Monday 9 July 2012

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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SourceAbraham Baldwin Agricultural College
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