CTG: patterns

Aboubakr Elnashar

Benha University Hospital, EgyptAboubakr Elnashar

I. Basal Heart Rate Activity

1. Rate: Normal:110-160 increment 5 bpm (10 m segment)

Bradycardia: < 110 bpm

Tachycardia: > 160bpm

2. Variability Short term= instantaneous (beat to beat v.)

Long term= oscillatory changes in 1 m

3. Sinusoidal: Mild is due to sedation

Marked is due to fetal anemia

4. Arrhythmia: Abrupt spiking, bradycardia or tachy

II. Periodic heart rate Activity

1. Acceleration

2. Deceleration Early

Late

variable

prolongedAboubakr Elnashar

I. Baseline

Tachycardia

Baseline FHR > 160 bpm

Bradycardia

Baseline FHR < 110 bpm

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1. NormalFHR in ten beat

intervals ranging

from 30 bpm to

240 bpm.

Normal FHR is 110

to 160 bpm

1. RATE

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The mean FHR

rounded to increments of 5 bpm during a 10-min

segment, excluding:

— Periodic or episodic changes

— Periods of marked FHR variability

— Segments of baseline that differ > 25 bpm

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Determining the Baseline

Each red line indicates a 2 minute

In any 10 minute segment, the minimum baseline

duration is 2 minutes within the 10 minute segment.

Baseline Rate: 130/mAboubakr Elnashar

2. Tachycardia:FHR ≥160bpm

Fetal tachycardia with fetal

arrhythmia

Severe

tachyAboubakr Elnashar

Uncomplicated baseline tachycardia:161-180 bpm:

Not associated with poor NN outcome.

Mild

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Common Causes of Fetal Tachycardia

Maternal

1. Fever/infection (Amnionitis)

2. Anxiety

3. Drugs:

Anticholinergic: Atropine

Beta sympathomimetic:

Terbutaline

Illicit: Cocaine,Methylamphetamines

Fetal

1. Hypoxia

2. Anemia

3. Cardiac arrhythmias

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3. Bradycardia: baseline FHR ≤110 bpm

• Mild: 100 –110 bpm

• Moderate: 80-100 bpm

• Severe: < 80 bpm

Mild: not associated with poor neonatal outcome.

Prolonged: FHR < 100/ min for 3 min or

< 80 for 2 min

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Causes of bradycardia

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2. VARIABILITY

Changes in the FHR

{interaction of the sympathetic and parasympathetic

systems of the fetus}.

Define:

Fluctuations in the FHR of more than 2 cycles

pm or greater

Amplitude=distance between the highest point

and the lowest point of each of the fluctuation

These fluctuations are irregular in amplitude and

frequency.

The baseline must be for a minimum of 2 min in any 10-min segment

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Types

1. Short term:

Change of FHR from one beat to the next

[Time between cardiac systoles]

in internal fetal scalp electrode

2. Long term:

Oscillation of FHR around baseline /min

[2-6 cycles or waves/min]

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long-term beat-to-beat variability

ranging between 125 and 135 bpm.

Defined as 3-5 cycle/min

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Quantification=degrees

1. Absent:

amplitude range undetectable

2. Minimal:

amplitude range detectable but 5 bpm

3. Moderate (normal):

amplitude range 6–25 bpm

4. Marked:

amplitude range > 25 bpm

What is FHR baseline?

Whether variability exists?

What is Degree?

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To calculate variability you look at how much the peaks &

troughs of the HR deviate from the baseline rate (in bpm)

≥ 25 bpm amplitude range

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(1) Undetectable or absent

(2) Minimal variability:0 -5 bpmAboubakr Elnashar

4) Marked variability: >25 bpm

(3)Moderate variability: >5-<25 bpm

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A. lack of long-term variability

at 31 w during maternal

diabetic ketoacidosis (pH

6.09).

B. Recovery of fetal long- term

variability after correction of

maternal acidemia.

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Abnormal base line variability

Absent: Amplitude range is undetectable

Minimal:

Amplitude range ≤5bpm

Moderate: Amplitude range is 6-25bpm

Marked:

Amplitude range is >25 bpm

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Causes of Reduced variability

single most reliable sign of fetal compromise

• Foetus sleeping: should last no longer than 40 min

most common cause

• Foetal acidosis {hypoxia}

more likely if late decelerations also present

• Foetal tachycardia

• Drugs:Opiates

Benzodiazipine’s

Methyldopa

Mg sulphate

• Prematurity:

variability is reduced <28 w

• Congenital heart abnormalitiesAboubakr Elnashar

3. SINUSOIDAL HEART RATE

Define:

– Regular Oscillation of the Baseline long-term

Variability

– Resembling a Sine wave, with no BTBV.

– Amplitude: 5-15bpm

– 2- 5 cycle/m

– Absence of accelerations

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•Sinusoidal pattern associated with maternal IV meperidine

administration.

•Sine waves are occurring at a rate of 6 cycles/min.Aboubakr Elnashar

Causes

• Mild:

due to sedation

• Marked:

due to fetal anemia associated with:

• Rh isoimmunization

• Fetal hypoxia

• Chronic fetal bleeds

• Fetal-maternal hge

• Severe acidosisPSEUDOSINUSOIDAL

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II. Periodic heart rate Activity

Periodic changes:

accelerations or decelerations in FHR that occur in

direct association with uterine contractions.

Episodic (sporadic) changes:

accelerations or decelerations FHR that occur

independent of uterine contractions, in response to

vaginal exam

maternal vomiting

fetal movementAboubakr Elnashar

AccelerationPeriodic acc Sporadic acc

15bpm 15 sec

<32wks= 10 -10

Acceleration

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1. ACCELERATION

Define:

An increase in the FHR from the most recently

calculated baseline

Onset to peak:

less than 30 sec

The duration

Time from the initial change in FHR from the

baseline to the return of the FHR to the baseline

less than 2 minutes

Prolonged acceleration

lasts 2 min, but < 10 min

Baseline change

If an acceleration lasts 10 minAboubakr Elnashar

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Adequate accelerations:

>32 w

An acme: 15 bpm above baseline

Duration: 15 sec but < 2 min

< 32 w

An acme: 10 bpm above baseline

Duration: 10 sec but < 2 min

< 28 w

Amplitude of accelerations: lower than a

fetus ≥ 32w.

FHR baseline: higher

Variability: less

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Significance

Presence:

at least 2 accelerations/15 m

Reassuring

Sign of a healthy foetus

Absence with an otherwise normal CTG:

uncertain significance

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2. DECELERATION

1. Early deceleration

Define:

In association with a uterine

contraction

Start when uterine contraction

begins

Recover when uterine

contraction stops

Symmetrical=Nadir occurs at the

same time as the peak of the

contraction

Gradual=Onset to nadir:

30 sec or moreAboubakr Elnashar

Gradual decrease

in HR

Both onset and

recovery coincident

with the onset and

recovery of the

contraction.

Onset to Nadir:

30 seconds or more.

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Significance Physiological & not pathological

{increased foetal intracranial pressure causing increased

vagal tone}

Quickly resolves once the uterine contraction ends &

intracranial pressure reduces

May be prevented by avoiding early ROM

Mirror Image

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2. Late deceleration

Define:

In association with a uterine contraction

Gradual=onset to nadir 30 sec or more

decrease in FHR with return to baseline

Onset, nadir, and recovery of the deceleration

occur after the beginning, peak, and end of the

contraction, respectively

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Late deceleration.

Gradual decrease in the HR

Nadir and recovery occurring after the end of the contraction.

Nadir of deceleration occurs 30 seconds or more after the

onset of the deceleration. Aboubakr Elnashar

•Late

decelerations

{uteroplacental

insufficiency

resulting from

placental

abruption}.

Immediate CS

•Umbilical artery

pH: 7.05

• Po2: 11 mm Hg.

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Significance:

uteroplacental insufficiency:

hypoxia and metabolic abnormalities.

one of the most ominous FHR patterns

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Repetitive late deceleration:

increases risk of

Umbilical artery acidosis

Apgar score < 7 at 5 m

Cerebral palsy

If associated with decrease or

loss of BBV

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3. Variable deceleration

Define:Decrease in FHR of > 15 bpm measured from the most

recently determined baseline rate.

Abrupt=Onset to nadir: less than 30 seconds.

lasts > 15 sec and less than 2 min

onset commonly varying with successive contractions

may be v-shaped, u-shaped or w-shaped.

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W-shaped

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•Variable

decelerations

B ―shoulders‖ of

acceleration

compared with

deceleration A.

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FHR effects of partial

occlusion and

complete occlusion of

the umbilical cord

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• Pressure on the cord initially occludes the umbilical vein

acceleration (the shoulder of the deceleration): healthy

response.

• This is followed by occlusion of the umbilical artery sharp

down slope of FHR.

• Finally, the recovery phas {relief of the compression}

sharp return to the baseline another healthy brief

acceleration or shoulder

Variable deceleration with pre- and post-accelerations

(―shoulders‖). Aboubakr Elnashar

Significance

depends upon

how often they occur

how deep they go

how long they last.

how the fetus responds in their presence.

um cord compression

(Common: 50-80% 2nd stage)

Reassuring variable deceleration:Abrupt (sharp) onsetAbrupt return to baselinePreceded & followed by shoulders

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Complicated variable decelerations:

Deceleration

Role of 60

depth >60 bpm

for >60 seconds

rate of 60 bpm

Changes in shape: over-shoot

Slow recovery

Baseline FHR:

Decreased or increased following the

decelerations

BBV:

Absent in or between decelerations

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Re-assuring

a) Abrupt return to base

line

b) BBV: Normal

c) Initial acceleration

d) Secondary

acceleration

Non-reassuring(atypical)

a) Slow return to baseline

b) BBV: Loss during

deceleration

c) Loss of initial

acceleration

d) Persistent acceleration

after recovery

e) Continuation of base

line at low level

f) Biphasic deceleration

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Atypical variable deceleration

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4. Prolonged deceleration

Define:

Decrease in the FHR below the baseline

Deceleration is 15 bpm

lasting 2 min but < 10 min from onset to return

to baseline

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Prolonged deceleration

following uterine rupture

Prolonged deceleration

following vaginal exam

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Significance:

• Non-Reasurring: lasts between 2-3 min

• Abnormal: lasts longer than 3 min it is

immediately classed as Action must be taken

quickly

e.g. FB sampling/emergency CS

Maternal

1. Hypotension

2. Hypoxia

3. Uterine

hyperactivity

4. Abruption

5. Uterine rupture

Fetal

1. Hypoxia

2. Fetal hemorrhage

3. Cord prolapse

4. Cord compression

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Prolonged Decelerationeither Late or Variable

>90 sec & < 10 min,

Drop in FHR of 30 bpm or More

lasting for at least 2 m

Depth& duration

Correlate e Insult

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Abrupt decrease

>15 bpm

Often drops<100

>2 m & < 10 m

Variable pattern

{uterine hyperactivity}

Approximately 3 min

are shown but FHR

returned to normal

after uterine

hypertonus resolved.

Vaginal delivery later

ensued.

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Manual Compression of

a prolapsed umbilical cord

in a 25-w footling breech.

A. 25- sec compression

B. 40 sec compression

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Early DecelerationLate Deceleration

Variable Deceleration

Abrupt decrease

>15 bpm

Often drops<100

>15 S& < 2 m

Variable pattern

Abrupt decrease

>15 bpm

Often drops<100

>2 m & < 10 m

Variable pattern

Prolonged Deceleration

may drops<100Usually did not drops<100

Decelerations

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Thanks

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