This document provides information on antepartum and intrapartum fetal surveillance. It discusses various testing modalities used in antepartum surveillance such as fetal movement counting, non-stress testing, biophysical profile, and Doppler velocimetry. It also describes parameters assessed in intrapartum surveillance including fetal heart rate monitoring patterns such as baseline rate, variability, accelerations, and decelerations. The goal of both antepartum and intrapartum surveillance is to detect fetal hypoxia and intervene early to prevent injury or death.

1. Antepartum and intrapartum
fetal surveillance
Ambo University, CMHS
For 3rd year HO students
Dr. Rabirra Waktola
June 2020

2. Contents
Antepartum fetal surveillance
 Definition
 Indications
 Testing/surveillance modalities
Intrapartum fetal surveillance
 Definition
 Parameters for intrapartum fetal surveillance
2

3. Objectives
to know some modalities of antepartum and
intrapartum surveillance
to have basic understanding on how to
do/when to do commonly used fetal
surveillance
to know how to interpret the results of the
fetal surveillance
3

4. Antepartum fetal surveillance
4

5. Definition
Assessment of the wellbeing of the
fetus/fetuses during pregnancy especially
after the fetus is considered viable
The goal is to identify those fetuses at risk
of intra uterine neurologic injury or death so
that these adverse outcomes can be
prevented.
5

6. Rationale
Fetal hypoxia and acidosis represent the
final common pathway to fetal injury and
death
Fetus with hypoxia will respond in a series
of detectable physiologically adaptive or
decompensatory signs
6

7. Indications
Uteroplacental insufficiency
 post term, suspected IUGR, DM, hypertension,
multiple pregnancy, previous still birth
Fetal compromise by other test
 Decreased fetal movement, Oligohydraminos
Routine surveillance
7

8. Testing modalities
Fetal movement count
Non stress testing
Contraction stress testing
Biophysical profile
Doppler velocimetry
8

9. 1. Fetal movement count
Fetal movements are first perceived by the
mother at 17-20 weeks and becomes more
sophisticated and complicated by the end of
pregnancy
The logic behind fetal movement testing is
that fetal movements decrease in response
to hypoxia
9

10. Mother appreciate 80% of fetal movement,
but beyond 36 weeks only 16% of
movements are perceived by the mother
An important determinant of fetal activity is
sleep-wake cycle
Sleep cyclicity varies from as low as 20 to
as much as 75 minutes
10

11. Methods of FM counting
1.The Cardiff method
<10 movement over 12 hours is alarming
NB:we usually use this method in our wards in admitted patients and
there should be at least 10 movements in 12 hr duration
2.Sadovsky method
-mother count FM 3x daily each for 30min –
-normal is more than 4 movements
-<3 movement/one hour is alarming
3. Rayburn method
- count once per day for 60minutes between 7 and
11 PM after dinner
-normal is more than 4 movements
- <3 movement/1hr for two consecutive days is
alarming
11

12. Factor that decrease FM
Placental location
Length of fetal movement
Amniotic fluid volume
Fetal anomalies
Fetal state (if sleeping or not)
Maternal activity
Obesity
Medication use
Fetal jeopardy
12

13. 2. Non stress testing
Almost all fetal movement (85-90%) are
accompanied by acceleration of FHR in
normal fetus
Acceleration
 If G.A >32 weeks the peak of acceleration is 15 beats per
minute or more above the baseline fetal heart rate but
acceleration last 15 seconds or more but less than 2 minutes
 If G.A< 32 weeks accelerations are defined as having peak
10 beats per minute or more above the baseline for 10
seconds or longer
13

14. Technique (it needs cardiotocography)
 Mother in left lateral position and continuous
electronic fetal heart monitoring conducted for
40 minutes.
 Mother provided with indicator to press
whenever she feels fetal movements.
 Tracing of fetal heart pattern made throughout
and checked for alterations associated with fetal
movement.
14

15. Interpretation
Reactive Non Stress Test
 Two or more accelerations that peak at 15 bpm or more
above the baseline each lasting 15 seconds or more,
within 20 minutes, with or without fetal movement
discernible by the mother
Non Reactive Non Stress Test
 Lacks sufficient fetal heart rate acceleration over a 40
minutes period
15

16. Factors causing Non-reactivity
Fetal sleep
Fetal anomalies-Neurologic/Cardiac
CNS depressants
Beta-blockers
Maternal smoking
Prematurity
Sepsis
Fetal jeopardy
16

17. 3. Contraction stress test
The premises behind CST is that uterine
contractions transiently restrict oxygen
delivery to the fetus and hypoxic fetus will
demonstrate recurrent late decelerations
There are two methods of contraction stress
test
 Intravenous oxytocin
 Nipple stimulation
• NB:Read the intapartal fetal surveillance part of this slide
for the definition of decelerations 17

18. Fetal heart rate and uterine contraction are
recorded simultaneously with an external
monitor (cardiotocography or CTG)
18

19. Contraindication of CST
Patient at high risk for premature labor
- Premature ROM
- Multiple gestation
- Cervical incompetence
Condition in which uterine contraction is
dangerous
- Placenta previa
- Previous classical C/S
- Previous uterine surgery 19

20. Interpretation
 Negative -80% of test
 No late deceleration appearing anywhere on the
tracing with adequate uterine contraction (3
contraction in 10 min, lasting for 40-60sec)
 Negative means the fetal condition is good
 Positive -3-5% of test
 Late deceleration that are consistent and persistent
and occurring in at least >50% of contraction
without excessive uterine contraction
20

21. Suspicious (equivocal) -5% of tests
 Inconsistent late deceleration
Hyperstimulated -5% of cases
 Uterine contraction closer than every 2min or lasting
for >90sec
Unsatisfactory- 5% of cases
 Quality of tracing is inadequate for interpretation or
adequate uterine contraction can not be achieved
21

22. 4. Biophysical profile
Components
1.Non stress test
2.Fetal breathing movements
3.Fetal movements
4.Fetal tone
5. Determination of the amniotic fluid volume
Other than non stress test the other components (2-5)
needs ultrasound
22

23. 23

24.  Those fetal biophysical activities that
appear earliest in fetal developments are the
last to disappear with fetal hypoxia
 Fetal tone, fetal movement, fetal breathing
and FHR control develop in this sequence
 So, NST and FBM are the two parameter
that are affected initially
24

25. Interpretation
BPP of 10/10 OR 8/10 with normal AFV(amniotic fluid
volume) OR 8/8 NST not done
 Reassuring BPP, non asphyxiated fetus
 repeat test weekly (twice weekly in diabetes and post term)
BPP of 8/10 with abnormal AFV
- Have risk of chronic asphyxia
- Terminate pregnancy if term and
oligohydramnios
- Repeat test 1-2xweekly if not term
BPP of 6/10
- Possible fetal Asphyxia, terminate if term
- Repeat test after 4-6hour , deliver if <6
25

26. BPP of 4/10
 probable fetal asphyxia
 repeat the test after 4-6 hour , deliver if <6
BPP of 0-2/10
 Almost certain fetal asphyxia
 Deliver
26

27. Modified Biophysical Profile (NST + AFI)
Modified BPP combines the NST(with the
option of VAS) as a short term indicator of
fetal acid-base status and AFI as an
indicator of long term placental function
Modified BPP considered normal if NST is
reactive and AFI is more than 5cm
VAS-vibroacoustic stimulation 27

28. 5. Doppler velocimetry
Doppler ultrasound is non invasive method to
assess blood flow
Umbilical artery, middle cerebral artery and ductus
venosus can be assessed by Doppler
Umbilical artery systolic/diastolic ratio is
commonly used
Abnormal result when
- if S/D ratio is above 95th percentile
- Absent diastolic flow
- Reversed diastolic flow
Usually employed in case of IUGR
28

29. Rate of still birth with reassuring result over 1wk
• Reactive NST-5/1000 live births
• Negative CST- 1-2/1000 live births
• BPP-1.9/1000
• Commonest cause of still birth following reassuring
result
- Erratic blood sugar level in diabetic
- Abruptio placenta
- Cord accident
- Fetal malformation

30. Algorithm for the tests
• NST
Reactive Non reactive
Retest CST Positive
Negative BPP
Retest in 24 hour consider
delivery if
abnormal

31. summary
Timing of initiation of test
• Most start at 28-32 weeks of gestaion
• Earlier initiation if risks are identified
Frequency of test
• On weekly basis for routine testing
• Twice weekly in case – severe preeclampsia
- post term pregancy
- Rh issoimunization
- Uncontrolled DM
- IUGR

32. Intrapartum fetal surveillance
32

33. Goal is to detect
fetal hypoxia and
take measure
If metabolic acidosis
ensues intervene
early before it result
in tissue
damage/death
33
Tissue damage & Death
Acidosis
Hypoxia
Normal Oxygenation

34. Fetal defense mechanisms against asphyxia
34
Hemoglobin F-
higher oxygen
affinity
Large placental
surface area for
exchange with
sufficient reserve-
nearly 11 meters
square
Low fetal partial
pressure of oxygen
creating a large
diffusion gradient-
30 mmH2O
Special fetal
circulation with
preferential flow of
oxygenated blood to
vital organs
Large uterine blood
flow with sufficient
reserve

35. Parameters used in assessing
intrapartum fetal well being
Fetal heart beat monitoring
Meconium staining of amniotic fluid
Fetal scalp blood sampling
Umbilical cord blood sampling
35

36. Risk factors for intrapartum asphyxia
Majority- cannot be predicted or are not
associated with the known risk factors
Pregnancies known to be associated with a
higher risk of intrapartum asphyxia and
require increased vigilance include
36

37. 37

38. 1. FHR monitoring
FHR monitoring in real sense is fetal brain
monitoring
Fetal brain responds to hypoxia by altering
FHR(fetal heart rate)
38

39. Methods of monitoring FHR
Intermittent auscultation
 Pinnard stethoscope/fetoscope
 Doppler US device
Continuous fetal heart monitoring
 Electronic fetal heart monitoring (cardiotocography)
39

40. Doppler US device
40
Pinnard stethoscope

41. Intermittent auscultation
Auscultation for period of 60sec following contraction
In high risk
 Every 15 min in 1st stage
 Every 5 min in 2nd stage
In low risk
 Every 30 min in 1st stage
 Every 15 min in 2nd stage
Advantage: Available, easy to use, inexpensive and
effective if done in consistent manner
Disadvantage: Labor intensive’ may not detect some
abnormal FHR patterns, sometimes difficult (obesity)
41

42. Electronic fetal monitoring (CTG)
Continuous recording & graphical
representation of FHR & uterine
contractions
EFM-can either be performed externally or
internally
42

43. External EFM
FHR
 Doppler US signal Microprocessor  Converted
to FHR
Uterine contraction
 Tocodynamometer  Ux contraction Change in
shape and rigidity  Depresses the plunger of the
sensor
43

44. 44

45. Internal EFM
FHR
- Spiral electrode are applied directly to the fetal scalp
- Fetal ECG RR interval processed into FHR or ST
segment analysis
Uterine contraction
- Intra uterine pressure catheters are inserted trans
cervically beyond and above the presenting part
45

46. FHR pattern
Full description of a FHR tracing requires a
qualitative and quantitative description of
A. Base line heart rate
B. Base line FHR variability
C. Periodic changes
A. Presence of accelerations
B. Periodic or episodic decelerations
D. Changes or trends of FHR patterns over time
46

47. A.Base line FHR
Base line FHR - is the approximate mean
FHR during a 10 minute segment
 Normal: 120-159 beats per minute (bpm)
 Tachycardia - baseline rate above 160 bpm
- Mild 160-180bpm
- Severe ≥ 181
 Brady cardia-
 Base line FHR < 120 bpm
 mild 100-119bpm
 moderate 80-100bpm
 severe<80bpm
47

48. Fetal tachycardia
48
>160
BPM
Most are
not
suggestive
of fetal
jeopardy
Associated
with
 Fetal hypoxia
 Maternal fever
 Hyperthyroidism
 Maternal or fetal
anemia
 Drugs:Atropine
 Chorioamnionitis
 Fetal tachyarrhythmia
 Prematurity

49. Fetal bradycardia causes
Maternal hypothermia
Complete heart block
Severe asphyxia
49

50. B) Baseline Beat-to-beat variability
is the difference in heart rate from one beat
to the next
important index of cardiovascular function
and appears to be regulated largely by the
autonomic nervous system
50

51. Beat-to-beat variability
51

52. 52

53. Causes of decreased/absent variability
 Hypoxia and acidosis
 Fetal anomalies
 Tachycardia
 Extreme prematurity
 Previous neurologic insult
 Fetal sleep cycles
 Drugs (CNS depressants)
53

54. C) Periodic changes
changes of FHR for brief duration with return to
baseline in response and relation to contraction
Decelerations (Early, late, variable, prolonged)
Accelerations
54

55. Acceleration
An abrupt increase in the FHR.
 Before 32 weeks of gestation, accelerations should last
≥10 sec and peak ≥10 bpm above baseline.
 After 32 weeks gestation, accelerations should
last ≥15 sec and peak ≥15 bpm above baseline.
A prolonged acceleration is ≥2 minutes but less
than 10 minutes. An acceleration of 10 minutes or
more is considered a change in baseline
Physiologic response to fetal movement
55

56. 56

57. Decelerations (decrease in heart rate)
Early Decelerations
Late Decelerations
Variable Decelerations
prolonged Decelerations
57

58. Early Decelerations
A gradual decrease and return to baseline of the
FHR associated with a uterine contraction
The nadir of the FHR and the peak of the
contraction occur at the same time
Caused by fetal head compression during uterine
contraction, resulting in vagal stimulation and
slowing of the heart rate
not associated with fetal distress and thus are
reassuring
58

59. 59

60. Late Decelerations
A gradual decrease and return to baseline of
the FHR associated with a uterine
contraction
The deceleration is delayed in timing, with
the nadir of the deceleration occurring after
the peak of the contraction
The onset, nadir, and recovery usually occur
after the onset, peak, and termination of a
contraction 60

61. Always indicate fetal hypoxia 2ndry to
uteroplacental insufficiency
 Hyper-stimulation
 Micro vascular diseases (poor perfusion of
uteroplacental vascular bed)
 Abruptio placenta
 Maternal hypotension
61

62. Late deceleration
62

63. Variable deceleration
Variable in size, shape and timing in
relation to contraction
Abrupt and sharp onset and return
Indicative of cord compression
 occult cord prolapse
 Cord presentation
 True cord prolapse
63

64. 64

65. Prolonged deceleration
Lasts 2min-10min
Cause can be any of the mechanisms
previously described
65

66. D) Sinusoidal pattern
visually apparent, smooth, sine wave-like
undulating pattern in FHR baseline with a
cycle frequency of 3-5 per minute lasting
for 20 minutes or more
Rare but significant
True sinusoidal pattern is associated with
fetal anemia
 Isoimmunization
 ruptured vasa previa
 feto-maternal hemorrhage

67. 67

68. Standards for interpretation
3 categories
I. A reassuring fetal heart rate pattern (category I)
II. Indeterminate patterns (category II)
III.Nonreassuring tracings (category III)
68

69. Reassuring fetal heart rate pattern (category I)
A baseline fetal heart rate of 110 to 160
bpm
Absence of late or variable FHR
decelerations
Moderate FHR variability (6 to 25 bpm)
Age appropriate FHR accelerations
69

70. Indeterminate patterns (category II)
Tachycardia(not the persistent one)
Minimal or marked variability
absent variability without recurrent
decelerations,
absence of accelerations without absent
variability,
recurrent late or variable decelerations
without absent variability
prolonged deceleration
70

71. Nonreassuring tracings (category III)
Absent or minimal variability with
decelerations or bradycardia
Recurrent late deceleration
Recurrent late deceleration
Bradycardia
Sinusoidal heart rate pattern
71

72. 2. Meconium staining of amniotic fluid
Hypoxic insult – vagal response –
meconium passage
Can occur in absence of significant or
sustained hypoxia
Has 3 grades
 Grade I-lightly meconium stained
 Grade II-between grade I and II
 Grade III-stained doughy thick meconium
72

73. 3. Fetal scalp blood sampling
not of much practical significance in the
diagnosis of fetal asphyxia
Fetal scalp blood pH<7.2 indicates acidosis
where >/=7.2 is normal
73

74. 4. Umbilical cord blood sampling
After delivery a sample of cord blood is
taken and analyzed for Po2, PCO2 and PH,
HCO= .
Useful to assess presence of asphyxia
retrospectively and also manage the neonate
74

75. Management of a non-reassuring fetal status
75
Resuscitation Definitive treatment
•Put the mother in the left lateral
position
•Oxygen by face mask at a rate of
5L/min
•Rehydrate with IV fluids
•Discontinue oxytocin
•Amnioinfusion – warm saline into the
uterine cavity through the intrauterine
catheter
•Tocolysis if hypertonus is diagnosed
•Monitor FHR further and observe for
improvements
•Expedited delivery depending on the
stage of labor
•Instrumental delivery
•Caesarean delivery
•Breech Extraction

76. 76