Ultrasound
Ultrasound
• Definition -- an instrument which uses
reflective sound waves as they travel in
tissue to visualize structures in the body
Purposes of Performing
an Ultrasound
•
•
•
•
•
Validate the pregnancy
Determine how advanced the pregnancy is
Detect congenital anomalies and problems
Localize the placenta
Assess fetal viability – heartbeat, breathing
movements
• Diagnose cardiac problems
• Detect fetal presentation, number of fetus
Ultrasound
• It is a non-invasive and painless procedure
• Results are immediate
• Allows the mother and family to “see” the
baby
Ultrasound Nursing Care
• Make sure that the patient has a full bladder
• Place patient on back with a towel roll under
one hip -- allowing better perfusion of the
placenta
• The test requires about 20 - 30 minutes
Alpha - Fetoprotein AFP
• Measurement of a protein produced by the
yolk sac and fetal liver. Main protein in fetal
plasma. Diffuses from fetal plasma to fetal
urine, excreted in amniotic fluid.
• Measured via maternal serum or
amniocentesis
• Elevated levels of AFP may be indicative of
open neural tube defects because the AFP
leaks out of the fetal circulation into the
amniotic fluid and chromosome
abnormalities.
Chorionic Villi Sampling
• Removal of small
tissue specimen
from the fetal
portion of the
placenta
• Tissue obtained
about 10-12 weeks
gestation
• Chromosomal
studies performed
Chorionic Villus Sampling
• Advantage – can be done earlier than
an amniocentesis to detect problems.
• Disadvantage – spontaneous abortion
AMNIOCENTESIS
Collection of Amniotic Fluid for Testing
Amniocentesis
•
•
•
•
An invasive procedure
Requires a consent form to be signed
Performed about 14 - 16 weeks gestation
Patient must be informed of possible
complications
– Trauma
– Infection
– Hemorrhage
Amniocentesis
• Preparation
– Permits signed
– Vital Signs and FHT’s
– Abdominal prep and scrub
• Procedure
– Area of insertion is anesthesized and a needle inserted into
the amniotic cavity and 5 - 30 ml of fluid withdrawn for
analysis
• Post care / Discharge Teaching
– Vital signs and FHT’s normal
– No leakage of fluid from site
– Teach patient to report -- lack of fetal movement, discharge
or bleeding, abdominal pain, or fever
Amniocentesis
• Why is an Ultrasound performed as part of the
procedure?
• To detect placement of the placenta
Amniocentesis
Tests Performed
• Triple Test
– AFP
– hCG
– Unconjugated estriol
• Genetic studies
– Most commonly used to diagnose Downs
• Fetal Lung Maturity
– L/S ratio – lecithin-sphingomyelin ratio
L/S Ratio
Lecithin / Sphingomyelin Ratio
• Lecithin is a major constituent of surfactant.
As surfactant increases in the lungs, the levels
of lecithin should also increase.
• Lecithin should become 2 - 3 times greater
than sphingomyelin by about 35 weeks
• Fetal maturity is attained when the L/S ratio is
2:1
Assesses Fetal Lung Maturity
Karotyping and
Cell Enzyme Studies
Determine
sex of the
fetus
Normalcy
of
Chromosomes
Non-Stress Test
Evaluation of Fetal Status
• Observation of fetal heart rate associated with
fetal movement.
• With movement of the fetus, the FHR should
increase, or accelerate
• This test is based on the knowledge that when
the fetus has adequate oxygenation and an intact
CNS, there are accelerations of FHR with
movement.
Procedure for the NST
• Electronic fetal monitor is applied
• As the NST is done, fetal movements are
documented
• Compare the FHR with the fetal movements
• Results:
– Reactive -- two accelerations of 15 BPM lasting 15
seconds, associated with fetal movement. This is an
indication of fetal well-being
– Nonreactive -- no accelerations of FHR. Indication of
need for further assessment
Non-Stress Test
Example of a reactive non-stress test (NST). Accelerations of
15 beats per minute lasting 15 seconds with each fetal
movement (FM). Top of strip shows FHR; bottom of strip shows
uterine activity tracing. Note that FHR increases (above the
baseline) at least 15 beats and remains at that rate for at least
15 seconds before returning to the former baseline.
Non-Stress Test
Example of a nonreactive NST. There are no
accelerations of FHR with FM. Baseline FHR is 130
beats per minute. The tracing of uterine activity is on
the bottom of the strip.
NST Management Scheme
***If test is non-reactive, woman is re-tested. If continues to
remain non-reactive, will schedule an OCT.
Contraction Stress Test
Oxytocin Challenge Test
CST
OCT
• A means of identifying the fetus that is at
risk for intrauterine asphyxia.
• Usually shows if there is placental
insufficiency.
Procedure for an OCT
•
•
•
•
Oxytocin (Pitocin) stimulation started IV
Electronic fetal monitor attached
Goal -- have 3 contractions in 10 minutes
Results:
– Negative -- 3 contractions in 10 minutes
with NO signs of late decelerations
– Positive -- repetitive persistent late
decelerations occurring with more than half
the contractions
Oxytocin Challenge Test
Example of a positive contraction stress test (CST). Repetitive
late decelerations occur with each contraction. Note that there
are no accelerations of FHR with three fetal movements (FM).
The baseline FHR is 120 beats per minute. Uterine contractions
(bottom half of the strip) occurred four times in 12 minutes.
Biophysical Profile
Comprehensive assessment of five
Biophysical variables:
1. Fetal breathing movement
2. Fetal movements of body or limbs
3. Fetal tone (extension and flexion of
extremities)
4. Amniotic fluid volume – visualized as
pockets around the fetus
5. Reactive FHR with activitity (reactive NST)
Biophysical Profile
By combining these five assessments, the BPP helps to
identify the compromised fetus and to confirm the healthy
fetus
Since it combines several assessments, it is a better
indicator of fetal well-being
Biophysical Profile
• A score of 2 is assigned to each normal finding
for a maximum score of 10.
• Scores of 8-10 are considered normal
• Lower scores are associated with a
compromised fetus and warrant further
assessment and possible delivery of the baby.
Kick Counts
• The mother should assess fetal movements
called “kick counts” each day.
• Fetal movement is associated with the
condition of the fetus.
The End