NTD Laboratories, Inc.
403 Oakwood Road
Huntington Station, NY 11746
Phone: 1.888.NTDLABS (683.5227)
ntdlabs@perkinelmer.com
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NTD Laboratories, Inc.
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A second trimester test consisting of AFP, hCG, inhibin and Unconjugated estriol. The test can detect about 70% of Down Syndrome cases with an expected false positive rate of 5%. Some studies have observed a false positive rate significantly higher than 5%.
A follow-up test to the Ultra-Screen® test. The first trimester test can detect 90% of Down Syndrome pregnancies with a 5% false positive rate. In sequential testing both first trimester screening and Quad screening are performed. Although this procedure enables the detection a small percentage of additional cases, it can double the overall false positive rate to close to 10%. Screening tests should not be followed by additional screening tests but rather should be followed by diagnostic testing.
A screening procedure in which both first and second trimester screening are performed. However, the first trimester screening results are not provided to the physician and patient but are withheld until after the results of second trimester screening are available. Physicians should also be aware that many laboratories offering this protocol are using a Down Syndrome risk cut-off of 1 in 100. As a result patients at moderately increased risk will not be offered the option of amniocentesis with this protocol. Further, physicians should be aware that some patients will not undergo second trimester screening and could have no final Down Syndrome screening results.
A screening procedure similar to the integrated test except the ultrasound component of first trimester screening is not performed. This protocol has all of the disadvantages of the integrated test and is not as effective. This protocol was suggested during the early stages of first trimester screening when few centers were trained to offer the nuchal translucency evaluation. However, there are now a large number of centers offering nuchal translucency screening thus obviating the need for this alternative approach. The first trimester screen can provide all of the detection and false positive rates as the serum integrated test but at a much earlier point in pregnancy.
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