A 28-year-old woman, gravida 2 para 1, at 38 weeks gestation is admitted to labor and delivery due to prelabor rupture of membranes. Clear amniotic fluid has been leaking continuously for the last 2 hours. The patient has irregular, nonpainful contractions and no vaginal bleeding. Prenatal care during this pregnancy has been uncomplicated, and the patient's previous pregnancy ended in a term vaginal delivery. Temperature is 36.7 C (98.1 F), blood pressure is 120/70 mm Hg, and pulse is 78/min. The cervix is 3 cm dilated and 50% effaced with the fetal vertex at ?2 station. Fetal heart tracing on admission is as seen in the exhibit. After an oxytocin infusion is started for labor augmentation, the patient begins to have regular, painful contractions that require epidural anesthesia. Two hours later, temperature is 37.2 C (99 F), blood pressure is 120/80 mm Hg, and pulse is 80/min. On repeat examination the cervix is now 7 cm dilated, 100% effaced, with the fetal vertex at +1 station; and current fetal heart tracing is as seen in the exhibit. Which of the following is the best next step in management of this patient?

Question

A 28-year-old woman, gravida 2 para 1, at 38 weeks gestation is admitted to labor and delivery due to prelabor rupture of membranes.  Clear amniotic fluid has been leaking continuously for the last 2 hours.  The patient has irregular, nonpainful contractions and no vaginal bleeding.  Prenatal care during this pregnancy has been uncomplicated, and the patient's previous pregnancy ended in a term vaginal delivery.  Temperature is 36.7 C (98.1 F), blood pressure is 120/70 mm Hg, and pulse is 78/min.  The cervix is 3 cm dilated and 50% effaced with the fetal vertex at ?2 station.  Fetal heart tracing on admission is as seen in the exhibit.  After an oxytocin infusion is started for labor augmentation, the patient begins to have regular, painful contractions that require epidural anesthesia.  Two hours later, temperature is 37.2 C (99 F), blood pressure is 120/80 mm Hg, and pulse is 80/min.  On repeat examination the cervix is now 7 cm dilated, 100% effaced, with the fetal vertex at +1 station; and current fetal heart tracing is as seen in the exhibit.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

This patient's fetal heart rate tracing has recurrent late decelerations (ie, late decelerations in ?50% of contractions). Late fetal decelerations are a sign of uteroplacental insufficiency and impending fetal hypoxemia and acidemia. This patient's fetal decelerations are most likely due to uterine tachysystole, defined as >5 contractions/10 min. Uterine contractions temporarily interrupt intervillous blood flow; excessively frequent contractions, as in this patient, may cause fetal compromise as a result of decreased uteroplacental blood flow during contractions and inadequate recovery time (resumption of blood flow) between contractions. Although uterine tachysystole can occur in spontaneous labor, there is an increased risk with induced or augmented labor (eg, uterotonic agents). Uterine tachysystole is managed with supportive measures (eg, lateral maternal repositioning, tocolysis) and discontinuation of uterotonic agents (eg, oxytocin) until the excessive uterine activity and resulting fetal decelerations resolve (Choice B). uterine tachysystole (Choice A) Broad-spectrum antibiotics are administered in the setting of intrauterine infection (chorioamnionitis), which causes maternal fever and fetal tachycardia (baseline >160/min); intrauterine infection is not seen in this patient. (Choice C) Epidural anesthesia may cause maternal hypotension, with resulting fetal decelerations and loss of variability. However, decreasing the epidural infusion rate would not resolve this patient's tachysystole. In addition, this patient is normotensive. (Choice E) Amnioinfusion increases intrauterine fluid volume and is initiated to improve variable fetal decelerations caused by cord compression (eg, oligohydramnios) in labor. It is not indicated for late fetal decelerations or tachysystole. Educational objective: Uterine tachysystole, or >5 contractions/10 min, may cause fetal compromise (eg, hypoxemia, acidemia) due to interruption of intervillous blood flow and inadequate recovery time between contractions (eg, late decelerations). Management is with supportive measures and discontinuation of uterotonic agents (eg, oxytocin). References: Tachysystole following cervical ripening and induction of labor is not associated with adverse outcomes. (http://www.ncbi.nlm.nih.gov/pubmed/27816973) Acute tocolysis for uterine tachysystole or suspected fetal distress. (http://www.ncbi.nlm.nih.gov/pubmed/29971813) Discontinuing oxytocin infusion in the active phase of labor: a systematic review and meta-analysis. (http://www.ncbi.nlm.nih.gov/pubmed/29016497) Uterine tachysystole in spontaneous labor at term. (http://www.ncbi.nlm.nih.gov/pubmed/27074823)

A 28-Year-Old Woman, Gravida 2 Para 1, at 38 Weeks