What prenatal labs are done after pregnancy confirmation?

Standard Prenatal Laboratory Tests After Pregnancy Confirmation

After pregnancy confirmation, a comprehensive panel of prenatal laboratory tests should be performed at the first prenatal visit to screen for conditions that could affect maternal and fetal health, including blood type, infectious diseases, and genetic abnormalities. 1

First Trimester Laboratory Tests

Essential Screening Tests

• Complete Blood Count (CBC) - Screens for anemia and other hematologic conditions 1, 2
• Blood Type and Rh Status - Critical for planning prophylaxis for Rh-negative women 1
• Infectious Disease Screening:
  • Hepatitis B surface antigen (HBsAg) - Required to reduce risk of mother-to-child transmission 1, 3
  • HIV antibody testing - Universal screening recommended 1, 3
  • Syphilis serology - Required for all pregnant women 1, 3
  • Hepatitis C screening - For women with risk factors 1
  • Rubella antibody status - To identify susceptible women 2

Genetic Screening

• First Trimester Combined Screening (11-13+6 weeks):
  • Nuchal translucency (NT) measurement
  • Pregnancy-associated plasma protein A (PAPP-A)
  • Human chorionic gonadotropin (hCG) or free beta-hCG 1
• Cell-free DNA screening - Can be performed anytime after 10 weeks 1, 4
• Diagnostic testing options:
  • Chorionic villus sampling (CVS) - Available from 10-13 weeks 1
  • Amniocentesis - Available after 15 weeks 1

Additional First Trimester Tests

• Urinalysis - For protein and glucose screening
• Varicella antibody testing - For women with unknown history of chickenpox 2
• Chlamydia screening - Particularly important in high-risk populations 2
• Vitamin D levels - May be considered in at-risk populations 2

Second Trimester Tests (if not done in first trimester)

• Quadruple screening (15-20 weeks) - For neural tube defects and chromosomal abnormalities 1
• Gestational diabetes screening - After 24 weeks of gestation 1
• Group B Streptococcus (GBS) screening - At 35-37 weeks 2, 3

Important Considerations

• Timing is critical - delaying screening for conditions like hepatitis B can increase risk of mother-to-child transmission 1
• Missing Rh status can have critical implications for prophylaxis planning 1
• For women ≥35 years old, diagnostic testing should be offered due to increased risk of chromosomal abnormalities 1
• Twin pregnancies require additional considerations including determination of chorionicity and amnionicity 1

Common Pitfalls to Avoid

• Failing to document maternal disease status in medical records (now mandated by Joint Commission) 3
• Delaying screening beyond optimal windows for intervention
• Not performing immediate peripartum testing for women with inadequate prenatal screening 3
• Misinterpreting pregnancy test results - current tests can detect pregnancy as early as 3-4 days after implantation 5

Following this standardized approach to prenatal laboratory testing ensures comprehensive screening for conditions that could affect maternal and fetal health, allowing for timely interventions to improve outcomes.