CTG

Question 1

It is common to have a baseline heart rate of between 100-120 bpm in the following situations:

Answer 1

-Postdate gestation
-Occiput posterior or transverse presentations

Question 2

Severe prolonged bradycardia (less than 80 bpm for more than 3 minutes) indicates what ? What are causes it?

Answer 2

severe hypoxia.

Causes of prolonged severe bradycardia include:
-Prolonged cord compression
-Cord prolapse
-Epidural and spinal anaesthesia
-Maternal seizures
-Rapid fetal descent

Question 3

What are the non-reassuring variability ? And the abnormal one ?

Answer 3

Non-reassuring:
less than 5bpm for between 30-50 minutes
more than 25bpm for 15-25 minutes
Abnormal:
less than 5bpm for more than 50 minutes more than 25bpm for more than 25 minutes sinusoidal

Question 4

Reduced variability can be caused by any of the following:

Answer 4

Fetal sleeping – this should last no longer than 40 minutes (most common cause) Fetal acidosis (due to hypoxia) – more likely if late decelerations are also present Fetal tachycardia
Drugs – opiates / benzodiazepines / magnesium sulphate
Prematurity – variability is reduced at earlier gestation (<28 weeks)
Congenital heart abnormalities

Question 5

Early deceleration due to:

Answer 5

increased fetal intracranial pressure causing increased vagal tone.

Question 6

Accelerations before and after a variable deceleration are known as the

Answer 6

“shoulders of deceleration”

Question 7

Reduced uteroplacental blood flow can occur due to:

Answer 7

1
Maternal hypotension Pre-eclampsia
Uterine hyperstimulation

Question 8

A prolonged deceleration is defined as a deceleration that lasts more than

Answer 8

3 minutes.
If it lasts between 2-3 minutes it is classed as non-reassuring.
If it lasts longer than 3 minutes it is immediately classed as abnormal.

Question 9

A sinusoidal pattern usually indicates one or more of the following:
.

Answer 9

Severe fetal hypoxia/asphyxia
Severe fetal anaemia Fetal/maternal haemorrhage
Intracranial haemorrhage
Also described with chorioamnionitis and fetal distress and umbilical cord occlusion

Question 10

What are concerning characteristics of variable decelerations?

Answer 10

Lasting more than 60 seconds
Reduced baseline variability within the deceleration Failure to return to baseline
Biphasic (W) shape
No shouldering

Question 11

What are the indications for fetal blood sampling?

Answer 11

• Persistent late or variable -decelerations on CTG Persistent fetal tachycardia
  -Prolonged loss of baseline variability.
• any signs of fetal compromise
• low 5 min APGAR score
• severe fetal growth restriction
• maternal thyroid disease
• multifetal gestation
  -Significant meconium stained liquor (grade 2/3) along with any CTG abnormality

Question 12

Contraindications of FSE:

Answer 12

-active genital herpes infection, -seropositive to hepatitis B, C, D, E, or to human immunodeficiency virus 10,11, - suspected fetal blood disorders,
-uncertainty about the presenting part, or when artificial rupture of membranes is inappropriate (i.e. an unengaged presentation).
-very preterm fetuses (under 32 weeks gestation)

Question 13

Indications of FSE:

Answer 13

. If an acceptable record cannot be obtained with external monitoring or if a cardiac arrhythmia is suspected

Question 14

Sinusoidal pattern when it consider pathological or physiological ?

Answer 14

> 20 min pathological
< 20 min might be physiological

Question 15

Define variable decelerations

Answer 15

The onset of the deceleration to the nadir should be less than 30 seconds. The decrease from the fetal heart rate baseline should be at least 15 beats per minute and should last for at least 15 seconds, but less than 2 minutes.
-can be periodic, meaning they are associated with contractions, or they can be episodic and not associated with uterine contractions.
-Small variable decelerations are often present in the fetal heart tracings of premature fetuses.

Question 16

The definition of a significant deceleration was

Answer 16

• Variable decelerations reaching a nadir more than 60 beats per minute below the baseline and lasting longer than 60 seconds
• Variable decelerations reaching a nadir of fewer than 60 beats per minute regardless of baseline and lasting longer than 60 seconds
• Any late deceleration
• Any prolonged deceleration (lasting 2 minutes or longer)

Question 17

The differential diagnosis for recurrent variable decelerations includes:

Answer 17

•Intrauterine umbilical cord compression
Maternal/fetal positioning
Low fluid or oligohydramnios
Nuchal cord or other cord entanglements
True knot or short umbilical cord
Uterine tachysystole
Pushing efforts during the second stage of labor
•Increasing fetal acidemia
•Umbilical cord prolapse
•Uterine rupture

Question 18

sinusoidal CTG pattern has the following characteristics:

Answer 18

A smooth, regular, wave-like pattern Frequency of around 2-5 cycles a minute Stable baseline rate around 120-160bpm No beat to beat variability.
Pearl:
(Insignificant sinusoidal pattern can be seen with opiods administration -like meperidine- but an important characteristic of this pattern when due to narcotics is the sine frequency is 6 cycles per min)

Question 19

Remember the ‘Rule of 3’ for fetal bradycardia:

Answer 19

3 minutes – call for help

6 minutes – move to theatre

9 minutes – prepare for assisted delivery

12 minutes – aim to deliver the baby.

The pH of the fetus has been shown to drop at the rate of 0.01 every 2–3 minutes.

Question 20

the CTG false-positive rate of cerebral palsy prediction is as high as

Answer 20

99.8%

Question 21

the National Institute of Child Health and Human Development Fetal Monitoring Workshop defined acceleration waveforms based on gestational age (Macones, 2008). In fetuses at or beyond 32 weeks’ gestation, the acceleration acme is ≥– beats per minute (bpm) above the baseline rate, and the acceleration lasts ≥– seconds but <2 minutes. Before 32 weeks, accelerations are defined as having a rise ≥– bpm above baseline for ≥– seconds.

Answer 21

the National Institute of Child Health and Human Development Fetal Monitoring Workshop defined acceleration waveforms based on gestational age (Macones, 2008). In fetuses at or beyond 32 weeks’ gestation, the acceleration acme is ≥15 beats per minute (bpm) above the baseline rate, and the acceleration lasts ≥15 seconds but <2 minutes. Before 32 weeks, accelerations are defined as having a rise ≥10 bpm above baseline for ≥10 seconds.

Question 22

terminal cardiotocogram included:

Answer 22

(1) baseline variability <5 bpm, (2) absent accelerations, and (3) late decelerations with spontaneous uterine contractions.

Question 23

Causes of fetal tachycardia

Answer 23

The most common explanation is maternal fever. In some cases, fetal tachycardia may precede overt maternal fever (Gilstrap, 1987). Fetal tachycardia caused by maternal infection typically is not associated with fetal compromise unless it is associated with fetal sepsis or with significant FHR decelerations.
Other causes of fetal tachycardia include fetal compromise, cardiac arrhythmias, and maternal administration of parasympathetic inhibiting (atropine) or sympathomimetic (terbutaline) drugs. Prompt treatment of the compromising event, such as alleviation of maternal fever or volume resuscitation, can result in fetal recovery. The key feature to distinguish fetal compromise in association with tachycardia seems to be concomitant FHR decelerations (Cahill, 2018).

Question 24

Causes of fetal tachycardia

Answer 24

The most common explanation is maternal fever. In some cases, fetal tachycardia may precede overt maternal fever (Gilstrap, 1987). Fetal tachycardia caused by maternal infection typically is not associated with fetal compromise unless it is associated with fetal sepsis or with significant FHR decelerations.
Other causes of fetal tachycardia include fetal compromise, cardiac arrhythmias, and maternal administration of parasympathetic inhibiting (atropine) or sympathomimetic (terbutaline) drugs. Prompt treatment of the compromising event, such as alleviation of maternal fever or volume resuscitation, can result in fetal recovery. The key feature to distinguish fetal compromise in association with tachycardia seems to be concomitant FHR decelerations (Cahill, 2018).

Question 25

Causes of diminished fetal variability

Answer 25

diminished variability, when it reflects fetal compromise, likely reflects acidemia rather than hypoxia. Severe maternal acidemia also can lower fetal variability, for example, in a mother with diabetic ketoacidosis. Another common cause of diminished variability is administration of some analgesic drugs during labor (Chap. 25, p. 477). These can depress the central nervous system and include narcotics, barbiturates, phenothiazines, tranquilizers, and general anesthetics. As one specific example, variability regularly diminishes within 5 to 10 minutes following intravenous (IV) meperidine administration, and the effects may last 60 minutes or longer (Hill, 2003; Petrie, 1993). IV butorphanol has similar effects (Schucker, 1996). And, chronically administered buprenorphine suppresses FHR and movement (Jansson, 2017). Corticosteroids also decrease fetal movement and thereby dampen variability (Noben, 2019).
Magnesium sulfate can diminish variability