Approach To Fetal Bradycardia Definitions

Engagement: Largest transverse (biparietal) diameter of the fetal head has negotiated the bony pelvic inlet.

Fetal Bradycardia: Baseline fetal heart less than 110 bpm for more than 10 min.

Umbilical cord prolapse: Umbilical cord enters through the cervical os appears in front of the presenting part.

Artificial rupture of membranes: Maneuver used to cause a rent in the fetal chorioamniotic membranes.

Clinical Approach

The onset of fetal bradycardia should be confirmed by either internal fetal scalp electrode or ultrasound and distinguished from the maternal pulse. The initial steps should be directed at improving maternal oxygenation and delivery of cardiac output to the uterus. These maneuvers include 1) placement of the patient on her side to move the uterus from the great vessels, thus improving blood return to the heart: 2) intravenous fluid bolus if the patient is possibly volume depleted; 3) administration of 100% oxygen by face mask; and 4) stopping oxytocin if it is being given (Table 18-1).

Simultaneously with these maneuvers, the practitioner should try to identify the cause of the bradycardia, such as hyperstimulation with oxytocin. With this process, the uterus will be tetanic, or the uterine contractions will be frequent (every I min); often a (i-agonist, such as terbutaline, given intravenously will help relax the uterine musculature. Hypotension due to an epidural catheter is another common cause. Intravenous hydration is the first remedy: if unsuccessful, then support of the blood pressure with ephedrine. a pressor agent, often is useful. Vaginal examination when the membranes are ruptured is a "must" to identify overt umbilical cord prolapse. A ropelike cord will be palpated, often with pulsations (Figure 18-1). The best treatment is elevation of the presenting part digitally and emergent cesarean delivery. In women with prior cesarean delivery, uterine rupture may manifest as fetal bradycardia.

Table 18-1

STEPS TO TAKE WITH FETAL BRADYCARDIA

Confirm fetal heart rate (versus maternal heart rate) Vaginal examination to assess for cord prolapse Positional changes Oxygen

Intravenous fluid bolus Discontinue oxytocin

Fetal Bradycardia During Labor
predisposes to umbilical cord prolapse.

Comprehension Questions

[18.1] An 18-year-old woman who had undergone a previous low-transverse cesarean delivery is admitted for active labor. During labor, an intrauterine pressure catheter displays normal uterine contractions every 3 min with intensity up to 60 mm Hg. Fetal bradycardia ensues. Which of the following statements is most accurate?

A. The normal intrauterine pressure catheter display makes uterine rupture unlikely.

B. The most common sign of uterine rupture is a fetal heart rate abnormality.

C. If the patient has a uterine rupture, the practitioner should wait to see whether the heart tones return to decide on route of delivery.

D. The intrauterine pressure catheter has been found to be helpful in preventing uterine rupture.

[18.2] Umbilical cord prolapse is most likely with which of the following?

A. Transverse lie

B. Face presentation

C. Frank breech presentation

D. Complete breech presentation

E. Oblique lie

[18.3] Which of the following maneuvers improves oxygenation to the placenta?

A. Lateral position

B. Epidural anesthesia

C. Morphine sulfate

D. Intravenous oxytocin

118.4] A 33-year-old G2 PI woman at 39 weeks' gestation in active labor is noted to have a 1-min episode of bradycardia in the I(X)-bpm range on the external fetal heart rate tracing, which has not resolved. Her cervix is closed. Which of the following is the best initial step in management of this patient?

A. Fetal scalp pH assessment

B. Emergency cesarean delivery

C. Intravenous atropine

D. Intravenous terbutaline

E. Assess maternal pulse

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