient has normal labor progression, stable vital signs, and a category I fetal heart rate tracing (ie, reassuring status), she can continue expectant management.
(Choice A) Cesarean delivery is indicated for active phase labor arrest (defined as no cervical change for ≥4 hours with adequate contractions or ≥6 hours with inadequate contractions) or a category III fetal heart rate tracing.
(Choices C and E) When labor has not completely arrested but cervical change slows to <1 cm/2 hr (labor protraction), an intrauterine pressure catheter is placed to measure contraction frequency and force (via Montevideo units). If contractions are inadequate (<200 Montevideo units), labor is augmented with oxytocin in order to increase contraction frequency and force.
(Choice D) An operative vaginal delivery (eg, forceps-assisted vaginal delivery) is performed to expedite delivery for category III tracings or maternal exhaustion during the second stage of labor (10 cm dilation until fetal delivery). This patient is 8 cm dilated.
Educational objective:
The first stage of labor is divided into 2 phases: the latent phase (0-6 cm) and the active phase (≥6-10 cm). Normal labor progression in the active phase is ≥1 cm every 2 hours. Patients with normal labor progression and reassuring maternal-fetal status are managed expectantly.