Fetal Assessment and Prematurity

Question 1

How does the fetus respond to stress physiologically?

Answer 1

Peripheral vasoconstriction

Hypertension

Baroreceptor-mediated reduction in heart rate

Question 2

What is the normal range for fetal heart rate?

Answer 2

110-160

Question 3

What is fetal bradycardia?

Answer 3

<110

Question 4

What is fetal tachycardia?

Answer 4

> 160

Question 5

What are fetal causes of fetal bradycardia?

Answer 5

Asphyxia
Acidosis

Question 6

What are maternal causes of fetal bradycardia?

Answer 6

Hypoxemia

Drugs that decrease uteroplacental perfusion

Question 7

What are fetal causes of fetal tachycardia?

Answer 7

Hypoxemia
Arrhythmias

Question 8

What are maternal causes of fetal tachycardia?

Answer 8

Fever
Chorioiamnionitis
Atropine
Ephedrine
Terbutaline

Question 9

What range of variability should a fetal heart rate have?

Answer 9

6-25 bpm (excluding acceleration and deceleration)

Question 10

What are factors that reduce variability?

Answer 10

CNS depressants
Hypoxemia
Fetal sleep
Acidosis
Anencephaly
Cardiac anomalies

Question 11

What is the pathophysiology of early decelerations?

Answer 11

Uterine contractions compress the head > vagal stimulation > drop in FHR by <20bpm below baseline

Question 12

What is the pathophysiology of late decelerations?

Answer 12

Decreased uteroplacental perfusion > FHR falls after peak of contraction then returns to baseline after contraction

Question 13

What physical conditions may result in late decelerations?

Answer 13

Maternal hypotension, hypovolemia, acidosis, preeclampsia

Question 14

How do late decelerations present on the monitor?

Answer 14

FHR gradually falls after peak of each contraction then returns to baseline after contraction

Question 15

What is the pathophysiology of variable decelerations?

Answer 15

Umbilical compression > baroreceptor mediated reduction in FHR

Question 16

How do variable decelerations present on the monitor?

Answer 16

Maintain variability during deceleration

Usually self-limiting

Fetal compromise prolongs FHR recovery time

Question 17

What type(s) of deceleration(s) require(s) urgent assessment of fetal status d/t risk for fetal hypoxemia?

Answer 17

Late decelerations
Variable decelerations

Question 18

What findings are consistent with Category 1 FHR assessment?

Answer 18

Strongly suggests normal acid- base status with not threat to fetal oxygenation:

Baseline HR between 110-160

Moderate variability

Accelerations absent or present

Early decelerations absent or present

No late or variable decelerations

Question 19

What findings are consistent with Category 2 FHR assessment?

Answer 19

Cannot predict a normal or abnormal acid-base status:

Bradycardia without the absence of baseline FHR variability

Tachycardia

Variable variability

Absent or minimal acceleration with fetal stimulation

Recurrent variable decelerations

Question 20

What findings are consistent with Category 3 FHR assessment?

Answer 20

Strongly suggests abnormal acid-base status with a significant threat to fetal oxygenation:

Bradycardia

Absent baseline variability

Recurrent late deceleration

Recurrent variable deceleration

Sinusoidal pattern

Question 21

How is prematurity defined?

Answer 21

Delivery before 37 weeks gestation or less than 259 days from last menstrual cycle.

Question 22

What are some risk factors for prematurity?

Answer 22

Multiple gestations

Premature rupture of the membranes