undergraduate course lectures in Obstetrics&Gynecology, Faculty of medicine,Zagazig University

1. INTRAPARTUM FETAL MONITORING
DR MANAL BEHERY
Zagazig University, EGYPT

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

12. External monitoring
Doppler ultrasound transducer
FHR
Tocotransducer(contraction)

13. Internal monitoring

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

17. Tachycardia FHR>160 bpm

18. Baseline bradycardia FHR<110bpm

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

20. Baseline varibility
Short term variability
(scalp electrode)
Long term variability
 defined as 3-5 cycle/min

21. Baseline varibility

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

25. Accelaration

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.

28. Early Decelerations

29. Late Deceleration
Uniform
Start after peak of contraction
Associated with decreased
Variability
Reflect a baroreceptor
response
Indicate fetal hypoxia

30. Late Deceleration

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
.

33. Variable Deceleration

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

35. Prolonged Deceleration

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)

37. Sinusoidal pattern

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

39. Normal -Reassuring CTG

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.

43. ?? To reduce CS….

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

50. Scalp stimulation.
Firm digital pressure
Gentile pinch by atramatic Allis forceps
Fetal pulse oximetry.