2. The three unique risk factors for fetus
during labor
Factor of uterine contraction
Factor of cord accident
Factor of head compression
3. Factor of uterine contraction
Let us see what happen to oxygenation
and blood supply of the fetal brain during
a uterine contraction?
4. De-oxy-Hb 0.79micromol/100Gm of brain
Oxy –Hb 0.19 0.79micromol/100Gm of brain
CerebralO2 saturation 9%
Cerebral blood volume 0.33 ml/100Gm of
In spite of this slightly worrying picture,
Nothing harmful effect happen if
fetus is healthy
labor contraction are normal
Placenta has adequate reserve
5. Fetal distress, birth asphxia are likely
to occur if
The fetus is already compromised
antenatally---even with normal uterine
contraction
The uterine contraction are
exaggerated------even with healthy
fetus and adequate placental reserve
6. Factor of cord accident
Only during labor cord prolaps ,presentation
and entanglements (occult or overt) become
apparent either by compression or stretch
secondary to uterine contraction
7. 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
8. Methods available for fetal monitering
in labor
Intermittent auscultation
CTG Fetal electrocardiography
Scalp stimulation
Vibroacoustic stimulation
Fetal scalp sampling PH determination
Fetal pulse oximetry
9. Important definations
Hypoxia: Decreased po2 level in tissues.
Hypoxima: Decreased po2 level in blood.
Acidosis: Decreased PH in tissues.
Acidemia: Decreased PH in blood.
Ashyxia: Hypoxia with acidosis.
10. Aim of intrapertum fetal monitering
1- to detect the earliest stages of hypoxia or
(hypoxic acidemia ) so therapy can be
directed to prevent asphyxia and asphyxial
damage
2-To Improve perinatal morbidity &
mortality
11. 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
14. What is ‘’Admission test ‘’?
Ideally every fetus every fetus should be screened by
CTG for a short period (20 min) right on admission
in labor.
From nature of the trace determine
Intensity of monitoring “Whether the case
should be monitored clinically or by CTG”
Duration and frequency of monitoring
“Whether the case should be covered by CTG
continuously or intermittently”
15. Interpreting FHR trace
4 components
Base line FHR
Baseline variability
Accelerations
Decelerations
16. Baseline FHR
The dominant reading taken ≥10 min
Normal baseline FHR 110-160(pbm)
Controlled by
atrial
pacemaker
19. 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
22. No variability (0-2 ครั้ง/นาที)
Minimal variability (3-4 ครั้ง/นาที)
Moderate variability (11-25
ครั้ง/นาที)
Mark variability (>25 ครั้ง/นาที)
23. Changes in fetal HR
Peroidic changes: Occur with
contraction
Episodic changes (non peroidic):do not
occur with contraction
24. Accelaration
Increase in FHR with contraction or
with other activities
Can be periodic or episodic
Increase15pbm
lasting 15 sec
Return to base line <2 min
26. Decelerations
Decelerations
Transient slowing of
FHR below the
baseline level
more than 15 bpm
and lasting for 15 sec.
or more.
27. 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.
31. 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
32. Variable Deceleration (the most
common type)
Varible in appearance and Timing.
May be assoicated with
increased variability .
Reflect umbilical cord compres
Observed in up to 50% of NSTs compression
• Of no clinical significance
if non recurrent
.
34. 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
36. Sinusoidal pattern
Regular Oscillation of the Baseline long-term
Variability resembling a Sine wave ,with no beat
to -beat Variability.
Has fixed cycle of 3-5 pbm with amplitude of 5-15
bpm and above but not below the baseline.
Should be viewed with suspicion as poor outcome
has been seen (eg Feto-maternal haemorrhage)
38. 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
40. 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.
41. 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
42. 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.
44. Consider these factors with abnormal
CTG
Clinical indication of doing CTG
Abnormal patch of tracing from high risk case differ
that from no risk case
Maturity of the fetus
Reduced variability and baseline tachycardia is
conmen in preterm
State of maternal pulse
Drugs may cause maternal tachycardia– fetal
tachycaedia
Check blood pressure for hypotension in patients
on Epidural
45. 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
Stage of labor and expected time of
delivery Wether to deliver immediate or give
sometime under close observation
46. Suspicious (Equivocal)CTG
Do continuous monitoring for further
development towards better or worse trace
while instituting the corrective measures.
Ideally check condition of fetus by FAS or
FBS or scalp stimulation test.
However ,if liquor is meconium stained
---Deliver immediately
47. 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
48. 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
49. 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