Methods of Assessing Fetal Status

 Lecture Six: Methods of Assessing Fetal Status

NURS 2208

T. Dennis RNC, MSN

Objectives

• Discuss the use of ultrasound in pregnancy
• Discuss methods of antenatal fetal surveillance
• Identify antenatal surveillance indicators
• Compare NST, CST and BPP
• Contrast amniocentesis and CVS
• Discuss Leopold’s maneuver
• Compare various fetal heart rate patterns and interventions

Indications for Antenatal Surveillance (pg. 439)

• Decreased fetal movement
• Elevated maternal serum AFP
• Hemoglobinopathies
• Fetal heart rate arrythmias
• Infections
• Maternal disease
• PIH Pregnancy Induced Hypertension

Fetal Monitoring

Fetal oxygen supply must be maintained during labor to prevent fetal compromise and promote newborn health after birth.

• Reduction of blood flow through the maternal vessels.
• Reduction of the oxygen content in the maternal blood.
• Alteration in fetal circulation.
• Reduction in blood flow to the intervillous space in the placenta secondary to uterine hypertonus.

Monitoring Techniques

• Intermittent Auscultation
• Electronic Fetal Monitoring
• Fetal blood sampling
• FHR response to stimulation
• Fetal oxygen saturation monitoring
• Cord blood sampling

Determination of Fetal position and Presentation (pg. 515)

• Inspection
• Palpation: Leopold’s Maneuvers: 1) Find the head/buttocks, 2) Find the back, 3) Determine presenting part, 4) Determine brow
• Vaginal examination
• Ultrasound

Intermittent Auscultation

• Listening to fetal heart sounds at periodic intervals to assess the FHR.
• Fetoscope or doppler
• Perform Leopold’s to determine fetal back
• Palpate maternal pulse
• Count between contractions for baseline and 30 seconds after the contraction
• 1 hr, 30 minutes, 15 minutes or 30 minutes, 15 minutes and 5 minutes.

Electronic Fetal Monitoring

• External method involves the use of external transducers placed on the maternal abdomen to assess uterine contractions and the FHR.
• Internal method uses spiral electrode and intrauterine pressure catheter to monitor and record FHR, uterine activity and intrauterine pressure.

External Fetal Monitoring

• FHR: Ultrasound transducer
• High frequency sound waves
• used antepartally and intrapartally
• noninvasive
• Does not require RBOW or dilatation
• Uterine activity: Tocotransducer
• Monitors frequency and duration of contractions by use of a pressure sensing device on abdomen
• Antepartally and intrapartally
• Noninvasive

External Fetal Monitoring

 

Internal Fetal Monitoring

• FHR: Spiral electrode
• converts fetal ECG to via cardiotachometer
• Used when RBOW
• Cervix dilated
• Penetrates presenting part
• Must be securely attached
• Contractions: IUPC
• measures frequency, duration and intensity of contractions
• two types
• measure intrauterine pressure at catheter tip
• Used with RBOW and dilatation

Internal Fetal Monitoring

Baseline Fetal Heart Rate

• Baseline fetal heart rate
• Tachycardia
• Bradycardia
• Variability

Baseline Fetal Heart Rate

• The average rate during a ten minute segment that excludes periodic and non-periodic (episodic) changes, periods of marked variability, and segments that vary by more than 25 BPM.
• Normal range is 110-160.

Tachycardia

• A baseline FHR above 160 BPM for a ten minute period or greater.
• Can be considered an early sign of fetal hypoxia.
• Can result from maternal or fetal infection, maternal hyperthyroidism, or fetal anemia.
• May occur in response to drugs such as terbutaline, atropine, cocaine.

Bradycardia

• A baseline FHR below 110 BPM for a period greater than 10 minutes.
• Considered a later sign of fetal hypoxia.
• Known to occur before fetal demise.
• Can occur from drugs (anesthetics, prolonged compression of the umbilical cord, maternal hypotension or hypothermia.

Variability

• Described as irregular fluctuations in the baseline FHR of 2 cycles per minute or greater.
• Described as short term or long term.
• Absent or undetected variability
• Minimal variability ( < 5 BPM)
• Moderate variability (6 to 25 BPM)
• Marked variability (> 25 BPM)

Variability

• In clinical practice used to describe fluctuations in the FHR.
• Absence of variability is considered non-reassuring.
• May result from fetal hypoxemia and acidosis (may be related to drugs).
• A temporary decrease can occur with fetal sleep.

Periodic and Non-periodic FHR Changes

Accelerations

• A visually apparent abrupt increase in FHR above the baseline rate.
• Increase is 15 BPM or greater that lasts 15 seconds or more with return to baseline in less than 2 minutes.
• Can be periodic or non-periodic (episodic).
• Indications of fetal well being.

Decelerations

• May be benign or non-reassuring.
• Described by their relation to the onset and end of the contraction and shape.
• Three types:
• Early decelerations
• Late decelerations
• Variable decelerations
• Prolonged Decelerations

Early Decelerations

• Gradual decrease in and return to FHR baseline.
• In response to head compression.
• Uniform in shape.
• Seen with pushing.
• No intervention required.

Late Decelerations  

• Begins after beginning of ctx and ends after end of the contraction.
• May be correctable or ominous
• Caused by uteroplacental insufficiency

Variable Decelerations

• Caused by umbilical cord compression
• Abrupt in descent and return to baseline
• May occur early or late in labor
• May be repetative
 

Prolonged Decelerations

• May be caused by vaginal exam, spiral electrode application, etc.
• Usually isolated events
• May occur just before fetal death.

Fetal Well-being

• Can be measured by response of the FHR to uterine contractions.
• FHR patterns can be described as reassuring or non-reassuring.

Reassuring FHR patterns

• Baseline FHR in the normal range of 110 to 160 BPM with no periodic changes and a moderate baseline variability.
• Accelerations with fetal movement.

Non-reassuring Patterns

• Progressive increase or decrease in the fetal baseline
• Tachycardia of 160 BPM or more
• Progressive decrease in baseline variability
• Severe variable decelerations
• Late decelerations of any magnitude
• Absence of FHR variability
• Prolonged deceleration
• Severe bradycardia

Normal Uterine Activity

• Occurring every 2 - 5 minutes
• Lasting less than 90 seconds
• Moderate to strong in intensity (by palpation or 100mm Hg by IUPC)
• 30 second lapse period between contractions
• Uterine relaxation between ctx by palpation or 15 mm Hg by IUPC

Fetal Compromise

• The goals of intrapartum FHR monitoring are to identify and differentiate the rassuring from the nonreassuring , which can be indicative of fetal compromise.
• Nonreassuring FHR patterns are those associated with fetal hypoxia (a deficiency in oxygen in the arterial blood) and if uncorrected hypoxia (at the cellular level).

Nonstress Test NST
(pg. 452-454)

• A reactive NST shows two or more accelerations of 15 bpm or more within 20 minutes of beginning the test.
• A nonreactive NST contains a tracing that does not meet the above criteria. Accelerations are < two in number or < 15 bpm or no accelerations are present.

Contraction Stress Test CST
(pg. 455)

• Contractions occurring spontaneously
• Nipple stimulation
• Necessary component is the presence of three uterine contractions of at least 40 sec duration in 10 minute span
• Not done prior to prior to 28 wks gestation
• NEGATIVE, POSITIVE & EQUIVOCAL

Biophysical Profile (BPP)

• Assessment of 5 variables in the fetus that help to evaluate fetal risk: breathing movement, body movement, tone amniotic fluid volume, and fetal heart rate activity.
• A score of 8 to 10 is normal.
• A score of 6 or below indicates fetal compromise

Fetal Acoustic Stimulation Test

Let’s “buzz” the baby!!!!!

Ultrasound

• Most common diagnostic procedure
• 70% of pregnant women have at least one
• Abdominal, vaginal, or labial
• May be basic or limited
• Can evaluate both structural and functional characteristics
• BP diameter, head circumference, femur length, abdominal measurements
• Fetal growth, congenital anomalies, placental growth and location, cervical length

  

Amniocentesis (pg. 457-459)

• A simple procedure: needle is inserted through the maternal abdomen into the uterine cavity to withdraw a sample of amniotic fluid.
• Early pregnancy: DNA studies
• Late Pregnancy: Lung maturity
• Complications: Preterm labor, fetal scratches, maternal hemorrhage, infection, Rh sensitization (RhoGam may be indicated)

Tocolytic Therapy

• Tocolysis can be achieved by administering drugs that inhibit uterine contractions.
• May be used during management of fetal compromise.
• Magnesium sulfate, terbutaline, nifedipine may be used.

Maternal Positioning

• Maternal supine hypotensive syndrome is caused by the weight and pressure of the gravid uterus on the ascending vena cava when the woman is in a supine position.
• A side-lying position or semi-fowlers position with a lateral tilt to the uterus is recommended.

Other Available Tests
(pg. 459-467)

• AFP (Amniotic Fluid)
• Rh sensitized pregnancies
• Fetal Maturity
• L/S ratio and PG
• CVS
• Fetoscopy
• Percutaneous Umbilical Blood Sampling
• MRI

EFM: Nursing Diagnosis

• Maternal anxiety related to lack of knowledge about use of electronic fetal monitor.
• Risk for fetal injury related to inaccurate placement of transducers/electrodes, misinterpretation of results or failure to use other assessment techniques to monitor fetal well-being.

Nursing Assessment & Diagnosis

• Knowledge Deficit related to insufficient information about the fetal assessment test and its purpose, benefits, risks, and alternatives
• Fear related to the specific test or possible unfavorable results
• Disruption in bonding due to high risk label

Questions?

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Source : Abraham Baldwin Agricultural College

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