CellFree DNA Prenatal Screen

• The Cell-Free DNA Prenatal Screen assesses the copy number state for ALL 46 chromosomes, which allows for evaluation of both common aneuploidies (trisomy 13, 18, 21) and rare autosomal aneuploidies.
• This screen does not provide diagnostic information. False-positive and/or false-negative results are possible. Thus, individualized patient-provider discussion is highly recommended prior to ordering, and clinical correlation is recommended for all results. Diagnostic testing should be offered to confirm screening results prior to any medical management decisions.
• This screen is validated for individuals with a singleton or twin pregnancy of at least 10 weeks gestation and does not assess for neural tube defects.
• Medical factors of the pregnant individual and/or chromosomal mosaicism in the placenta, the fetus(es), or the pregnant individual may impact results.
• There are several differences in the information available from this screening test in singletons compared to twins:
  
  • Aneuploidy of the X or Y chromosome is evaluated only in a singleton pregnancy. It is not evaluated in twins.
  • Evaluation of both sex chromosomes is available upon request in singleton pregnancies. In twin pregnancies, evaluation for the presence of a Y chromosome is available upon request. If Y chromosome material is detected in a twin gestation, this screen cannot distinguish whether it is present in one or both fetuses.
  • Positive screening results in twin gestations cannot resolve whether one or both fetuses are at risk.

Ordering Requirements

Singleton and twin pregnancies
For orders submitted electronically via Epic, providers must complete the clinical questions in the order.

Submissions from outside (reference lab) clients must be accompanied by a completed UW Genetics Clinical Lab Request form.

This screen is not validated for triplets or higher order multiple gestations.

Two 10 mL whole blood in Streck Cell-Free DNA BCT® tubes (mottled black and tan).

Gently mix blood by inverting tube 8-10 times.

Do not send samples via pneumatic tube system. Samples collected in Streck tubes must be walked to the laboratory.

Store whole blood at room temperature. Do not freeze. For orders not placed in Epic, a completed UW Genetics Clinical Lab Request form is required.

At the cfDNA Panel (PDNAP) prompt:

• Singleton:
  • Enter PSFULL for Full prenatal screen for all 46 chromosomes, autosomes PLUS sex chromosome aneuploidies.
  • Enter PSAU for Limited prenatal sreen for autosomes ONLY.
• Twin:
  • Enter PTFULL for Full prenatal screen for all 46 chromosomes, autosomes PLUS presence of Y chromosome.
  • Enter PTAU for Limited prenatal screen for autosomes WITHOUT the Y chromosome.

Stability: Ambient, 5 days.