This document discusses fetal monitoring techniques during labor and delivery. It notes that electronic fetal monitoring (EFM) is associated with decreased mortality but increased cesarean rates compared to auscultation. The document then focuses on fetal ST analysis (STAN), which analyzes changes in the fetal ECG that indicate hypoxia. Studies in the UK and Sweden found that combining EFM with STAN reduced metabolic acidosis in umbilical cord blood gases and lowered operative delivery rates compared to EFM alone. STAN provides a more precise assessment of fetal condition during labor to guide management and avoid unnecessary interventions.

1. Presented By:
Chukwuma I. Onyeije, M.D.
Atlanta Perinatal Associates
Clinical Associate Professor,
Morehouse School of Medicine

3. Specific FHR abnormalities
are related to cerebral palsy
and neurologic injury in the
fetus

8. The 1970s
CLINICAL OBSTETRICS AND GYNECOLOGY
Volume 54, Number 1, 56–65
r 2011, Lippincott Williams & Wilkins

10. Intrapartum EFM associated
with decreased perinatal
mortality due to fetal hypoxia
but also with higher rates of
surgical intervention for
suspected fetal distress.
Vintzeleos et al, Obstet Gynecol. 1993 Jun;81(6):899-907.

11. Compared to
Auscultation, EFM
results in higher
operative delivery rates
without significant
lowering of perinatal
mortality.

12. Conclusion:
Auscultation…. The winner!

14. Scalp pH  Pulse Oximetry

15.  Scalp pH largely abandoned in the United
States 2 decades ago.
 Fetal pulse oximetry did NOT reduce
cesarean delivery rates for ‘nonreassuring’’ FHR
patterns in NICHD trial.

17.  The fetal ST interval changes in the fetus suffering
from oxygen deficiency.
 ST Analysis (STAN) consists of highlighting
theses changes.

18. For a fetus, the birth is the treadmill.

20.  STAN begins with conventional EFM (FHR +
UCs) and adds automated ST Analysis
 Comprehensive and mandatory education prior
to introduction of STAN

22. Showed that hypoxia
was associated with a
significant elevation of
the T-wave in the
fECG.
Am J Obstet Gynecol.
1984;149:190–195.

23.  Increased myocardial glycogen
breakdown
 Liberation of potassium
 Increased local catecholamines

24.  The increase in T-wave height relative to the
amplitude of the QRS complex was identified
when the fetus transitions from aerobic to
anaerobic metabolism.

29.  The T:QRS ratio measures of myocardial
metabolic status
 Other changes in the ST-segment identified
fetuses with chronic oxygen deprivation were
subjected to acute hypoxic stress.

31. Baseline T :QRS ratio
Appearance of ST segment
waveforms

32.  Hypoxic fetuses
 Fetuses with
myocardial
dysfunction
 Chronically hypoxic
fetuses with acute
insults

33. BEFORE using STAN
 >36+0 gestational weeks
 Ruptured membranes
 No contraindication for scalp electrode or STAN
 First stage, no active or involuntary pushing

34. At onset of STAN
 Classify the FHR.
 Check for FHR reactivity
 Confirm nondeteriorating fetal state
 Check for normal ECGwaveform
 Confirm sufficient signal quality
 Confirm baseline T:QRS ratio

35.  Any contraindication to
invasive monitoring
◦ active maternal herpes
◦ HIV
◦ Hepatitis

36. STAN
determines baseline
T:QRS ratio over
20 T :QRS ratios
and then tracks for
changes over
time.

37. T:QRS Ratio
EVENT LOG
AVERAGE T:QRS
ST ALRETS

38.  Episodic rise in T:QRS ratio
◦ (greater than 0.10 for less than 10 min);
 Baseline rise in T :QRS ratio
◦ (greater than 0.05 for more than 10 min); and
 Recurrent biphasic ST segments

42. FHR
CLASSIFICATIO
N
BASELINE FHR VARIABILITY DECELERTION
S
GREEN
110 - 160 MODERATE
(+)ACCELERATIONS
EARLY
VARIABLE (LESS
THAN 60 x 60)
YELLO
W
BRADY <110
TACHY > 160
> 150 WITH
MINIMAL
VARIABILITY
MINIMAL FOR
> 40 MIN
MARKED FOR
> 40 MIN
VARIABLE
GREATER THAN
60 x 60
RECURRENT
LATE
PROLONGED
RED SINUSOIDAL OR ABSENT VARIABILITY REGARDLESS
OF FHR PATTERN

43. STAN’s FHR Clinical
Management Protocol
FHR CLASSIFICATION NO ST EVENTS ST EVENTS
PRESENT
GREEN EXPECTANT MANAGEMENT
CONTINUED OBSERVATION
YELLOW
EXPECTANT
MANAGEMENT
DIRECT PHYSICIAN
ASSESSMENT OF
FETAL STATE IF > 60
MINUTES
DIRECT PHYSICIAN
ASSESSMENT
INTRAUTERINE
RESUSCITATION
EXPEDITED DELIVERY
IF NO IMPROVEMENT
RED EXPEDITIOUS
DELIVERY / RESUSCITATION (?)

45.  Main outcome of interest was a reduction in
cord artery metabolic acidosis (pH <7.05
and base deficit >12 mmol/L) with the addition of
STAN data.
U.K. – Am J Obstet Gynecol. 1993;169:1151–1160.
Sweden - Lancet. 2001;358:534–538.

46. UNITED KINGDOM: 1993 SWEDEN: 2001

47.  Significant reduction in fetal metabolic acidosis
AND reduction in operative delivery.
 Follow-up studies of the neonates showed a
significant reduction in neonatal encephalopathy

48.  Standard EFM is very good at
detecting the very healthy and very
sick fetus.
 STAN allows us to grade fetuses
between the extremes

49.  STAN combined with EFM provides more
accurate information about the fetus during labor
than EFM alone.
 STAN is automatic, continuous and has been
proven to be effective in large randomized trials.

50.  Information from STAN provides precise
information about the fetal state during labor to
detect fetuses at risk and avoid unnecessary
interventions.

51.  CLINICAL OBSTETRICS AND GYNECOLOGY Vol.54, Number 1, 56–65. 2011,
 Am J Obstet Gynecol. 1993;169:1151–1160.
 Lancet. 2001;358:534–538.
 Am J Obstet Gynecol.1984;149:190–195.
 Obstet Gynecol. 1993 Jun;81(6):899-907
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