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Y4 - GOSH > Cardiotocography (CTG) Interpretation > Flashcards

Cardiotocography (CTG) Interpretation Flashcards

(46 cards)

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1
Q

How is fetal monitoring achieved in low risk pregnancies?

A
  • intermittent auscultation to listen to the fetal heart
  • this is acheived through Doppler
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2
Q

How is fetal monitoring acheived in high risk pregnancies?

A

continuous monitoring with CTG

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3
Q

What features may make a pregnancy become “high risk” and require CTG monitoring?

A
  • intrauterine growth restriction (IUGR)
  • multiple pregnancy
  • meconium stained liquor
  • oxytocin infusion
  • abnormality on intermittent auscultation

meconium staining can be normal post 40 weeks gestation but is a sign of distress prior to this

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4
Q

What is measured on CTG?

A
  • fetal heart rate
  • contractions of the uterus
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5
Q

What are arrows A-D pointing at?

A

A - fetal heart rate in bpm

B - fetal movements (mother presses button when she feels movement)

C - fetal movements (detected by the computer)

D - uterine contractions

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6
Q

What is a fetal scalp electrode?

A

an instrument that screws into the scalp to monitor the fetal HR

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7
Q

When is a fetal scalp electrode used?

A
  • obesity
  • twins
  • abdominal scarring
  • poor quality trace with abdominal transducer

it should be AVOIDED in blood-borne viruses / haemophilia

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8
Q

What are the indications for continuous CTG monitoring in labour?

A
  • sepsis
  • maternal tachycardia (>120)
  • significant meconium
  • pre-eclampsia
  • fresh antepartum haemorrhage
  • delay in labour
  • oxytocin use
  • disproportionate maternal pain
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9
Q

What are the 5 components of the CTG?

A

contractions:

  • the number of uterine contractions per 10 mins

baseline rate:

  • baseline fetal HR

variability:

  • how the fetal HR varies up and down around the baseline

accelerations:

  • periods where the fetal HR spikes

decelerations:

  • periods where the fetal HR drops
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10
Q

What is the normal rate for contractions?

A

4 or 5 contractions should occur every 10 mins whilst in labour

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11
Q

Why is it important to interpret uterine contractions?

A
  • contractions are used to gauge the actvity of labour
  • too few contractions indicates that labour is not progressing
  • too many contractions indicates uterine hyperstimulation + risk of fetal compromise
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12
Q

What is a normal baseline rate?

A

110 - 160 bpm

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13
Q

What is a normal value for variability?

A

5 bpm or more

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14
Q

How can baseline rate and variability be described?

A
  • reassuring
  • non-reassuring
  • abnormal
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15
Q

What is a reassuring baseline rate / variability?

A

baseline rate:

  • between 110 - 160 bpm

variability:

  • between 5 - 25
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16
Q

What is a non-reassuring baseline rate / variability?

A

baseline rate:

  • 100 - 109 bpm

OR

  • 161 - 180 bpm

variability:

  • < 5 for 30-50 mins

OR

  • > 25 for 15-25 mins
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17
Q

What is an abnormal baseline rate / variability?

A

baseline rate:

  • below 100 or above 180

variability:

  • < 5 for over 50 mins

OR

  • > 25 for more than 25 mins
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18
Q

What is an acceleration?

A
  • a rise of > 15bpm for 15 seconds
  • accelerations occurring alongside uterine contractions is a sign of a healthy fetus

the absence of accelerations with an otherwise normal CTG is not necessarily a concerning sign

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19
Q

What is a deceleration?

Study These Flashcards
A
  • a fall of > 15 bpm for > 15 seconds
  • this is a sign of fetal distress
20
Q

What aspects of uterine contractions are assessed?

Study These Flashcards
A
  • count how many contractions occur in 10 mins (each square = 1 min)
  • assess duration of the contractions
  • assess intensity by palpating the abdomen

the CTG does NOT give any indication of contraction intensity

this must be gauged by palpating the abdomen

21
Q

How is the baseline rate calculated?

Study These Flashcards
A
  • look at the CTG and assess what the average heart rate has been over the last 10 mins
  • ignore any accelerations or decelerations
22
Q

How is variability calculated?

Study These Flashcards
A
  • by assessing how much the peaks / troughs of the HR deviate from the baseline rate
23
Q

Why are decelerations a concerning sign?

Study These Flashcards
A
  • the fetal HR drops in response to hypoxia
  • it is slowing down to conserve energy for vital organs
24
Q

What are the 4 types of deceleration?

Study These Flashcards
A
  1. early decelerations
  2. late decelerations
  3. variable decelerations
  4. prolonged decelerations
25
What are early decelerations?
* early decelerations are related to uterine contractions * they **start when the contraction begins** and **recover when the contraction stops**
26
What causes an early deceleration?
* the **uterus compresses the fetal head**, which stimulates the vagus nerve and slows the HR * this is **NOT pathological**
27
What is a late deceleration?
late decelerations **begin at the peak of uterine contraction** and **recover when the contraction ends**
28
What causes a late deceleration?
**insufficient blood flow** to the uterus + placenta due to: * maternal hypotension * pre-eclampsia * uterine hyperstimulation this can result in **fetal hypoxia + acidosis**
29
What are variable decelerations?
* a **rapid fall in baseline** fetal HR with a **variable recovery phase** * their **duration is variable** and they ***do NOT*** have a relationship to **uterine contractions**
30
Describe the course of a variable deceleration
* there is a **fall of > 15 bpm** from the baseline * the **lowest point** of the deceleration occurs **within 30 seconds** * the deceleration lasts for **< 2 mins** in total
31
How are variable decelerations described?
in terms of **depth** and **duration**
32
What do variable accelerations indicate?
* **intermittent compression of the umbilical cord**, causing fetal hypoxia * they are normally seen during **labour** + in women with **reduced amniotic fluid volume**
33
What are the shoulders of deceleration?
* **accelerations** that occur **before and after** a variable decleration * their presence indicates the fetus is **not yet hypoxic** + is adapting to redcued blood flow
34
What is a prolonged deceleration?
a decleration that lasts for **more than 2 minutes**
35
When is a CTG described as reassuring in terms of decelerations?
* there are **no declerations** * there are **early decelerations** * there are **< 90 seconds** of **variable decelerations** with no concerning features
36
What features of decelerations can make then non-reassuring or abnormal?
* regular variable decelerations / late decelerations can be abnormal or non-reassuring depending on their features * **prolonged decelerations** are always **abnormal**
37
How can a CTG be categorised based on baseline rate, declerations + variability?
**normal** **suspicious:** * a single non-reassuring feature **pathological:** * 2 non-reassuring features OR * a single abnormal feature **need for urgent intervention:** * acute bradycardia OR * prolonged decleration for > 3 mins
38
What is the "rule of 3s" for fetal bradycardia?
* 3 mins - call for help * 6 mins - move to theatre * 9 mins - prepare for delivery * 12 mins - delivery of the baby (by 15 mins)
39
What is a sinusoidal CTG pattern?
* indicates **severe fetal compromise** * pattern is similar to a sine wave * **stable baseline rate** around 120-160bpm with **no beat to beat variability**
40
What can a sinusoidal CTG indicate?
* severe fetal hypoxia * severe fetal anaemia * fetal / maternal haemorrhage
41
What is fetal bradycardia? When does it become more concerning?
* a baseline HR **< 110 bpm** * ***severe prolonged bradycardia*** occurs when the **HR < 80** for more than **3 mins**
42
What are the causes of prolonged severe bradycardia?
* prolonged cord compression * cord prolapse * epidural / spinal anaesthesia * maternal seizures * rapid fetal descent
43
When is it normal to have a baseline rate of 100-120bpm?
* postdate gestation OR * occipitoposterior / transverse presentations
44
What are the possible causes of reduced variability?
* **fetal sleeping** (should last < 40 mins) * **fetal acidosis** (due to hypoxia) * fetal tachycardia * drugs * **prematurity** (reduced < 28 weeks gestation) * congenital heart abnormalities ## Footnote fetal acidosis is more likely if decelerations are also present
45
What drugs are associated with reduced variability?
* methyldopa * opiates * benzodiazepines * magnesium sulphate
46
What would you want to do if a CTG was non-reassuring or abnormal?
**fetal blood sample** * this assesses for fetal acidosis * determines the need for emergency LSCS

Y4 - GOSH (62 decks)

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