Fetal Assessment
At what gestational age can a non-stress test be performed?
After 28 weeks *the results expected are different after 32 weeks
When may the fetal movements decrease?
Close to term
What does a non-stress test measure?
-adequate oxygenation -healthy neural pathway from the fetal CNS to the heart -ability of fetal heart to respond to stimuli
When is a woman advised to start counting fetal movements?
-If high risk pregnancy: start at 28-30 weeks -If low risk: start at 34-36 weeks
When is CVS performed?
10-13 weeks gestation
When is the quad screen performed?
16-18 weeks gestational age
Around how many weeks can a mother perceive fetal movement?
20 weeks if normal BMI (may be later for those with higher BMI)
What does the quad screen detect?
4 things: Alpha fetoprotein (AFP) Unconjugated estriol hCG Inhibin A
When can fetal movement be seen on an ultrasound?
7 weeks gestational age
What is normal for fetal movement in a close to term baby?
90% of the time in quiet alert or active sleep state (but FM still occurs) May be inactive for 40 minute increments
What is the predictive value of the biophysical profile?
99.9% So if score comes back low, be concerned.
When can a woman expect increased fetal movements?
9PM - 1 AM For a shift worker: 9AM-1PM Reason: Mother's movement lulls the fetus to sleep, so the fetus will often be more active when mom is resting
How is CVS performed?
An invasive procedure that obtains fetal cells. A tiny tissue sample is taken from the villi of the chorion, which forms the fetal part of the placenta.
What are good/expected fetal heart rate accelerations during a non-stress test?
At 28 weeks gestational age, looking for 10 beats above baseline for 10 seconds. For 32 weeks gestational age, looking for 15 beats above baseline for 15 seconds.
When is the Multiple Marker Screen performed?
Between weeks 11-14 (first trimester)
When is the anatomy scan performed?
Between weeks 17-21
What are some diagnostic tests in pregnancy?
Chorionic Villus Sampling (CVS) Amniocentesis
Benefits of amniocentesis
Detection of genetically linked conditions Possible relief of anxiety May help with decision-making
Goals of fetal assessment in 3rd trimester
Determine presence of fetal well-being Prevent fetal compromise and/or demise
When is ultrasound done in pregnancy?
Early on to confirm pregnancy Anatomy scan As an adjunct to other procedures, like amnio and CVS
If patient receives a 4 on the biophysical profile, what is likely to happen?
Emergency c-section
What is a non-stress test (NST)?
Evaluates uteroplacental sufficiency by noting fetal heart rate accelerations in association with fetal movement
Influencing variables to fetal movement
Fetal resting state, maternal glucose load, medications, exercise -For example, if mom takes a medication that causes sleepiness, this will affect baby -If mom eats some sugar or has a good workout, this may make the baby energized
What does the Multiple Marker Screen test?
From maternal blood: Human chorionic gonadotropin (hCG) and PAPP-A On ultrasound: nuchal translucency (NT)
Screening Values for open neural defects
High AFP
What results from the Multiple Marker Screen test would indicate an increased risk for Down Syndrome?
High hCG Low PAPP-A NT > 3mm
What variables impact the accuracy of the quad screen?
Incorrect calculation of: gestational age maternal weight race presence of diabetes
How is amniocentesis performed?
Invasive procedure Removal of amniotic fluid with a needle
What does a screening test identify?
It identifies risk factors. Does not give definitive results! Examines results from a maternal blood draw. Estimates likelihood of abnormality (ex. 1/8 or 1/800)
What does a significant decrease in fetal movement indicate?
It is a red flag and requires further testing to check fetal well-being
Non-Invasive Prenatal Testing (NIPT)
Karyotypes a small amount of fetal DNA extracted from maternal blood. Tests for: Chromosomal abnormalities (Down Syndrome, Trisomy 18, Trisomy 13) Sex Chromosome abnormalities (Turner Syndrome, Klinefelter, Triple X and 47, XYY syndrome) More accurate than quad screen!
What is important patient teaching for screening tests?
Patients should be taught and counseled before ANY screening test. Take into consideration cultural and religious factors. Let them know a screening test is NOT diagnostic and can lead to false positives, which may lead to anxiety and further invasive testing that may end up not being necessary.
When is the Alpha Fetoprotein Screening done?
Performed between 15-20 weeks (timing is critical)
Nurse implications for CVS and amniocentesis
Review procedure and risks: Vaginal bleeding, cramping, SAB, limb abnormalities (CVS), PPROM, infection, chorioamnionitis, fetal maternal hemorrhage Post procedure: Report fever, leakage of fluid, vaginal bleeding, abdominal pain
What do low levels of AFP mean?
Risk for chromosomal abnormalities
What do elevated levels of AFP mean?
Risk for neural tube defects
What procedures could give a false positive for the Quad Screen?
Screening after any invasive procedure elevates the chance of a false positive result (ex. Amniocentesis and CVS)
What is the purpose of the Quad Screen?
Screening for Down Syndrome and/or Open Spinal Bifida (OSB)
Important Patient Education for invasive procedures
Signs and symptoms of miscarriage
Risks for CVS procedure
Spotting/bleeding, infection, SAB (higher risk than amniocentesis)
What are the risks of amniocentesis?
The risks are less than 1% for all pregnancies: Vaginal bleeding infection miscarriage amniotic fluid leakage
Who should be tested?
Those with genetic Risk Factors: family history ethnic groups with high risk X-linked conditions Advanced Maternal Age (Will be 35 years or older at DELIVERY)
What is nuchal translucency?
Ultrasound measures the thickness of the fluid buildup at the back of the developing baby's neck. If this area is thicker than normal, it can be an early sign of Down syndrome, trisomy 18, or heart problems.
What happens if the fetus is non-reactive after 20 minutes?
Wait another 40 minutes to allow for sleep-cycle. If still non-reactive, will be referred for biophysical profile
Patient Education-- Rhogam
With all invasive procedures, must take into account the maternal blood type. If you have Rh- mom and Rh+ dad, the baby may be Rh+ and antigens could enter mother's blood during delivery. In response to fetal Rh antigens, the mother will produce anti-Rh antibodies If mom becomes pregnant with another Rh+ fetus, her anti-Rh antibodies will cross the placenta and damage fetal RBCs Rhogam is the solution: Given IM at 28 weeks gestation to Rh- moms If at birth the baby is indeed Rh+, mom receives another Rhogam injection within 72 hours of the birth (if baby is Rh-, can hold the second dose)
When is amniocentesis performed?
between 16-18 weeks of gestation an early amniocentesis can be performed between 11-14 weeks, but there is an increased risk for SAB
What is an anatomy scan screening?
congenital anomalies head-to-toe gender amniotic fluid placenta
What should a woman do if decreased fetal movement persists?
go to hospital for a non-stress test
From the quad screen, what results would indicate risk for Down Syndrome?
low estriol and low AFP high inhibin A, high hCG
What are two tests that are often used to measure fetal well being in the third trimester?
non-stress test (NST) biophysical profile
What should a woman do first if she feels no or little fetal movements?
rest, food, fluids
What is a biophysical profile?
scoring system to evaluate fetal well being (high risk pregnancies, or when there is maternal/physician concern like decreased fetal movements or non-reactive NST) Five parameters: 1) NST 2) Fetal tone (bending of knees, elbows?) 3) Fetal movement 4) Fetal breathing 5) amniotic fluid index Can receive either a 0 or a 2 for each category. 8-10 is considered normal. 8 is given more frequently than 10 due to the patients often being referred after receiving a 0 on the NST.
Amniocentesis & CVS Indications
• Advanced maternal age (AMA) • Previous child with chromosomal abnormalities • Family history • Ultrasound diagnosis of fetal anomalies • Abnormal screening test • To diagnose fetal infection or hematologic disorder
Fetal Movement Counting
• Non-invasive and low tech • Mother can do herself when taught by a nurse • Increases awareness of fetal well-being; highly-accurate
Interpretation of values for biophysical profile
• Normal = 8 • Equivocal = 6 • Abnormal = 4
Important patient education for ultrasound/sonogram?
•Assure that patient understands reason for the sonogram •Describe preparation •Assure that patient understands results or if further testing/evaluation is needed
What is the procedure for the non-stress test?
•Best if the patient is not fasting and has not smoked recently •External monitoring Tocodynamometer over the fundus Transducer over the fetal heart •Reactive NST after a 20 minute period of observation
What is an ultrasound?
•High frequency sound waves create an image •Waves interface with solid structures •Energy is reflected to the transducer --> creates electrical voltage--> The voltage creates an image on the screen •2D or 3D of 4D (higher the level, higher the detail. Typically 2D is done.)
Third Trimester fetal assessment
•Issues of intrauterine environment •Maternal factors that affect growth & development of the fetus: Is the fetus better off inside or out?
Screening Values for Down Syndrome
Low AFP, estriol and PAPP-A High hCG and inhibin A
Summary of the gestational age for various screening/diagnostic procedures.
Multiple Marker Screen: 11-14 weeks Quad Screen: 16-18 weeks Alpha Fetoprotein (AFP): 15-20 weeks (timing critical for accuracy!) Amnio: 16-18 weeks (can be done at 11-14 weeks, but with increased risk for complications, specifically miscarriage) CVS: 10-13 weeks Non-stress test: After 28 weeks/32 weeks (different results expected for different gestational ages) Biophysical Profile: often done after a concerning NST, but may be performed weekly in a high risk pregnancy