Introduction

Current prenatal screening options include tests with sub-optimal sensitivity and specificity rates, while diagnostic procedures are invasive and carry with them a risk of procedure related miscarriage. There is a clear, unmet need for accurate, safe, prenatal diagnostic technologies that allow for early detection of fetal aneuploidies to provide more accurate information to pregnant women and their clinicians. Non-invasive prenatal testing provides a solution to this need.

Prenatal Testing Landscape^1-4

• 2.6 Million Maternal Serum Screens Performed Per Year
  1. 64% traditional 2^nd trimester screens (triple and quad marker screens)
  2. 16% 1^st trimester screens
  3. 20% 1^st trimester and 2^nd trimester combination screens (integrated, sequential)
• 200,000 Invasive Prenatal Diagnostic Procedures for Aneuploidy Detection per Year
  1. 156,000 amniocentesis for aneuploidy
  2. 44,000 chorionic villus sampling (CVS) procedures

Sources:

1. CDC National Vital Statistics (2009).
2. California Prenatal Screening Program presented data.
3. CAP Maternal Screening Participant Survey, 2011.
4. Invasive procedures estimated based on analysis of Thompson Reuters MarketScan 2009 commercial claims database.

CVS and Amniocentesis Risks^1-4

• Risks include about a 1 in 100 miscarriage rate for CVS procedures and between 1 in 300/500 for amniocentesis as well as infection and infection transmission.
• Studies have found that women awaiting amniocentesis experience a high state anxiety associated with modestly increased plasma cortisol.

Sources:

1. Available at: Mayo Clinic.
2. Mayo Clinic Complete Book of Pregnancy & Baby’s First Year. Johnson R et al. Ch. 6 and 11.
3. Williams Obstetrics Twenty-Second Cunningham, F. Gary et al. Ch. 13.
4. Maternal anxiety at amniocentesis and plasma cortisol. Sarkar P et al. Prenatal Diagnosis (2006); v26:505-509.

Medical Society Guidelines

ACOG Practice Bulletin #77¹
“The goal is to offer screening tests with high detection rates and low false-positive rates that also provide patients with the diagnostic options they might want to consider. Ideally, patients seen early in pregnancy should be offered aneuploidy screening that combines first- and second-trimester testing (integrated or sequential).”

Aneuploidy Screening

• “Ideally, all women should be offered aneuploidy screening before 20 weeks’ gestation, regardless of maternal age.”
• Physicians should assess which test best meets the needs of the patient; should provide information on detection and false positive rates, disadvantages and advantages, limitations, and the risks and benefits of each screening test and diagnostic procedure so that the patient can make an informed decision.

Aneuploidy Screening vs. Diagnostic Testing

• “Screening for aneuploidy identifies a population of women whose fetuses are at increased risk for Down syndrome, trisomy 18, or trisomy 13.”
• “If women who have had a positive screening result choose to undergo a diagnostic procedure such as CVS or amniocentesis, there is a higher chance of identifying an affected fetus than…if the diagnostic was performed in an unscreened population. Fewer invasive procedures will be required in patients who have screening, thus resulting in a decreased number of procedure-related losses of normal fetuses.”

Source:

1. Screening for Fetal Chromosomal Abnormalities (Joint with the Committee on Genetics and the Society for Maternal–Fetal Medicine) (Obstet Gynecol 2007;109:217–27). Available at: https://www.smfm.org/attachedfilesPubs/pb077.pdf