INTRAPARTUM FETAL MONITORING
Dr Manal Behery
Professor OB&GYNE
2014
Methods available for fetal monitering
in labor
Intermittent auscultation
CTG Fetal electrocardiography
Scalp stimulation
Vibroacoustic stimulation
Fetal scalp sampling PH determination
Fetal pulse oximetry
Types of Intermittent
Monitors
Intermittent Auscultation
The three unique risk factors for fetus
during labor
Factor of uterine contraction
Factor of cord accident
Factor of head compression
Factor of uterine contraction
Oxy –Hb 0.19 micromol/100Gm of brain
Cerebral O2 saturation 9%
•
In spite of this slightly worrying picture, Nothing
harmful effect happen if
fetus is healthy
labor contraction are normal
Placenta has adequate reserve
Factor of head compression
Some degree of compression is inevitable during normal labor
But
Excessive compression over long period causing
supermoulding as in obstructed labor may cause fetal hypoxia
Factor of cord accident
Only during labor cord prolapse ,presentation and
entanglements become apparent either by compression or
stretch secondary to uterine contraction
Aim of intrapertum fetal monitering
1- to detect the earliest stages of hypoxia so therapy
can be directed to prevent asphyxia and asphyxial
damage( e.g Cerebral palsy)
2-To Improve perinatal morbidity & mortality
What is Cardiotocography(CTG)?
It is a paper record of the continuous FHR blotted
simultaneously with a record of uterine activity
Ultrasound (cardio) transducer
Tocotransducer
CTG reCords
Non stress test
without uterine contraction
Stress test
in correlation to uterine contraction
External monitoring
Internal monitoring
Intrapartum Fetal monitoring CTG
FHR trace(4 components)
Base line FHR
Baseline variability
Accelerations
Decelerations
Baseline FHR
The dominant reading taken ≥10 min
Normal baseline FHR 110-160(pbm)
Controlled by atrial pacemaker
Baseline FHR
Tachycardia FHR>160 bpm
Baseline bradycardia FHR<110bpm
Baseline varibility
The Oscaltatory pattern of FHR when recorded on a graph.
Short term(beat t0 beat)
is the fluctuation of HR over short interval
Long term
is the fluctuation over long interval(≥2 min)
Indicates mature fetal neurologic system
Baseline varibility
Short term variability
(scalp electrode)
Long term variability
defined as 3-5 cycle/min
Baseline varibility
No variability (0-2 ครั้ง/นาที)
Minimal variability (3-4 ครั้ง/นาที)
Moderate variability (11-25
ครั้ง/นาที)
Mark variability (>25 ครั้ง/นาที)
Accelaration
Increase in FHR with contraction or with other activities
Increase15pbm
lasting 15 sec
Return to base line <2 min
Accelaration
Decelerations
Decelerations
Transient slowing of FHR below
The baseline level> 15 bpm
and lasting for 15 sec.
or more.
Early Decelerations
Uniform
Synchronous with contraction (mirror image)
Rarely fall below 110 (pbm)
Due to head compression
Should not be disregarded
if they appear early in labor or Antenatal.
Early Decelerations
Late Deceleration
Uniform
Start after peak of contraction
Associated with decreased
Variability
Reflect a baroreceptor
response
Indicate fetal hypoxia
Late Deceleration
Repetitive late decelration
increases risk of
Umbilical artery acidosis
Apgar score < 7 at 5 ms
Cerebral palsy
If associated with
decrease or loss of
variability
Variable Deceleration (the most
common type)
Varible in appearance and Timing.
May be assoicated with increased variability .
Reflect umbilical cord compression
• Of no clinical significance if non recurrent
.
Variable Deceleration
Tyes of decleration
Prolonged Deceleration
deceleration
A deceleration that lasts more than 90
seconds (but less than 10 minutes)
Drop in FHR of 30 bpm or More
Reduction in O2 transfer to placenta.
Associated with poor neonatal outcome
Prolonged Deceleration
What are the features of a normal
tracing?
Baseline FHR 110-160 BPM
Baseline Variability > 5 pbm (10-25)
2 Accelerations > 15 BPM > 15 sec / 20 min trace
No decelrations
Normal -Reassuring CTG
Interpertation of CTG
Normal -Reassuring(R)- CTG with all 4
Features
Suspicious (equivocal)- one non reassuring
category and reminder are reassuring
Abnormsal -Non reasurring (NR) - 2 or
more non-reassuring categories or one or
more abnormal categories.
Interpertation of CTG
Consider
Intrapartum / antepartum trace.
Stage of labour
Gestation
Fetal presentation.
Any augmentation
Medications
Is Normal CTGs always Reassuring?
With normal CTC the chance of fetus to develop hypoxia is
1.5% due to unpredictable acute events
So a normal CTG is always Reassuring
Is NR CTGs always worrisome ?
60% CTG in Labour have 1 abnormal feature
Only 15-20% of NR CTGs are pathological.
High false positive rate with unnecessary operative
intervention for fetal distress.
Thus NR CTG is not always worrisome.
?? To reduce CS….
Consider these factors with abnormal
CTG
Maturity of the fetus
Reduced variability and baseline tachycardia is conmen in
preterm
State of maternal pulse
Drugs may cause maternal and fetal tachycaedia
Check blood pressure for hypotension in patients on
epidural.
Consider these factors with abnormal
CTG
Posture of patient during CTG
o Supine position give abnormal tracing
o Some cord compression can get released by change
posture and must be tried with variable deceleration
Congenital fetal malformation
Color Doppler of fetal heart to exclude congenital heart block
Correct reversible causes
Change mother position from supine to left lateral
position-----increase uterine blood flow
Improve maternal oxygenation—100% O2 by masK
Correct maternal hypotension –IV fluid
Decrease or stop any oxytocin infusion
Remove vaginal prostaglandins
Secondary tests of fetal well-being
Vibro-acoustic stimulation
Used as a substitute for scalp sampling when CTG –is NR
Normal ----------if FHR acceleration > 15 bpm for 15
seconds within 15 seconds after the stimulation with
prolonged fetal movements.
Abnormal ----Only 50% have acidotic PH
Fetal blood sampling
If the pH >7.25 --- observe.
If the pH 7.2 and 7.25---repeated
within 30 minutes.
If the pH <7.2----repeat immediately
If pH still low -- Prompt delivery
Scalp stimulation.
Firm digital pressure
Gentile pinch by atramatic Allis forceps
Fetal pulse oximetry.
THANK YOU
