Fetal Monitoring

Question 1

What is the purpose of electronic fetal monitoring (EFM)?

Answer 1

EFM measures the response of fetal heart rate (FHR) to uterine contractions during labor.

Question 2

What are the two main types of EFM?

Answer 2

1. External fetal monitoring (EFM)
2. Internal fetal monitoring (IFM)

Question 3

What are the components of internal fetal monitoring (IFM)?

Answer 3

1. Fetal scalp electrode: Monitors FHR.
2. Intrauterine pressure catheter: Measures uterine contractions.

Question 4

When is internal fetal monitoring typically used?

Answer 4

1. After membrane rupture.
2. Very morbid obesity.

Question 5

What is external fetal monitoring (EFM)?

Answer 5

A non-invasive method using external detectors to monitor:

FHR: Via an ultrasound transducer.

Uterine activity: Via a tocotransducer.

Question 6

What are the advantages of external fetal monitoring (EFM)?

Answer 6

It avoids the need for membrane rupture and uterine invasion.

Question 7

Where are the transducers placed in external fetal monitoring?

Answer 7

On the mother’s abdomen

Question 8

What is the normal baseline fetal heart rate (FHR)?

Answer 8

The normal baseline FHR ranges between 110-160 beats/minute.

Question 9

What is fetal bradycardia?

Answer 9

Fetal bradycardia is an FHR of <110 beats/minute.

Question 10

What is fetal tachycardia?

Answer 10

Fetal tachycardia is an FHR of >160 beats/minute.

Question 11

Definition of wandering baseline in FHR?

Answer 11

An unsteady baseline rate that wanders between 110 and 160 beats/minute.

Question 12

Significance of a wandering baseline in FHR?

Answer 12

Rare finding suggestive of a neurologically abnormal fetus, possibly a preterminal event.

Question 13

What is beat-to-beat variability?

Answer 13

Baseline FHR fluctuations of two cycles per minute or greater.

Question 14

Interpretation of beat-to-beat variaility?

Answer 14

Normal variability: 6 to 25 beats/minute.

Diminished variability: May indicate a seriously compromised fetus.

Question 15

What are cardiac arrhythmias in FHR?

Answer 15

Baseline bradycardia, tachycardia, or abrupt baseline spiking.

Question 16

What does intermittent bradycardia indicates?

Answer 16

Often due to congenital heart block.

Question 17

Types of sinusoidal heart rate pattern, and what causes it?

Answer 17

True sinusoidal pattern: Severe fetal anemia, caused by:

1. D-isoimmunization.
2. Ruptured vasa previa.
3. Twin-to-twin transfusion.

Insignificant sinusoidal pattern: May follow narcotic administration, with beat-to-beat variability still >6 cycles per minute.

Question 18

What are periodic fetal heart rate (FHR) changes?

Answer 18

Deviations from baseline FHR that are related to uterine contractions.

Question 19

Definition of FHR accelerations?

Answer 19

Increase in FHR >15 beats/minute >15 seconds above baseline.

Question 20

Causes of FHR accelerations?

Answer 20

1. Fetal movements
2. Uterine contractions
3. Pelvic examination
4. Fetal scalp blood sampling

Question 21

Significance of FHR accelerations?

Answer 21

Almost always reassuring, confirming the fetus is not acidemic at that time.

Question 22

Definition of FHR decelerations?

Answer 22

Decrease in FHR < 15 beats/minute for > 15 seconds below baseline.

Question 23

Classification of FHR decelerations?

Answer 23

Based on timing relative to uterine contractions:

a) Early decelerations (Type I).

b) Late decelerations (Type II).

c) Variable decelerations (Type III).

Question 24

What causes early decelerations (Type I), and what is their clinical significance?

Answer 24

Cause: Fetal head compression.

Significance: Usually benign and not associated with fetal distress, lowest point at same time with peak of contractions.

Question 25

What causes late decelerations (Type II), and what is their clinical significance?

Answer 25

Cause: Utero-placental insufficiency. Significance: Indicates fetal hypoxia or acidemia, requiring immediate intervention, lowestoft after peak of uterine contractions.

Question 26

What causes variable decelerations (Type III), and what is their clinical significance?

Answer 26

Cause: Umbilical cord compression. Significance: May be concerning if prolonged or severe.

Question 27

What is an admission CTG?

Answer 27

A short-term cardiotocography (CTG) performed on admission to monitor fetal heart rate in low-risk pregnancies.

Question 28

When is continuous EFM indicated in low-risk pregnancies?

Answer 28

When abnormalities in the fetal heart rate are identified during admission CTG.

Question 29

What are potential complications of internal EFM electrodes?

Answer 29

1. Fetal injuries: Scalp or eye injuries. 2. Placental blood vessel injury: Leading to hemorrhage. 3. Uterine perforation: From catheter placement. 4. Infection risk: Increased for both mother and baby.

Question 30

Why is the risk of infection higher with internal EFM?

Answer 30

The invasive nature of internal electrodes increases the likelihood of infection in both mother and fetus.

Question 31

What is fetal scalp blood sampling.

Answer 31

- Fetal scalp blood is obtained with - an illuminated fetoscope - through the dilated cervix, - and pH of the capillary blood is measured.

Question 32

pH interpretation of fetal scalp blood sampling?

Answer 32

pH interpretation: >7.25: Reassuring; continue labor observation. 7.20-7.25: Borderline; repeat in 30 minutes. <7.20: Repeat immediately; if acidemia is confirmed, consider immediate delivery.

Question 33

What is fetal scalp stimulation, and what does it assess?

Answer 33

Definition: Stimulation of the fetal scalp (e.g., using Allis forceps) to observe FHR acceleration. Significance: 1. Acceleration present: Normal pH (>7.20). 2. No acceleration: May indicate fetal acidemia (pH <7.20).

Question 34

What is fetal pulse oximetry, and is it widely used?

Answer 34

Definition: Measures fetal oxygen saturation using technology similar to adult pulse oximetry. Status: Still under evaluation before clinical adoption.

Question 35

What is vibro-acoustic stimulation?

Answer 35

Definition: An electronic artificial larynx stimulates the fetus via the maternal abdomen to assess FHR response.

Question 36

How is vibro-acoustic stimulation interpreted?

Answer 36

Normal: FHR acceleration >15 bpm lasting 15 seconds, occurring within 15 seconds after stimulation, with prolonged fetal movements. Abnormal: Only 50% correlate with acidotic pH.

Question 37

What is fetal electrocardiography, and what does it monitor?

Answer 37

Analyzes fetal ECG changes (S-T segment and P-R interval) to detect fetal hypoxia.