This document provides information on intrapartum fetal monitoring techniques including fetal heart rate monitoring, indications for continuous electronic fetal monitoring, interpretation of fetal heart rate patterns, and management of non-reassuring fetal status. It discusses techniques like intermittent auscultation, electronic fetal monitoring, fetal scalp pH testing, pulse oximetry, and lactate testing. The goal of intrapartum monitoring is timely identification and rescue of fetuses at risk for neonatal morbidity from hypoxic insult during labor and delivery.
6. TECHNICAL CONSIDERATIONS
Basis for FHR monitoring is beat to beat recording
For practical purposes ,this is possible only when
direct fetal electrocardiograms are recorded with a
scalp electrode.
Paper speed is important. Commonly used are 1,2 or 3
cm/min.
1 cm/min –a) good records for clinical purposes and
limiting the cost and amount of paper
b)crowding together of the record making
baseline variability difficult to interpret.
7. Contd…
3 cm/min- a) useful when record is difficult to
interpret at slow speed i.e. during second stage of
labor
b) waste of paper more
8. Internal FHR monitoring Spiral electrode attatched to the fetal scalp with a
connection to FHR monitor.
The fetal membranes must be ruptured, and the cervix
must be at least partially dilated before the electrode
may be placed on the fetal scalp.
9. Intermittent auscultation
In uncomplicated pregnancies .
Doppler better than stethoscope.
Every 15 - 30 minutes in active phase of first stage and every 5
minutes in second stage
Listen in the absence of active pushing and toward the end of the
contraction and at least for 30seconds after each contraction
ACOG JUlY 2009
CONTINUOUS EFM
No benefit in low risk
Continuous EFM -when risk factors for present
Every 15 minutes in first stage and every 5 minutes during the
second stage.
10. Fetal Assessment : IA & EFM
Surveillence
Low-Risk
High-Risk
Pregnancies Pregnancies
Acceptable methods
Intermittent Auscultation*
Yes
Yes (a)
Continuous Electronic Fetal
Monitoring (EFM)
Yes
Yes (b)
First-stage Labour
30 min
15 min (a,b)
Second –stage labour
15 min
5 min (a,c)
Evaluation Intervals
•a- before, during and especially after a contraction for 60 sec
•b- includes evaluation of tracing every 15 min
• c- evaluation of tracing every 5 min
(ACOG & AAP 2007)
12. Risk factors during labour Prolonged rupture of membranes (> 24 hours)
Meconium-stained or blood-stained liquor
Fetal bradycardia
Fetal tachycardia
Maternal pyrexia > 38 ˚C
Chorioamnionitis
Vaginal bleeding in labour
Prolonged active first stage of labour (> 12 hours regular
uterine contractions with cervical dilatation>3cm)
Prolonged second stage of labour .
13. Other indications
Any use of oxytocin whether for induction or for
augmentation of labour
Before and for at least 20 minutes after administration
of prostaglandin
Epidural analgesia (immediately after inserting an
epidural block)
14. Benefits of EFM over IA Reduced risk of neonatal seizures(RR 0.50)
No benefit over IA did not reduce perinatal mortality(RR, 0.85)
did not reduce the risk of cerebral palsy (RR, 1.74)
Risks of EFM High false-positive results.
Increased rates of surgical intervention
High interobserver and intraobserver variability
COCHRANE 2006
16. External fetal monitoring
BASELINE
The mean FHR rounded to increments of 5 bpm during a 10minute segment, excluding:
—Periodic or episodic changes
—Periods of marked FHR variability
—Segments of baseline that differ by more than 25 bpm
The baseline must be for a minimum of 2 minutes in any
10-minute segment
Normal : 110–160 bpm
Tachycardia: > 160 bpm
Bradycardia: <110 bpm
17. FETAL HEART RATE MONITORING
Baseline Variability
Fluctuations in the baseline FHR that are irregular in
amplitude and frequency
Visually quantitated as the amplitude of peak-totrough in bpm.
Absent—amplitude range undetectable
Minimal—0 to5 bpm
Moderate (normal) — 6to25 bpm
Marked—> 25 bpm
18. Short term variability – small changes in fetal beat to
beat intervals under physiological conditions
Long term variability- certain periodicity in the
direction and size of these changes causes oscillations
of fetal heart rate around mean level
In FHR tracings short term variability is superimposed
over long term variability as minimal deflexions, not
interpreted by naked eye, therefore in clinical practice
variability means long term variability
19. Long term variability characterized by – frequency and
amplitude
Frequency is difficult to assess correctly
Therefore , variability is usually quantitated by
amplitude of the oscillations around baseline heart
rate.
20.
21. The tracing shows an amplitude range of ~ 10
BPM (moderate variability ).
23. ACCELERATION
A visually apparent abrupt increase in the FHR
<32 weeks: >10 BPM above baseline for >10 sec
>32 weeks: >15 BPM above baseline for > 15 sec
Prolonged acceleration lasts >2 min but <10 min in
duration.
If an acceleration lasts 10 min or longer, it is a baseline
change
24. Early Deceleration
Symmetrical gradual decrease and return of the FHR
associated with a uterine contraction
The nadir of the deceleration occurs at the same time
as the peak of the contraction.
In most cases the onset, nadir, and recovery of the
deceleration are coincident with the beginning, peak,
and ending of the contraction, respectively
25. Caused by fetal head compression by
uterine cervix
Usually seen between 4 and 6 cm of
dilation
26. Late Deceleration
Symmetrical gradual decrease and return 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.
In most cases, the onset, nadir, and recovery of the
deceleration occur after the beginning, peak, and
ending of the contraction, respectively
28. Variable Deceleration
Visually apparent abrupt decrease in FHR
The decrease in FHR is ≥ 15 bpm , lasting ≥ 15 sec, and
<2 minutes in duration.
When variable decelerations are associated with
uterine contractions, their onset, depth, and duration
commonly vary with successive uterine contractions.
29. Caused by compression of the umbilical cord.
If appearing early in labour-often caused by
oligohydramnios
30. TYPES
Typical
Atypical
Loss of shoulders
Slow return to baseline
Prolonged secondary rise in baseline
Loss of variability during deceleration
Continuation at lower baseline
31. Classification of the severity of
variable deceleration
MILD-
Deceleration of a duration of <30sec , regardless of
depth
Deceleration not below 80bpm , regardless of
duration
MODERATE- Deceleration with a level <80bpm
SEVERE- Deceleration to a level <70bpm for >60sec
32. Prolonged Deceleration
Decrease from baseline that is 15 bpm or more, lasting
≥ 2 min but <10 min
If lasts 10 minutes or longer, it is a baseline change
Causes-prolonged cord compression,prolonged
uterine hyperstimulation,severe degree of
abruptio,eclamptic seizure,following conduction
anaesthesia
33. SINUSOIDAL PATTERN
Visually apparent, smooth, sine wave-like undulating
pattern in FHR baseline with a cycle frequency of 3–5
per minute which persists for 20 min or more.
Indicates
severe fetal anemia as occurs in
Rh isoimmunization
Feto maternal hemorrhage
Twin twin transfusion syndrome
severe hypoxia
35. Three-Tiered Fetal Heart Rate
Interpretation System
Category I- NORMAL acid base status
• Baseline rate: 110–160 bpm
• Moderate Baseline FHR variability
• No Late or variable decelerations
• Early decelerations:
• Accelerations:
Category II-INDETERMINATE not categorized as Category I or III.
Category III-ABNORMAL acid base status-Intervention
• Absent baseline FHR variability and any of the following:
—Recurrent late decelerations
—Recurrent variable decelerations
—Bradycardia
• Sinusoidal pattern
36.
37. RCOG CLASSIFICATION
BASELINE
VARIABILITY
DECELERATIO
N
REASSURING
110-160
≥ 5 bpm
None
NON
REASSURING
100-109
161-180
< 5 for ≥40 min
but <90 min
Early decel;
typical variable;
single prolonged
≤ 3min
ABNORMAL
<100
>180
sinusoidal ≥ 10
min
< 5 for ≥90 min
Late decel;
atypical variable;
single prolonged >
3min
ACCELERATIO
N
present
38. Ancillary tests that can aid in the management of
Category II or Category III FHR tracings Four techniques are available to stimulate the fetus:
1)fetal scalp sampling,
2) Allis clamp scalp stimulation,
3) vibroacoustic stimulation, and
4) digital scalp stimulation
39. A Cochrane review of three trials concluded that
manual fetal manipulation did not decrease NRFS and
it is not recommended.
Cochrane review of two trials concluded that antenatal
maternal glucose administration did not decrease the
incidence of NRFS and it is not recommended.
40. Standard interventions for NRFS Supplemental oxygen
Discontinuation of any labor stimulating agent
Changing maternal position
Resolution of maternal hypotension-hydration.
P/V to determine umbilical cord prolapse, rapid
cervical dilation, or descent of the fetal head,ARM
Assessment of uterine contraction .
Tocolytics-in tachysystole with associated FHR
changes.
When the FHR tracing includes recurrent variable
decelerations -Amnioinfusion
41.
42. MANAGMENT
Suspicious CTG If inadequate quality-check contact and connections
If hypercontractility-discontinue oxytocin, consider
tocolytics
Maternal tachycardia,pyrexia,dehydration, hypotension
Supine? Epidural? sedation? drugs?
i/v crystalloid bolus; 10 L/min O2
If persistent → do ancillary tests
Pathological CTG
FBS if feasible
If not feasible-expedite delivery (within 30 min)
43. Effects of Medications on FHR
Patterns
Narcotics decreased variability and accelerations
Corticosteroids Decreased variability (with beta-methasone but not dexamethasone)
Magnesium sulfate A significant decrease in short-term variability, clinically insignificant
decrease in FHR inhibits the increase in accelerations with advancing
gestational age
Epidural analgesia decreased variability and accelerations
Terbutaline Increase in baseline FHR
44. FETAL SCALP PH
In women with "abnormal“ fetal heart rate tracings .
Cervix needs to be 4-5cm dilated and Vx at -1 st or
below
pH <7.20 –fetal acidosis: deliver
pH 7.20-7.25 – borderline, repeat in 30 min or deliver if
rapid fall
pH > 7.25 – reassuring, repeat if FH abnormality
persists
Greater utility of scalp pH is in its high negative
predictive value (97–99%).
47. FETAL PULSE OXIMETRY
Acidosis: O2 sat. <30% for >2min
Approved by FDA for use in fetuses with NRFS in May
2000
The ACOG currently recommends against its use until
further studies are available to confirm its efficacy and
safety
Insufficient evidence for its use as an adjunct or
independent of electronic fetal surveillance.
48. FETAL SCALP LACTATE TESTING
Higher sensitivity and specificity than scalp pH
> 4.8 mmol/L : acidosis
Clinical trial that compared the use of scalp pH to
scalp lactate level did not demonstrate a difference in
the rate of acidemia at birth, Apgar scores, or neonatal
intensive care unit admissions
Not recommended for routine use
49. ST WAVEFORM ANALYSIS
Method: STAN S31 fetal heart monitor(USFDA)
Scalp electrodes
The electrical fetal cardiac signal – P wave, QRS
complex, and T wave – is amplified and fed into a
cardiotachometer for heart rate calculation
50. Restrict fetal ST waveform analysis to those with non
reassuring fetal status on EFM
The use of ST waveform analysis for the intrapartum
assessment of the compromised fetus is not recommended
for routine use at this time.