Basic Practical Skills - Obstetrics Flashcards

1
Q

What is the function of the cardiotocography (CTG)?

A

Used during pregnancy to monitor fetal heart and uterine contractions

  • detects early signs of fetal distress
  • commonly used in third trimester
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2
Q

What should be done in the event of an abnormal CTG?

A

Invasive investigations

Emergency C-section considered early

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3
Q

How are CTGs read?

A
Dr - define risk
C - contractions
Bra - baseline rate
V - variability 
A - accelerations 
D - decelerations 
O - overall impression
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4
Q

How do you define risk when reading a CTG?

A
Is pregnancy high or low risk (high risk pregnancies have lower threshold for intervention)
Maternal factors 
- gestational diabetes
- hypertension 
- asthma 
Obstetric complications 
- multiple gestation
- post-date gestation 
- previous C-section 
- IUGR
- premature rupture of membranes 
- congenital malformations 
- induced/augmented labour 
- pre-eclampsia 
Other factors 
- no antenatal care
- smoking
- drug abuse
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5
Q

How are contractions assessed on CTG?

A

Number of contractions in a 10 minute period (big square on CTG = 1 minute)
Individual contractions are seen as peaks on CTG monitoring - uterine acitvity
Assess for
- duration
- intensity (can only be assessed using palpation)

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6
Q

How is the baseline rate assessed on CTG?

A

Average heart rate of a fetus within a 10 minute window (ignoring accelerations and decelerations)
- normal HR 110-150bpm

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7
Q

What are the causes of fetal tachycardia (>160bpm) on CTG

A
Fetal hypoxia
Chorioamnionitis - maternal fever 
Hyperthyroidism 
Fetal or maternal anaemia
Fetal tachyarrhythmia
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8
Q

Causes of fetal bradycardia (<100bpm) on CTG

A

Mild bradycardia (100-120bpm) is common in postdate gestation or in occiput posterior or transverse presentation
Severe prolonged (<80bpm for more than 3 mins) bradycardia
- prolonged cord compression
- cord prolapse
- epidural and spinal anaesthesia
- maternal seizure
- rapid fetal decent

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9
Q

How is fetal bradycardia managed?

A

If the cause can’t be corrected - immediate delivery of fetus is required

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10
Q

How is variability assessed on CTG

A

Variation of fetal heart rate from one beat to the next
- occurs due to interaction between nervous system, chemoreceptors, cardiac responsiveness and baroreceptors
- a healthy fetus constantly adapts to changes in the environment
Normal between 5-25bpm above/below baseline
- less than 5bpm variation for >50 mins is abnormal
- more than 25 bpm variation for >25 min is abnormal

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11
Q

What are the causes of reduced variability

A
Fetus sleeping (<40 mins normal)
Fetal acidosis due to hypoxia 
Tachycardia 
Drugs
- opiates and benzos
Prematurity
- before 28 weeks 
Congenital heart abnormalities
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12
Q

How are accelerations assessed on CTG

A

Abrupt increase in baseline heart rate >15bpm for >15 seconds

  • presence is reassuring
  • healthy = occurs alongside contractions
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13
Q

How are declarations assessed on CTG

A

Abrupt decrease in baseline heart rate >15bpm for >15 seconds
Can be pathological/non-pathological depending on the situation

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14
Q

When are decelerations normal on a CTG

A

During labour

  • timed with contractions (early decelerations) due to increased fetal intracranial pressure
  • increased vagal tone
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15
Q

What are variable declarations on a CTG

A

Variable decelerations are a rapid fall in baseline heart rate and variable recovery phase
- variable in duration
- aren’t related to contractions
Require close monitoring if become persistent
Presence of accelerations as well are reassuring

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16
Q

What are the causes of variable decelerations on CTG

A

Umbilical cord compression
- vein occluded first: initially causes an acceleration in response
- artery occluded next: rapid deceleration
Can resolve if the mother change position (baseline rate returns once pressure is released)

17
Q

How are late decelerations assessed on CTG

A

Begin at the peak of contractions and recover once contraction has ended
Indication of insufficient blood flow to the uterus and placenta
- fetal hypoxia and acidosis
Fetal sampling needed to assess severity
- if acidotic, emergency C-section is required

18
Q

Causes of late decelerations on CTG

A

Maternal hypotension
Pre-eclampsia
Uterine hyperstimulation

19
Q

What are prolonged decelerations on CTG

A

2 or 3 minutes of deceleration (non-reassuring)

Over 3 minutes is very abnormal

20
Q

What are sinusoidal decelerations on CTG

A
Smooth, regular, wave-like pattern on CTG
Causes
- severe fetal hypoxia 
- severe fetal anaemia 
- fetal or maternal hemorrhage
21
Q

How is the overall impression of a CTG assessed

A
All aspects are assessed
- determined by how many individual features are reassuring, suspicious or abnormal 
Give overall impression 
- reassuring 
- suspicious
- abnormal 
Mention in notes