A 36-year-old woman, gravida 1 para 0, at 38 weeks gestation comes to the hospital due to increased leakage of fluid. She reports spontaneous rupture of membranes approximately 48 hours earlier, and contractions started 12 hours after rupture. She reports intermittent vaginal spotting and regular fetal movement. The patient was attempting a home birth but came to the hospital because her cervix has been 6 cm dilated for the past 5 hours. Temperature is 39.4 C (103 F), blood pressure is 120/80 mm Hg, and pulse is 108/min. Digital examination reveals the cervix to be 6 cm dilated and 70% effaced, with the fetal vertex at 0 station. The fetal heart tracing is shown in the exhibit. Which of the following is most likely responsible for the findings on this patient's fetal monitoring?

Question

A 36-year-old woman, gravida 1 para 0, at 38 weeks gestation comes to the hospital due to increased leakage of fluid.  She reports spontaneous rupture of membranes approximately 48 hours earlier, and contractions started 12 hours after rupture.  She reports intermittent vaginal spotting and regular fetal movement.  The patient was attempting a home birth but came to the hospital because her cervix has been 6 cm dilated for the past 5 hours.  Temperature is 39.4 C (103 F), blood pressure is 120/80 mm Hg, and pulse is 108/min.  Digital examination reveals the cervix to be 6 cm dilated and 70% effaced, with the fetal vertex at 0 station.  The fetal heart tracing is shown in the exhibit.  Which of the following is most likely responsible for the findings on this patient's fetal monitoring?

Quizplus · Accepted Answer

11ec25c8_da2e_5932_bc81_3ff2db474449_MD0003_00 This patient has a fetal heart tracing with moderate variability and fetal tachycardia, a sustained fetal baseline heart rate >160/min. Common causes of fetal tachycardia include maternal infection, poorly controlled maternal hyperthyroidism, medication use (eg, terbutaline), and abruptio placentae. This patient has an intraamniotic infection (chorioamnionitis) of the uterine decidua, placenta, amniotic fluid, membranes, and umbilical cord that results from migration of vaginal or enteric flora through the cervix into the uterine cavity. fetal heart tracing abruptio placentae In the setting of protracted or arrested labor (slow labor progression) and prolonged membrane rupture (>18 hours), maternal fever suggests intraamniotic infection as the etiology of the fetal tachycardia. Additional clinical features of intraamniotic infection include maternal leukocytosis, purulent amniotic fluid, maternal tachycardia, and uterine fundal tenderness. Broad-spectrum antibiotics are administered to reduce the risk of neonatal (eg, sepsis, encephalopathy) and maternal (eg, postpartum hemorrhage, endometritis) morbidity. (Choice A) Fetal anemia typically presents with a sinusoidal fetal heart tracing, a smooth, undulating waveform with no variability. This patient's tracing has moderate variability. sinusoidal fetal heart tracing (Choice B) Early decelerations are shallow decreases in the fetal heart rate that occur as a mirror image with the uterine contraction. They are likely an autonomic response to alterations in intracranial pressure caused by fetal head compression during contractions. This fetal tracing has no early decelerations. Early decelerations (Choice C) Fetal sleep cycles are commonly associated with nonreactive non-stress tests (no accelerations), but they do not cause fetal tachycardia. (Choice E) Placental insufficiency causes late decelerations, which are smooth and subtle drops in the fetal heart rate following a contraction due to placental hypoperfusion during the contraction that results in transient fetal hypoxia. This fetal tracing has no late decelerations. (Choice F) Variable decelerations, abrupt drops in the fetal heart rate of varying depth and duration, are likely due to compression of the umbilical cord causing transient fetal hypertension that triggers a parasympathetic response and slows the heart rate. Umbilical cord compression does not cause sustained fetal tachycardia. Variable decelerations Educational objective: Intraamniotic infection, also known as chorioamnionitis, is a cause of fetal tachycardia (baseline heart rate >160/min). Intraamniotic infection is caused by migration of vaginal or enteric flora through the cervix and is associated with prolonged rupture of membranes and a protracted labor course. References: The 2008 national institute of child health and human development workshop report on electronic fetal monitoring: update on definitions, interpretation, and research guidelines. (http://www.ncbi.nlm.nih.gov/pubmed/18757666)

A 36-Year-Old Woman, Gravida 1 Para 0, at 38 Weeks