Antenatal Testing
Purpose of antenatal testing (Why is it done?)
To assess fetal well-being, detect anomalies, obtain baseline information, and guide care
When can abdominal vs. vaginal ultrasound be used?
Abdominal after 1st trimester; vaginal is earlier and more accurate
What is Nuchal Translucency screening used for?
Detects risk for trisomy 13, 18, 21; performed at 11–14 weeks
Five components of a Biophysical Profile (BPP)
NST, fetal breathing, gross movements, fetal tone, amniotic fluid volume
What does the Non-Stress Test (NST) evaluate?
Fetal heart rate accelerations in response to fetal movement
Difference between screening and diagnostic tests
Screening identifies risk; diagnostic confirms or rules out a condition
What can ultrasound detect in the 1st trimester?
Gestational sac, embryo, cardiac activity, crown-rump length, placental position
What is Placental Grading and why is it important?
Grades 0–III; higher grades indicate placental aging and risk for hypoxia
Interpretation of a normal BPP score vs. abnormal
8–10 = reassuring; ≤6 = nonreassuring, possible compromise
Criteria for a Reactive NST
≥2 accelerations of 15 bpm for 15 sec within 20 min
Two types of antenatal testing methods
Invasive (e.g., amniocentesis, CVS, PUBS) vs. Noninvasive (e.g., ultrasound, NST)
What can ultrasound detect in the 2nd/3rd trimester?
Viability, fetal anatomy, placenta location, fetal weight, amniotic fluid volume, fetal position
What does Amniotic Fluid Index (AFI) measure?
Amniotic fluid volume;
<5 = oligohydramnios,
>24 = polyhydramnios
What does Fetal Fibronectin (fFN) indicate?
Presence between 20–34 weeks suggests risk of preterm labor within 2 weeks
Next step when an NST is non-reactive
Try vibroacoustic stimulation, extend monitoring; if still nonreactive → further testing
Key nursing care responsibilities during antenatal testing
Provide education, support, maintain safety, document, report results, and reinforce provider instructions
What does a Doppler blood flow study measure?
Perfusion/velocity of blood flow; S/D ratio to evaluate IUGR; abnormal if reversed or absent
Purpose of Amniocentesis in early vs. late pregnancy
Early (15–20 wks): chromosomal & biochemical studies;
Late (30–39 wks): lung maturity, infection, hemolytic disease
What is PUBS used for?
Percutaneous Umbilical Blood Sampling; detects chromosomal issues, hemolytic disease, congenital infection
What is the purpose of a Contraction Stress Test (CST)?
Evaluates placental oxygenation by monitoring fetal heart during contractions
Indications for antenatal testing
Maternal conditions (diabetes, HTN), decreased fetal movement, abnormal screening results, suspected growth restriction, post-term pregnancy
What is the significance of cervical length measurement?
>25 mm indicates low risk of preterm delivery within 14 days; <25 mm = risk; detects funneling
Difference between CVS and Amniocentesis
CVS (10–13 wks, detects genetic/DNA issues, not NTDs, risk of limb defects) vs Amniocentesis (15–20 wks, detects NTDs & lung maturity)
What four substances are measured in the Quad Screen?
AFP, hCG, estriol, inhibin A
Contraindications for a CST
Third-trimester bleeding, prior classical C-section, PROM, multiples, preterm labor risk