116 - Management of Intrapartum Fetal Heart Rate Tracings

Question 1

Normal uterine activity

Answer 1

5 or fever contractions in 10 minutes averaged over a 30 minute window

Question 2

Tachysystole

Answer 2

More than 5 contractions in 10 minutes averaged over 30 minutes. Should be categorized by the presence or absence of FHR decelerations.

Question 3

How often should a category I tracing be reviewed?

Answer 3

• q30 minutes during 1st stage

- q15 minutes during 2nd stage

Question 4

For a category II tracing, what features are highly predictive of normal fetal acid-base status?

Answer 4

• Accelerations

- Moderate variability

Question 5

Intermittent variable decelerations

Answer 5

• Occur with less than 50% of contractions

- Most common FHR abnormality during labor

Question 6

Recurrent variable decelerations

Answer 6

• Occur with greater than or equal to 50% of contractions

- Can progress to greater depth and longer duration are more indicative of impending fetal acidemia

Question 7

Management of recurrent variable decelerations should be directed at

Answer 7

Relieving umbilical cord compression:

• Initiate maternal repositioning
• Oxygenation
• Initiate amnioinfusion
• If prolapsed umbilical cord is noted, elevate the presenting fetal part while preparations are underway for operative delivery

Question 8

Recurrent late decelerations are thought to reflect

Answer 8

Transient or chronic uteroplacental insuffieciency

Question 9

Common causes of recurrent late decelerations

Answer 9

• Maternal hypotension (eg postepidural)
• Uterine tachysystole
• Maternal hypoxia

Question 10

Management of recurrent late decelerations

Answer 10

Involves maneuvers to promote uteroplacental perfusion:

• Initiate lateral positioning (left or right)
• Adminiter maternal oxygen administration
• Administer IV fluid bolus
• Reduce uterine contraction frequency (oxytocin)

Question 11

Fetal tachycardia

Answer 11

Baseline heart rate greater than 160 bpm for at least 10 minutes

Question 12

Causes of fetal tachycardia

Answer 12

• Infectiong (eg chorioamnionitis, pyelonephritis or other maternal infections)
• Medications (eg terbutaline, cocaine, or other stimulants)
• Maternal medical disorders (eg hyperthyroidism)
• Obstetric conditions (eg placental abruption or fetal bleeding)
• Fetal tachyarrhythmias (often associated with FHR greater than 200 bpm)

Question 13

In isolation, is fetal tachycardia predictive of fetal hypoxemia or acidemia?

Answer 13

No, unless accompanied by minimal or absent FHR variability or recurrent decelerations

Question 14

Fetal bradycardia

Answer 14

Baseline heart rate of less than 110 bpm for at least 10 minutes

Question 15

Prolonged decelerations

Answer 15

FHR decreases of at least 15 bpm below baseline that last at least 2 minutes but less than 10 minutes

Question 16

Common causes of fetal bradycardia

Answer 16

• Maternal hypotension (eg postepidural)
• Umbilical cord prolapse or occlusion
• Rapid fetal descent
• Tachysystole
• Placental abruption
• Uterine rupture
• Congenital heart abnormalities
• Myocardial conduction defects (such as those associated with maternal collagen vascular disease)

Question 17

Causes of minimal FHR variability

Answer 17

• Maternal medications (eg opioid, magnesium sulfate)
• Fetal sleep cycle
• Fetal acidemia

Question 18

How long does it take for minimal variability thought to be due to recent maternal opioid administration to return to normal?

Answer 18

FHR variability often improves and returns to moderate variability within 1-2 hours

Question 19

How long do fetal sleep cycles last?

Answer 19

20 minutes, but can persist up to 60 minutes

Question 20

Management of minimal FHR variability if thought to be due to decreased fetal oxygenation

Answer 20

• Initiate lateral positioning (either left or right)
• Administer maternal oxygen
• Adminiter IV fluid bolus
• Reduce uterine contraction frequency (oxytocin)

Question 21

If no improvement in FHR variability is seen with initial measures and there are no FHR accelerations, what additional assessments may be done?

Answer 21

Digital scalp or vibroacoustic stimulation

Question 22

For women with spontaneous labor, tachysystole coupled with recurrent FHR decelerations require what evaluation and treatment

Answer 22

• Category I: no interventions required

- Category II or III: intrauterine resuscitative measures and if no resolution, consider tocolytic

Question 23

For women in labor induction, tachysystole couple with recurrent FHR decelerations require what evaluation and treatment

Answer 23

• Category I: decrease uterotonics
• Category II or III: decrease or stop uterotonics, intrauterine resuscitative measures, and if still no resolution, consider a tocolytic

Question 24

Category III tracings have been associated with an increased risk for

Answer 24

• Neonatal encephalopathy
• Cerebral palsy
• Neonatal acidosis

Question 25

Potential logistical considerations in preparation for operative delivery in setting of category III tracing

Answer 25

- Obtain informed consent (verbal or written as feasible) - Assemble surgical team (surgeon, scrub tech, and anesthesia personnel) - Assess patient transient time and location for operative delivery - Ensure IV access - Review status of lab tests (blood type and screen) and assess need for availability of blood products - Assess need for preoperative placement of indwelling foley catheter - Assemble personnel for neonatal resuscitation

Question 26

Category I - baseline rate, FHR variability, presence of: late, variable or early decelerations and accelerations

Answer 26

- Baseline rate: 110-160 bpm - Baseline FHR variability: moderate - Late or variable decelerations: absent - Early decelerations: present or absent - Accelerations: present or absent

Question 27

Category II - baseline rate, FHR variability, presence of: late, variable or early decelerations and accelerations

Answer 27

Baseline rate: - Bradycardia not accompanied by absent baseline variability - Tachycardia Baseline FHR variability: - Minimal baseline variability - Absent baseline variability with no recurrent decelerations - Marked baseline variability Accelerations: - Absence of induced accelerations after fetal stimulation Periodic or episodic decelerations: - Recurrent variable decelerations accompanied by minimal or moderate baseline variability - Prolonged deceleration more than 2 minutes but less than 10 minutes - Recurrent late decelerations with moderate baseline variability - Variable decelerations with other characteristics such as slow return to baseline, overshoots or shoulders

Question 28

Category III - baseline rate, FHR variability, presence of: late, variable or early decelerations and accelerations

Answer 28

``` Absent baseline FHR variability and any of the following: - Recurrent late decelerations - Recurrent variable decelerations - Bradycardia Sinusoidal pattern ```