CEFM Study Guide Flashcards
Describe Fetal Heart Rate Monitoring *** EFM may be external, internal or a combination
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 *** The doppler US transducer is used to assess FHR characteristics and
patterns. The transducer translates sound wave reflections into waveforms 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 *** The FSE directly measures the FHR by measuring 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
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 *** 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 ideally 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 frequency 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 *** 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 augmentation 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
What are the three types of IUPC monitors? *** Fluid-filled: also called the water column method, was
the 1st type of IUPC available and use dramatically decreased after introduction of the transducer-
tipped catheter. It works by transmitting the pressure generated 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 diaphragm 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 microcolumn of air to a transducer
located outside the body
What is the paper speed for EFM tracing? *** Changes in paper speed can substantially alter the
appearance of the tracing. The commonly used paper in the US has markings 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? *** Irregular variations or absence of the FHR on the fetal monitor 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? *** Most commonly seen when the FHR is rapid, such as
with fetal supraventricular tachycardia
What is double-counting in regards to FHR? *** May occur during periods of bradycardia
What are some troubleshooting interventions for fetal monitoring? *** Repositioning the US
transducer, ensuring an adequate amount of coupling gel is used, and checking 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? *** Education regarding 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? *** Maternal influences
Uteroplacental perfusion
Umbilical circulation
Amniotic fluid characteristics
What are maternal influences on FHR patterns? *** Oxygenation status, hemoglobin 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? *** Uterine 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 exchange of gases
and nutrients occur at the chorionic villi.
Placental transfer can be affected by: Placental area (IUGR, abruption), concentration gradients,
diffusing distance, uterine blood flow, umbilical blood flow
What are the mechanisms of exchange between fetal and maternal blood in the placenta? *** Simple
diffusion: oxygen, carbon dioxide, many drugs
Facilitated diffusion: glucose, carbs
Describe Fetal Heart Rate Monitoring *** EFM may be external, internal or a combination
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 *** The doppler US transducer is used to assess FHR characteristics and
patterns. The transducer translates sound wave reflections into waveforms 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 *** The FSE directly measures the FHR by measuring 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
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 *** 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 ideally 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 frequency 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 *** 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 augmentation 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
What are the three types of IUPC monitors? *** Fluid-filled: also called the water column method, was
the 1st type of IUPC available and use dramatically decreased after introduction of the transducer-
tipped catheter. It works by transmitting the pressure generated 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 diaphragm 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 microcolumn of air to a transducer
located outside the body
What is the paper speed for EFM tracing? *** Changes in paper speed can substantially alter the
appearance of the tracing. The commonly used paper in the US has markings 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? *** Irregular variations or absence of the FHR on the fetal monitor 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? *** Most commonly seen when the FHR is rapid, such as
with fetal supraventricular tachycardia
What is double-counting in regards to FHR? *** May occur during periods of bradycardia
What are some troubleshooting interventions for fetal monitoring? *** Repositioning the US
transducer, ensuring an adequate amount of coupling gel is used, and checking 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? *** Education regarding 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? *** Maternal influences
Uteroplacental perfusion
Umbilical circulation
Amniotic fluid characteristics
What are maternal influences on FHR patterns? *** Oxygenation status, hemoglobin 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? *** Uterine 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 exchange of gases
and nutrients occur at the chorionic villi.
Placental transfer can be affected by: Placental area (IUGR, abruption), concentration gradients,
diffusing distance, uterine blood flow, umbilical blood flow
What are the mechanisms of exchange between fetal and maternal blood in the placenta? *** Simple
diffusion: oxygen, carbon dioxide, many drugs
Facilitated diffusion: glucose, carbs
