Describe Fetal Heart Rate Monitoring - ANSWER EFM may be external, internal or a com-
bination
In the US, the majority of women have EFM during some or all of their labors
Each modality has both pros and cons
Describe Doppler Ultrasound - ANSWER The doppler US transducer is used to assess FHR
characteristics and patterns. The transducer translates sound wave reflections into wave-
forms which are interpreted by a computer and then exported as an audible sound and a
waveform pattern.
Problems: FHR artifact, doubling, halving, and detection of maternal heart rate
Current ultrasound FHR signal processing uses autocorrelation techniques and interpretation
of EFM data is based on this assumption
Describe internal fetal electrode - ANSWER The FSE directly measures the FHR by meas-
uring R to R waves in successive QRS complexes. To place an FSE, adequate cervical dilation
(usually at least 2 cm) and ROM are needed.
Contraindications: placenta previa, hemophilia, maternal HIV, herpes infections, or when
presenting part is not identifiable
Problems: artifact, slight risk of fetal infection/injury, doubling or halving of the FHR, and
pick up of the MHR with fetal demise
1
,Other relative contraindications: syphilis, gonorrhea (not recommended but may be placed if
a clear benefit to a mother and fetus can be demonstrated by its use)
Describe external uterine monitoring - ANSWER The tocotransducer (TOCO) is a pressure
sensitive button-like device that detects changes in the abdominal contour when there is a
uterine contraction. The specific location is determined by abdominal palpation and is ide-
ally a smooth part of the uterus where no fetal small parts are felt. Usually this is the fundus
or whatever uterine contractions are most easily palpated
The TOCO can best provide: relative strength, approximate duration, and approximate fre-
quency of contractions but cannot determine actual intensity. PALPATION IS ESSENTIAL
Problems: include its inherent limitations, possibility of inverted contractions and issues with
obesity
Describe internal uterine monitoring - ANSWER IUPC allows for greater quantitative
measurement of uterine contraction frequency, duration, and intensity or peak intrauterine
pressure and resting tone
Three types: fluid-filled (other countries), transducer-tipped, and air-coupled or sensor-
tipped (what we used)
Measures: actual pressures in mmHg and most allow for amnioinfustion
Indications for use: Need for amnioinfusion, titration of oxytocin for induction or augmenta-
tion when external methods are not providing enough information, and lack of progress in
labor
Problems: user error, displacement, placental abruption/shearing, and a small risk of uterine
perforation
2
,What are the three types of IUPC monitors? - ANSWER Fluid-filled: also called the water
column method, was the 1st type of IUPC available and use dramatically decreased after in-
troduction of the transducer-tipped catheter. It works by transmitting the pressure gener-
ated by a contraction through a water column to a transducer located away from the source
of pressure, typically at the monitor site. This displaced fluid exerts pressure against a dia-
phragm in the transducer, generating changes in the electrical resistance of a series of wires.
These electrical changes are converted to measures of pressure.
Transducer-tipped: Introduced in the 1980s as an alternative to fluid-filled. The force exerted
by a uterine contraction is converted to an electrical signal that is transmitted through a wire
system to a fetal monitor where the uterine activity is displayed graphically on the fetal
monitor tracing
Sensor-tipped: Air-coupling technology, which is a newer method of IUPC monitoring, uses a
distally mounted flexible balloon in the uterus connected to an external reusable transducer
in the monitor cable. Similar to noninvasive blood pressure monitors, this catheter consists
of a membrane sensor at the tip of the catheter that communiated pressures through a mi-
crocolumn of air to a transducer located outside the body
What is the paper speed for EFM tracing? - ANSWER Changes in paper speed can sub-
stantially alter the appearance of the tracing. The commonly used paper in the US has mark-
ings on the vertical scale from 30-240 bpm with dividing lines at 10-bpm intervals. Should be
set to 3cm on the horizontal scale (slower than Europe)
What is artifact? - ANSWER Irregular variations or absence of the FHR on the fetal moni-
tor record resulting from mechanical limitations of the monitor, electrical interference, or
weak signal, appearing as gaps or dots. With FSE, artifact may appear in the form of irregular
lines with varying lengths.
FSE artifact vs arrhythmias: arrhythmias will be regular lines
What is half-counting in regards to the FHR? - ANSWER Most commonly seen when the
FHR is rapid, such as with fetal supraventricular tachycardia
3
, What is double-counting in regards to FHR? - ANSWER May occur during periods of brad-
ycardia
What are some troubleshooting interventions for fetal monitoring? - ANSWER Reposi-
tioning the US transducer, ensuring an adequate amount of coupling gel is used, and check-
ing for proper placement of FSE
Check maternal pulse, encourage maternal position changes, tighten belt as needed, check
connection to the power source as well as connections to the monitor, apply FSE if clinically
indicated
What are some patient education points for fetal monitoring? - ANSWER Education re-
garding available and recommended methods of fetal assessment should be customized for
each woman and is essential for women to make fully informed decisions about their health
care. Explain how equipment works. Use intermittent auscultation when able
What are some extrinsic influences on FHR patterns? - ANSWER Maternal influences
Uteroplacental perfusion
Umbilical circulation
Amniotic fluid characteristics
What are maternal influences on FHR patterns? - ANSWER Oxygenation status, hemoglo-
bin levels (ability to carry oxygen on each molecule), anything that affects uterine blood flow
(smokers, hypertension, hypotension), maternal cardiac output- will influence uterine blood
flow
What are uteroplacental circulation factors that influence FHR patterns? - ANSWER Uter-
ine blood flow is dependent on maternal BP. Factors affecting uterine blood flow include:
contractions, hypertonus, hypertension, hypotension, vasocontstriction.
Maternal blood enters the intervillous space in the placenta via spiral arteries... the ex-
change of gases and nutrients occur at the chorionic villi.
4
bination
In the US, the majority of women have EFM during some or all of their labors
Each modality has both pros and cons
Describe Doppler Ultrasound - ANSWER The doppler US transducer is used to assess FHR
characteristics and patterns. The transducer translates sound wave reflections into wave-
forms which are interpreted by a computer and then exported as an audible sound and a
waveform pattern.
Problems: FHR artifact, doubling, halving, and detection of maternal heart rate
Current ultrasound FHR signal processing uses autocorrelation techniques and interpretation
of EFM data is based on this assumption
Describe internal fetal electrode - ANSWER The FSE directly measures the FHR by meas-
uring R to R waves in successive QRS complexes. To place an FSE, adequate cervical dilation
(usually at least 2 cm) and ROM are needed.
Contraindications: placenta previa, hemophilia, maternal HIV, herpes infections, or when
presenting part is not identifiable
Problems: artifact, slight risk of fetal infection/injury, doubling or halving of the FHR, and
pick up of the MHR with fetal demise
1
,Other relative contraindications: syphilis, gonorrhea (not recommended but may be placed if
a clear benefit to a mother and fetus can be demonstrated by its use)
Describe external uterine monitoring - ANSWER The tocotransducer (TOCO) is a pressure
sensitive button-like device that detects changes in the abdominal contour when there is a
uterine contraction. The specific location is determined by abdominal palpation and is ide-
ally a smooth part of the uterus where no fetal small parts are felt. Usually this is the fundus
or whatever uterine contractions are most easily palpated
The TOCO can best provide: relative strength, approximate duration, and approximate fre-
quency of contractions but cannot determine actual intensity. PALPATION IS ESSENTIAL
Problems: include its inherent limitations, possibility of inverted contractions and issues with
obesity
Describe internal uterine monitoring - ANSWER IUPC allows for greater quantitative
measurement of uterine contraction frequency, duration, and intensity or peak intrauterine
pressure and resting tone
Three types: fluid-filled (other countries), transducer-tipped, and air-coupled or sensor-
tipped (what we used)
Measures: actual pressures in mmHg and most allow for amnioinfustion
Indications for use: Need for amnioinfusion, titration of oxytocin for induction or augmenta-
tion when external methods are not providing enough information, and lack of progress in
labor
Problems: user error, displacement, placental abruption/shearing, and a small risk of uterine
perforation
2
,What are the three types of IUPC monitors? - ANSWER Fluid-filled: also called the water
column method, was the 1st type of IUPC available and use dramatically decreased after in-
troduction of the transducer-tipped catheter. It works by transmitting the pressure gener-
ated by a contraction through a water column to a transducer located away from the source
of pressure, typically at the monitor site. This displaced fluid exerts pressure against a dia-
phragm in the transducer, generating changes in the electrical resistance of a series of wires.
These electrical changes are converted to measures of pressure.
Transducer-tipped: Introduced in the 1980s as an alternative to fluid-filled. The force exerted
by a uterine contraction is converted to an electrical signal that is transmitted through a wire
system to a fetal monitor where the uterine activity is displayed graphically on the fetal
monitor tracing
Sensor-tipped: Air-coupling technology, which is a newer method of IUPC monitoring, uses a
distally mounted flexible balloon in the uterus connected to an external reusable transducer
in the monitor cable. Similar to noninvasive blood pressure monitors, this catheter consists
of a membrane sensor at the tip of the catheter that communiated pressures through a mi-
crocolumn of air to a transducer located outside the body
What is the paper speed for EFM tracing? - ANSWER Changes in paper speed can sub-
stantially alter the appearance of the tracing. The commonly used paper in the US has mark-
ings on the vertical scale from 30-240 bpm with dividing lines at 10-bpm intervals. Should be
set to 3cm on the horizontal scale (slower than Europe)
What is artifact? - ANSWER Irregular variations or absence of the FHR on the fetal moni-
tor record resulting from mechanical limitations of the monitor, electrical interference, or
weak signal, appearing as gaps or dots. With FSE, artifact may appear in the form of irregular
lines with varying lengths.
FSE artifact vs arrhythmias: arrhythmias will be regular lines
What is half-counting in regards to the FHR? - ANSWER Most commonly seen when the
FHR is rapid, such as with fetal supraventricular tachycardia
3
, What is double-counting in regards to FHR? - ANSWER May occur during periods of brad-
ycardia
What are some troubleshooting interventions for fetal monitoring? - ANSWER Reposi-
tioning the US transducer, ensuring an adequate amount of coupling gel is used, and check-
ing for proper placement of FSE
Check maternal pulse, encourage maternal position changes, tighten belt as needed, check
connection to the power source as well as connections to the monitor, apply FSE if clinically
indicated
What are some patient education points for fetal monitoring? - ANSWER Education re-
garding available and recommended methods of fetal assessment should be customized for
each woman and is essential for women to make fully informed decisions about their health
care. Explain how equipment works. Use intermittent auscultation when able
What are some extrinsic influences on FHR patterns? - ANSWER Maternal influences
Uteroplacental perfusion
Umbilical circulation
Amniotic fluid characteristics
What are maternal influences on FHR patterns? - ANSWER Oxygenation status, hemoglo-
bin levels (ability to carry oxygen on each molecule), anything that affects uterine blood flow
(smokers, hypertension, hypotension), maternal cardiac output- will influence uterine blood
flow
What are uteroplacental circulation factors that influence FHR patterns? - ANSWER Uter-
ine blood flow is dependent on maternal BP. Factors affecting uterine blood flow include:
contractions, hypertonus, hypertension, hypotension, vasocontstriction.
Maternal blood enters the intervillous space in the placenta via spiral arteries... the ex-
change of gases and nutrients occur at the chorionic villi.
4
