91% Detection Rate

5% False Positive Rate

The Data Demonstrates the Facts

In March, 2007 a meta-analysis was published in the Gray Journal (References) which supports this fact and crystallizes the essential message many obstetricians and labs already know. The final two sentences of the analysis summarize this point very well:

“Our data from an extensive meta-analysis demonstrates that free Beta hCG significantly improves the performance of first-trimester screening with PAPP-A/NT by increasing the sensitivity, lowering the false-positive rate, and achieving earlier diagnosis than total hCG. It is time to declare this debate finished and move on to nationwide implementation of the optimal protocol.”

Other key conclusions regarding the free Beta hCG/PAPP-A/NT protocol are as follows:

1. free Beta hCG detected 3 times the number of Down syndrome cases as total hCG in the 9-12 week range. There were greater than 10-fold more cases detected at the earliest gestations (i.e., 9-10 weeks).
2. free Beta hCG results in significantly lower false negative rates (i.e., the percentage of cases that were missed by the other markers) than total hCG.
3. free Beta hCG results in significantly lower false positive rates than total hCG at 9-12 weeks.
4 .free Beta hCG significantly reduces expected iatrogenic losses as compared with total hCG.
5. In younger patients (<35 years), detection of Down syndrome increased by 4, 5, 6 and 7 percentage points (at 9, 10, 11 and 12 weeks respectively) when free Beta hCG was used versus 0,0, 2 and 4 percentage points when total hCG was used.
6. In advanced maternal aged patients (> 35), inclusion of free Beta hCG reduced the false positive rate by 2.5, 3.1, 3.8 and 4.4 percentage points (at 9, 10, 11 and 12 weeks respectively) versus 0.1, 0.3, 1.0 and 2.2 percentage points when total hCG was used. References

To receive a copy of the meta-analysis findings, email us your request.

Ultra-Screen® Protocol

NTD Labs’ Ultra-Screen® protocol reliably assesses a mother’s risk for Down syndrome and trisomy 18/13 in the first trimester. Performed between 11 weeks, 1 day and 13 weeks, 6 days gestation, the Ultra-Screen protocol uses data from a blood screen (biochemistry) and an ultrasound examination (biophysical) which yields a risk assessment that physicians may present to their patients during the first trimester.

A maternal dried blood sample is analyzed for two biochemical markers: free Beta human chorionic gonadotropin (free Beta hCG) and pregnancy associated plasma protein-A (PAPP-A). Blood specimens are collected one of two ways, through a simple finger stick method, or with venipuncture. The venous blood is immediately spotted onto a dried blood test card provided by NTD Labs.

The ultrasound examination confirms the fetus’ gestational age and measures nuchal translucency (NT), the fluid accumulation behind the fetus’ neck. These combined biochemical and biophysical markers yield the most sensitive screening results possible at the earliest point during the pregnancy, with a 91% detection rate and 5% false positive rate for Down syndrome (95% detection, 0.3% false positive for trisomy 18/13). When a Fetal Nasal Bone Assessment is added to the protocol, the detection rate for Down syndrome increases to 95% with a false positive rate of just 2%. (References)

Primary benefits of the Ultra-Screen protocol:

  • 91% detection rate, 5% false positive rate for Down syndrome (95% detection rate, 0.3% false positive rate for trisomy 18/13
  • Safe, simple, non-invasive
  • 95% of all patients are shown to be at low risk for Down syndrome which means early reassurance for the vast majority
  • Those shown to be at risk can receive immediate counseling regarding possible follow-up options such as CVS (chorionic villus sampling) and amniocentesis
  • Reduces the number of missed cases
  • Separate twin reports
  • Separate interpretations for Down syndrome and trisomy 18/13
  • Reduces the potential for iatrogenic losses

The advantages of free Beta hCG:

The use of free Beta hCG in determining Down syndrome and other chromosomal abnormalities during the first trimester has been demonstrated to be more effective than other markers, including intact or total Beta hCG. Intact/total Beta hCG, while an effective second trimester marker, is not considered effective during the first trimester. Laboratories that lack the technology to measure free Beta hCG have attempted to use total Beta hCG as part of their first trimester screening. This practice results in significantly higher false positive rates for Down syndrome as compared to protocols that measure free Beta hCG. References

Dried Blood Advantages:

Logistical:

  • No centrifugation or refrigeration necessary
  • Eliminates possibility of broken sample tubes during transport
  • Reduces biohazard risk
  • Raises reporting reliability – blood sample, NT measurement and patient information
    are provided on one card

Analytical:

  • Stabilization of serum proteins
  • Reduced analyte standard deviation