Chapter 16 CTG

Dr Areefa Albahri

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FHR as a screening test

• Intrapartum FHR monitoring is a screening test that provides information to alert the clinician that a true test for fetal welfare assessment needs to be performed, eg:

An atypical variable (pathological feature) fetal blood sampling should be performed

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FHR evaluationDr C Bravado ALSO

• DR – determine the risk• C – contractions• Bra – baseline rate• V – variability• A – accelerations• D – decelerations• O – overall assessment (followed by a

management plan)

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FHR Monitoring on admission in labour

• ??? Electronic FHR monitoring• ??? Doppler auscultation• ??? Pinards

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Who should have continuous electronic FHR monitoring?

• Antenatal risk factors– Prematurity– Pre-eclampsia/eclampsia– Diabetes– Growth restriction– Non-reassuring antenatal fetal welfare assessment– Multiple pregnancy– Malpresentation

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Who should be have continuous electronic FHR monitoring?

• Intrapartum factors– Syntocinon– Meconium– Epidural– Suspicious FHR on auscultation– Prolonged rupture of the membranes– Prematurity– Previous C/S

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Practice Recommendations for intermittent auscultation

• Healthy women with uncomplicated labour IA with Pinards/Doppler recommended

• Active labour- after contraction for at least 60 seconds & at least

every 15mins 1st stageevery 5mins 2nd stage

• Continuous EFM is recommended if: Baseline < 110 or >160bpm; Decelerations or intrapartum risk factors develop

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Categorization of FHR Features

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Baseline rate• Normal = 110 – 160bpm• Bradycardia (moderate) = 100 – 109bpm• Bradycardia (abnormal) = < 100 bpm• Tachycardia (moderate) = 161 – 180 bpm• Tachycardia (abnormal) = >180 bpm

(RCOG)

• VariabilityGreater than 5bpm and less than 25bpm

• Increased variability is often seen following an acute hypoxic event.

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Baseline Rate

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Baseline Bradycardia

• Bradycardia (moderate) = 100 – 109bpm• Bradycardia (abnormal) = < 100 bpm• Rare • Consider the cause if this is a sudden event – ?

prolonged deceleration

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Causes of Baseline Tachycardia

• Excessive fetal movement• Maternal dehydration• Prematurity• Maternal fever• Maternal or fetal stress causing adrenaline

release• Chorioamnionitis

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Causes of Reduced Variability

• = 5bpm fetal sleep or quiet state• Maternal medications – Morphine, Pethidine

etc• Fetal hypoxia – depressing the CNS• Fetal anomalies• Fetal Cardiac Arrhythmias

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Sinusoidal

• Wave like pattern of 3 – 5 oscillation / min ranging between 5 – 15 beats

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Decelerations

• Early• Late• Variable – typical and atypical• Prolonged

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Early

• Repetitive from one contraction to another• Recovery to baseline is always at the end on

the contraction• Caused by vagal nerve stimulation

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Late Decelerations

• Repetitive from one contraction to the next (3 or more)

• Recovery to baseline is late, well after the end of the contraction

• More ominous when associated with minimal variability & baseline

• Reflects a change in placental ability to adequately meet fetal needs

• May indicate the presence of fetal hypoxia and acidosis

• Often signifies fetal decompensation

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The Fetal Heart Rate – Late decelerations

• Lates represent fetal hypoxia and are related to an interruption in O2 supply at cardiac level

• Reduced O2 leads to stimulation of chemoreceptors• Results in activation of the cardiac centres in the brainstem• SA node is effected and the FHR slows.• With the prolonged hypoxia, myocardium is effected causing further

decrease in the FHR and hypotension• Recovery is slower as the myocardium gradually reoxygenates

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Variable Decelerations

• Repetitive or intermittent• Rapid sudden fall in FHR• Often rapid recovery• Reflect some degree of umbilical cord

impingement• Often seen when liquor volume is

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Shoulders

Baseline Rate

Typical variables

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1cm per min

Baseline Rate Overshoot

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Prolonged Decelerations

• FHR falls for > 3 minutes• Usually associated with an acute insult - Top

up, VE, Syntocinon• FHR pattern before and in recovery indicates

fetal tolerance - not the deceleration itself• Should be managed vigorously

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Suspicious FHR Pattern: What should you do?

Maternal • Position• Dehydration• Infection• Hypotension• ?V.E/bedpan• Vomiting/vasovagal• Analgesia/Drugs

Mechanical• Poor quality CTG• Maternal pulse• Transducer site• FSE• Oxytocics• Prostaglandins

Typical variable decelerations

Typical variable decelerations occur in response to interment

cord compression and

are commonly seen during the second stage of labour. They

are quick to recover to the normal baseline, have normal

variability, last less than 2 minutes and have evidence of

shouldering, which is a normal physiological response to

intermittent cord compression.

Atypical variable decelerations

These decelerations can be an indicator of hypoxia and have some or all of

the following features:

Loss of acceleration (shouldering) before and after deceleration

Delayed recovery back to baseline

Rebound tachycardia – caused by catecholamine release in response to

stress

Loss of variability/change in baseline rate.

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That is All

Thanks