Chapter 10: Antepartum Fetal Assessment Flashcards
What factors increase the risk for the fetus during pregnancy (indicates a need for fetal diagnostic testing)?
- Medical Conditions: diabetes, HTN, seizure disorders, autoimmune diseases
- Demographic Factors: age (<16 or >35) and poverty
- Obstetric Factors: previous pre-term labor, stillborn or infant that has had congenital anomalies
- Pre-existing maternal factors: prepregnancy BMI that is over or underweight, use of drugs, etc.
What are indications for antepartum fetal diagnostic testing?
- To detect congenital anomalies
2. To evaluate the condition of the fetus
Ultrasounds in pregnancy can be used to
- Confirm pregnancy
- Verify location of pregnancy
- Identify multifetal gestations
- Determine gestational age
- Confirm viability of fetuses
- Evaluate fetal anatomy
- Assess fetal growth
- Identify the amount of fluid
- Identifying fetal anomalies
Abdominal Ultrasound
Most often used during the second and third trimesters, allowing clear views of the fetus and placenta.
Transvaginal Ultrasound
Allows clear visualization of the uterus, gestational sac, embryo and pelvic structures such as the ovaries and Fallopian tubes during the first trimester.
Ultrasound Risks
Thought to be very safe
Amniotic Fluid Index
An ultrasound examination in which the vertical depth of the largest fluid pocket in each of the four quadrants of the uterus is measured and totaled.
Normal AFI at 20 weeks
700-1000 mL
What AFI indicates (Poly)Hydramnios?
AFI higher than 18-20 cm
What AFI indicates Oligohydramnios?
AFI <5 cm
What are associated complications of (poly)hydramnios?
- Diabetes (fetal polyuria)
- CNS anomalies (irritates the CNS -> increase in fetal urination)
- GI anomalies
- Premature rupture
- Overdue pregnancy
What are associated complications of oligohydramnios?
- Poor placental blood flow
- Preterm membrane rupture
- Failure of the fetal kidney development
- Blocked urinary excretion
Alpha-fetoprotein Testing
- Tests the level of maternal serum alpha-fetoprotein (plasma protein produced by the fetus) because the level of alpha-fetoprotein is altered by fetal age and number of fetuses.
- Accurate gestational age is needed when testing.
When should alpha-fetoprotein testing be done?
Time sensitive -> must be done between 15-20 weeks
What is the purpose of alpha-fetoprotein testing?
Screens for anomalies such as trisomy 21, 18, 13 and NTD
What are the risks for alpha-fetoprotein testing?
- 1 in 20 are false positive
- Can be costly
- Small risk of miscarriage and premature rupture
Amniocentesis
- Transabdominal puncture of the amniotic sac to obtain a sample of amniotic fluid that contains fetal cells and biochemical substances for laboratory examination.
- Much more accurate measure for advanced maternal age moms.
When should amniocentesis be performed?
Best performed at 15-20 weeks of gestation because adequate fluid volume and the quantity of viable fetal cells provide the best sample for evaluation.
What is amniocentesis used for?
- The most common, to identify chromosomal abnormalities.
- Advance maternal age
- Gender determination
- Pregnancy after 3 or more spontaneous abortions
- Elevated levels of maternal serum alpha-fetoprotein or multiple-marker screen that remain unexplained
- Maternal Rh sensitization of maternal Rh-negative blood to fetal Rh-positive blood
What are the risks when undergoing amniocentesis?
-Pregnancy loss rate of less than 1%. (Loss rate of 2%-5% noted after early amniocentesis)
Non-stress Test
A method for evaluating fetal status during the antepartum period by observing the response of the fetal heart rate to fetal movement.
What is the purpose of the nonstress test?
- Identifies whether an increase in the FHR occurs when the fetus moves.
- This indicates adequate oxygenation, a healthy neural pathway from the fetal CNS to the fetal heart and the ability of the fetal heart to respond to stimuli.
When should a nonstress test be performed?
Can start at 28 weeks because the CNS is considered mature at this time.
Usually done between 30-32 weeks.
How is a nonstress test evaluated?
- External electronic monitoring equipment is attached to the woman’s abdomen to detect fetal heart rate and any contractions.
- An ultrasound transducer to record fetal heart activity is secured on the woman’s abdomen where the fetal heart is heard most clearly.
- Next, a tocotransducer, which detects uterine activity and fetal movement is secured to the abdomen.
- Fetal reactivity is categorized as reactive (reassuring) and non reactive (nonreassuring)
What are the risk factors of the nonstress test?
-false-positive test results can occur
-
What are nursing interventions from findings of the nonstress test?
Used to stimulate the fetus to elicit accelerations in the FHR through:
- Vibroacoustic stimulation
- Manipulation of the woman’s abdomen
- Having the mother drink orange juice to raise her glucose level
What is a biophysical profile (BPP)?
Methods for evaluating fetal status during antepartum period based on five variables originating with the fetus.
What are risk factors of a biophysical profile?
-
What is a fetal movement assessment?
Assessment of movements by the fetus, “kick counts”.
Fetal movement is associated with fetal condition and daily evaluation of these movement provides a way of evaluating the fetus.
Vibroacoustic Stimulation
Uses sound stimulation to elicit fetal movement.
May be able to confirm nonreactive NST findings.
Appears to be safe for fetus in terms of hearing at 33 weeks gestation or older.