Intrapartum Fetal Surveillance

Electronic Fetal Monitoring (EFM)• Ultrasound (US)• Tocotransducer

(TOCO)• Internal Fetal Scalp

Electrode (IFSE)• Intrauterine

Pressure Catheter (IUPC)• Doppler US

EFM

• The primary objective of EFM is to provide information about fetal oxygenation and prevent fetal injury that could result from impaired fetal oxygenation during labor.

• This is achieved by detecting fetal heart rate changes early before they are prolonged and profound.

Fetal Oxygenation

• Adequate fetal oxygenation requires five related factors:

• Adequate maternal blood flow and volume to the placenta.

• Adequate oxygen saturation in maternal blood.

• Adequate exchange of oxygen and carbon dioxide in the placenta.

• An open circulatory path between the placenta and the fetus through vessels in the umbilical cord.

• Adequate fetal circulatory and oxygen-carrying functions.

Uteroplacental Exchange

• Review: Oxygen rich and nutrient rich blood from the mother enters the intervillous spaces of the placenta through the spiral arteries.

• Oxygen and nutrients in the maternal blood pass into the fetal blood that circulates in capillaries in the intervillous spaces.

• CO2 and other waste products pass from the fetal blood into the maternal blood at the same time.

• Maternal blood carrying fetal waste products drains from the intervillous spaces through endometrial veins and returns to the mother’s circulation for elimination.

Exchange continued:

• Substances pass back and forth between mother and fetus without mixing of maternal and fetal blood if fetal capillaries remain intact.

• During labor contractions gradually compress the spiral arteries, temporarily stopping maternal blood flow into the intervillous spaces.

• Thus during contractions the fetus depends on the oxygen supply already present in body cells, along with intervillous spaces. Oxygen supply in these areas is enough for about 1 to2 minutes.

Baseline FHR

• The average heart rate measured over a 2 minute period within a 10 minute window

• Normal=110-160

• Brady=<110 for 10 minutes

• Tachy=>160 for 10 minutes

• Pre-term may have >160 due to immature parasympathetic NS

Variability

• Most important component of the FHR• Irregular fluctuations in the baseline fetal heart rate.• Measured as the amplitude of the peak to trough in bpm• Evaluates fetal autonomic nervous system, adequate 02

status promotes normal FX• Long-term variability(LTV) broader fluctuations of the

FHR• Short-term variability(STV) beat-to-beat variability, only

with IFSE• No variability=fetal compromise

Reassuring pattern

Accelerations 15 bpm X 15 sec

Moderate variability = 6=25 bpm variation

Minimal variability = <5 bpm variation

Periodic changes

• Accelerations (accels) – transitory abrupt increases in the FHR above the baseline,15 bpm above baseline FHR greater than 15 sec less than 2 minutes. Reassuring; thus denoting fetal movement and fetal well-being and are the basis for nonstress testing.

• Decelerations- transient fall in FHR caused by stimulation of the parasympathetic NS.• Early=head compression

• Late=utero-placental insufficiency

• Variable=cord compression

Early decelerations = head compression

Head compression

• Deceleration with each contraction

• Mirror image when contraction beginsthe heart rate begins to drop

• Action – prepare for birth

Late decelerations = uteroplacental insufficiency

Late decelerations

• Deceleration with each contraction

• Late onset, usually see a decrease in variability

• Action=intra-uterine resuscitation• If on Pitocin – turn it OFF

• Increase mainline fluid volume, bolus with LR

• O2 via face mask at 8-10 L

• Turn to left side, or whatever position best for blood flow

• Scalp stimulation?

Variable decelerations = cord compression

Variable deceleration

• Occurs randomly

• Not a problem if occasional and returns to baseline

• If frequent, long return, < variability=intrauterine resuscitation.• Turn to left side

• Pitocin off and increase fluids

• O2 via face mask at 8- 10 L

• Amnioinfusion – warm NS

Prolapsed cord

• Do not remove fingers after exam

• Relieve pressure from presenting part

• Call for help, prepare for emergency C/S

• Remain calm

EFMLimitations

• Reduced mobility

• May require frequent adjustment of equipment to obtain continuous tracing

• Best identifies the well oxygenated fetus…does not reliably identify the compromised fetus

• Increased operative intervention

Interventions

• Intra-uterine resuscitation

• Measures create anxiety, fear, and loss of control

• Remain calm, educate patient and family, and choose words wisely

• Report all interventions to MD

EFM Advantages

• Supplies more data, becomes part of the permanent record

• Shows FHR in relation to stimuli

• Provides a feeling of safety for the parent

• Allows nurse/patient ratio to be 1:2 with central monitoring

Fetal Scalp Electrode (FSE)

Intrauterine Pressure Catheter (IUPC)

Amnioinfusion

• Indications: persistent, deep variable decelerations, meconium stained amniotic fluid.

• Requires IUPC

• Warm NS fluid of choice

• Infusion pump

• Weigh all chux and record output