NCLEX Review Guide: Antepartum Diagnostic Testing

Purpose and Timing

• Antepartum diagnostic testing evaluates fetal well-being and maternal health during pregnancy to identify potential complications early.
• Testing is typically initiated based on risk factors such as maternal age >35, diabetes, hypertension, or previous pregnancy complications.

Screening Tests

• First trimester screening combines maternal serum markers (PAPP-A and free β-hCG) with nuchal translucency ultrasound at 11-13 weeks. This screening detects risk for chromosomal abnormalities like Down syndrome with 85% detection rate.
• Chorionic villus sampling (CVS) performed at 10-13 weeks provides definitive chromosomal diagnosis by sampling placental tissue, carrying a 1:300-500 miscarriage risk.

Diagnostic Procedures

• Amniocentesis performed at 15-20 weeks involves inserting a needle through the abdomen to sample amniotic fluid for chromosomal analysis. The procedure has a 1:300-500 miscarriage risk and requires informed consent.
• Quad screen (AFP, hCG, estriol, inhibin A) at 15-20 weeks screens for neural tube defects and chromosomal abnormalities with results reported as risk ratios.
• Anatomy ultrasound at 18-22 weeks evaluates fetal structures, placental location, amniotic fluid volume, and estimated fetal weight.

Amniocentesis Nursing Care

1. Obtain informed consent and verify gestational age
2. Position client supine with slight left lateral tilt
3. Monitor fetal heart rate before and after procedure
4. Instruct client to report cramping, bleeding, or fluid leakage
5. Administer RhoGAM if client is Rh-negative

Fetal Surveillance

• Non-stress test (NST) evaluates fetal heart rate response to fetal movement, with reactive results showing ≥2 accelerations of ≥15 bpm lasting ≥15 seconds in 20 minutes.
• Biophysical profile (BPP) combines NST with ultrasound assessment of fetal breathing, movement, tone, and amniotic fluid volume, scored 0-10 with ≥8 considered normal.
• Contraction stress test (CST) evaluates fetal response to uterine contractions, with negative results (no late decelerations) indicating adequate placental function.