Patient FAQs

Why should First Trimester Screen | Fß be offered to all pregnant women?

Patients are becoming increasingly sophisticated in their knowledge of risk assessment options, with study after study indicating that the vast majority of patients prefer to know their risk of having a fetus with Down syndrome during their first trimester. With the First Trimester Screen | Fß test from NTD, physicians can provide patients with the standard of care in first trimester Down syndrome screening. This simple, non-invasive procedure enables a quick, efficient, reliable assessment of a patient’s risk for having a fetus with Down syndrome, providing detection rates as high as 95% and false positive rates as low as 2% when an optional fetal nasal bone assessment is included. (References 25)

What exactly is measured with the First Trimester Screen | Fß test?

The First Trimester Screen | Fß test measures biophysical and biochemical markers. The biophysical markers include nuchal translucency (NT), measured during a routine ultrasound examination. An optional fetal nasal bone assessment may be added to the test to measure the presence or absence of the fetal nasal bone. The biochemical markers measured from a simple, safe maternal blood specimen are free Beta human Chorionic Gonadotropin (hCG) and pregnancy associated plasma protein-A (PAPP-A). The protocol combines the data from the blood screen with the information obtained during the NT ultrasound measurement to calculate an individual risk assessment for Down syndrome and trisomy 18 and 13.

The advantages of the First Trimester Screen | Fß test include:

  • 91% detection rate at a 5% false positive rate in the first trimester (References 13)
  • Patients shown to be at risk have added time to consider follow-up diagnostic procedures such as Chorionic Villus Sampling (CVS) or amniocentesis

With the addition of an optional Fetal Nasal Bone Assessment, the detection rate increases to 95% at a 2% false positive rate. Data from 18,000 patients in 12 investigational studies indicates that the nasal bone is absent in approximately 70% of Down syndrome cases and just 1.5% of unaffected cases in the first trimester of pregnancy. (References 25)

What are the advantages of the First Trimester Screen | Fß test?

  • For those shown to be at low risk, First Trimester Screen | Fß reduces the use of unnecessary diagnostic procedures that increase certain health risks to the patient and fetus
  • For those shown to be at higher risk, First Trimester Screen | Fß gives the patient and physician more time to consider follow-up diagnostic testing options such as CVS or amniocentesis
  • The test is safe, simple and non-invasive, so patients are more likely to undergo this screening
  • Provides separate twin results reports
  • Provides separate trisomy 18 and 13 results

Why is the First Trimester Screen | Fß test more effective?

Free beta hCG and PAPP-A are considered to be effective markers for Down syndrome, detecting approximately 60-65% of Down syndrome cases. With the inclusion of an ultrasound examination for nuchal translucency, the combined protocol offers a 91% detection rate for Down syndrome at a 5% false positive rate. (References 13)

Why is total hCG not an effective first trimester biomarker?

Total hCG is not an effective first trimester biomarker for Down syndrome. To maximize the inherent benefits of first trimester screening, free Beta hCG must be used instead of total hCG. (References 27,28)

Laboratories that lack the technology to measure free beta hCG may attempt to use total hCG during the first trimester. However, free beta hCG and total hCG are not the same. Make sure you are receiving the protocol used in the BUN and FaSTER studies sponsored by the NIH.

What sort of follow-up testing can I receive if the results show an increased risk?

When First Trimester Screen | Fß risk assessments indicate that a patient is at increased risk for Down syndrome or trisomy 18 or 13, health care professionals often recommend one of two types of follow-up diagnostic tests to confirm the presence of birth defects or chromosomal abnormalities, CSV or amniocentesis. Both CVS and amniocentesis carry a small risk of complications, including miscarriage.

Chorionic Villus Sampling (CVS)
Performed in the first trimester of pregnancy, CVS involves the withdrawal of a small amount of chorionic tissue from the placenta. This tissue is then cultured and a chromosome analysis (a karyotype) is performed.

Amniocentesis
Typically performed between 15-20 weeks of pregnancy, amniocentesis involves a small amount of amniotic fluid being withdrawn from the uterus. The fluid is then sent to a lab, where a chromosome analysis (a karyotype) is performed.

Does the First Trimester Screen | Fß test screen for open neural tube defects?

Although the First Trimester Screen | Fß protocol represents the best first trimester screening option for Down syndrome and trisomy 18 and 13, it does not screen for open neural tube defects (ONTDs). Therefore, it is highly recommended that patients undergo maternal serum AFP (MSAFP) screening for ONTDs during the second trimester of pregnancy.

What are the advantages of dried blood spot sampling?

NTD Labs utilizes a patented dried blood spot sampling technique that is simple and safe.  Maternal blood specimens are spotted onto an absorbent filter paper using a simple finger stick method that can be performed in a physician’s office or in a testing lab, or at home by the patient using a home collection kit. No phlebotomist is required. Practices may continue to use venous blood and a Diff-Safe device if they prefer, however some of the logistical issues may be lost such as:

  • Simple, safe collection and transport
  • Reduced biohazard risk
  • Patient convenience, no extra trip to the blood drawing station required

NTD Labs' dried blood spot sampling also enhances the reliability of the data and reduces the risk of case file errors since patient demographics; ultrasound information and blood collection are all entered onto a single form.

How much scientific evidence is there to support the use of the First Trimester Screen | Fß test for Down syndrome screening?

There is a large body of evidence to support the First Trimester Screen | Fß test as the standard of care in first trimester Down syndrome screening. The efficacy of NTD’s patented First Trimester Screen | Fß protocol for first trimester screening utilizing NT ultrasound measurements and 2 biochemical markers – free Beta hCG and PAPP-A - has been proven in 23 population-based studies examining over 260,000 patients, as well as 2 NIH-sponsored clinical trials. (References)