Should I undergo the Panorama test or nuchal translucency (NT) scan for early maternal screening?

Early Maternal Screening: Panorama vs Nuchal Translucency

Both Panorama (cell-free fetal DNA) and nuchal translucency (NT) with first trimester combined screening are acceptable options, but ACOG explicitly states that no single screening test is superior to another in all test characteristics, so the choice depends on timing, cost considerations, and what additional information you want beyond aneuploidy screening. 1

Key Decision Points

If Choosing Nuchal Translucency Combined Screening:

• Yes, put in the referral to fetal assessment NOW - NT must be performed between 11+0 to 14+0 weeks of gestation, as the measurement loses predictive value outside this narrow window 2, 3
• The patient will need two bloodwork requisitions for PAPP-A and free beta-hCG (or intact hCG) to be drawn during the same 11-14 week timeframe 1
• First trimester combined screening (NT + serum markers) detects approximately 90% of affected pregnancies with a 5% false-positive rate 1

Important Advantages of NT Combined Screening:

• Provides early reassurance and timely detection with the option for earlier and safer pregnancy termination if abnormalities are found 1
• Identifies structural abnormalities that cell-free DNA cannot detect - approximately 34% of congenital abnormalities in fetuses with increased NT would be missed if only cfDNA screening is used 4
• Detects genetic syndromes like Noonan syndrome and 22q11.2 deletion syndrome that Panorama will miss 2
• Particularly useful for twin gestations where each fetus can be assessed individually 1

If Choosing Panorama (Cell-Free Fetal DNA):

• Higher detection rate for trisomy 21 specifically, but only screens for trisomies 21,18,13, and sex chromosome aneuploidies 2
• Does not require the strict 11-14 week timing that NT does
• Costs $400 as mentioned, versus NT combined screening which may be covered differently by insurance
• Critical limitation: Will miss structural heart defects, skeletal dysplasias, other genetic syndromes, and chromosomal abnormalities beyond the common trisomies 2, 4

Important Caveats

Do NOT Skip Anatomic Survey:

• Even with negative Panorama results, a second trimester anatomic survey at 18-22 weeks is still required 2
• NT screening should never replace the standard second trimester anatomic fetal survey 1

Quality Assurance Matters for NT:

• NT measurement has considerable inter- and intra-observer variability, so ensure the facility participates in quality assurance programs like the Fetal Medicine Foundation or Nuchal Translucency Quality Review 1

If NT is Increased (≥3 mm):

• Immediate genetic counseling and invasive diagnostic testing should be offered 2, 3
• About one-third of fetuses with NT ≥3 mm will have chromosomal abnormalities 2, 3
• Fetal echocardiography at 18-22 weeks is indicated even if karyotype is normal, as cardiac defects remain elevated risk 2

Practical Algorithm

For patients presenting before 12 weeks:

• Offer both options with counseling about detection rates and limitations
• If NT chosen → place fetal assessment referral immediately + order both bloodwork requisitions for 11-14 week window
• If Panorama chosen → can be done more flexibly, but counsel that second trimester anatomy scan is still mandatory

For patients presenting at 12-13 weeks:

• NT combined screening is still feasible but time-sensitive - refer urgently 2, 3

For patients presenting after 14 weeks:

• NT is no longer an option; offer second trimester serum screening or cfDNA 1