CTG, partogram and GROW scan interpretations

Question 1

What does CTG stand for?

Answer 1

Cardiotocography is used in pregnancy to monitor fetal heart rate and contractions of the uterus

Question 2

How does a CTG work?

Answer 2

• Via two transducers onto the maternal abdomen
  
  • one monitors fetal HR
  • one monitors contractions via tension on the abdominal wall

Question 3

What is the anagram used to interpret CTG’s and what does this stand for?

Answer 3

DR C BRAVADO

DR - Define Rate

C - Contractions

BRa- Baseline Rate

V - Variability

AD - Accelerations and Decelerations

O - Overall impression

Question 4

DR - Define Risk is for what?

Answer 4

To assess if the pregnancy is low or high risk to give context to the CTG

eg;

• GDM
• HTN
• Asthma
• Previous C-section
• Congenital malformations
• IUGR
• PTL

Question 5

C - Contractions

What do you want to assess

Answer 5

Record the number of contractions present over a ten minute period

Each big square on the example CTG chart below is equal to one minute, so look at how many contractions occurred within 10 big squares.

Assess the contractions for:

• Duration: little sq: 30 seconds
• Intensity: can only assess via palpation NOT CTG

Question 6

BRa - Baseline rate of the fetal heart. What do you want to know?

Answer 6

BRa: baseline heartrate of the fetus within a 10min window

***a normal fetal heart rate is 110-160 bpm***

this will increase with prematurity

Question 7

Fetal tachycardia is ____ and some common causes are?

Answer 7

>160 bpm

• Fetal hypoxia
• Chorioamniotis (if maternal fever also present)
• Hyperthyroidism
• Fetal/maternal anaemia
• Feta arrhythmia

Question 8

Fetal tachycardia is ____ and common causes are?

Answer 8

<110bpm

• Postdate gestation
• occiput posterior or transverse positions

Causes of prolonged or severe bradycardia are:

• Prolonged cord compression
• Cord prolapse
• Epidural or spinal anaesthesia
• Rapid fetal descent
• Maternal seizures

Question 9

V - Variability: what do you want to know

Answer 9

the variation of fetal heart rate from one beat to the next.

Variability occurs as a result of the interaction between the nervous system, chemoreceptors, baroreceptors and cardiac responsiveness. Indicator of how healthy a fetus is at that particular moment in time/ability to adapt.

Reassuring: 5-25bpm (~15bpm for 15 mins)

Concerning:

• <5bpm for >30-50mins
• >25 for >25mins

Question 10

What can cause reduced variability

Answer 10

• Fetal acidosis due to hypoxia
• Fetal sleeping (<40mins)
• Fetal tachycardia
• Drugs; opiates, benzos
• Prematurity
• congential heart abnormalities

Question 11

Definition of an ‘acceleration’

Answer 11

increase of over 15bpm for over 15 seconds

this is reassuring, and is a signof a healthy fetus

Question 12

Definition of an ‘decceleration’

Answer 12

decrease of 15bpm for over 15 seconds

Early deccel: due to intracranial pressure (increasing vagal tone) from contractions

Late deccel: begin at peak of uterine contraction and continue after, indicates there is insufficient blood flow to the uterus and placenta which can cause fetal hypoxia and acidosis.

Prolonged Decel: 2-3mins is ‘non-reassuring’, >3mins is ‘abnormal’

Variable Decelerations: rapid fall in baseline fetal heart rate with a variable recovery phase, may not have any relationship to uterine contractions. Can be due to cord compression

Question 13

What should you do when faced with late or prolonged decelerations

Answer 13

Check fetal blood pH for acidosis.

If fetal blood pH is acidotic it indicates significant fetal hypoxia and the need for emergency C-section.

Question 14

O - overall impression

Answer 14

was the CTG

• Reassuring*
• Suspicious*
• Abnormal*

Question 15

What two things in a fetal USS can confirm with certainty a miscarriage?

Answer 15

• CRL >7mm and no fetal cardiac activity OR
• Mean gestational sac diameter >25mm and an empty gestational sac