Maternal / Prenatal Screening
Discovering the risks of a birth defect early in the pregnancy could help the patient and the doctor take informed decisions at the right time.
Did you know that you can now learn about the risks for genetic abnormalities as early as 1st Trimester? The detection rates are also getting better with the advent of new technologies. And, on top of all this, now you have multiple options to choose from.
These screening tests provide a safe and non-invasive method for pregnant women to learn about the risks of common genetic abnormalities. If you’re pregnant, a screening test can tell you early in the pregnancy about the risks of Downs Syndrome (Trisomy 21), Edwards Syndrome (Trisomy 18), Patau Syndrome (Trisomy 13) and a few others.
If the screening test indicates a higher risk, the patient can go for further diagnostic tests to get a definite answer.
Maternal Serum Screening
First Trimester Screening – Double Marker Test (10 to 13+6 weeks)
The parents and the doctors indeed want to know as early as possible about the possibility of genetic anomalies. The earliest window available for getting such information is between 9 to 14 weeks through the double market test and NT scan.
The double marker test is called so because it involves the analysis of two biochemical markers: Free Beta HCG1 and PAPP-A2. The ultrasound examination for Nucal Transluceny (NT) – the fluid accumulation at the base of the fetus’ neck, provides additional indication about the risk for down syndrome. The NT Scan is done between 11 to 14 weeks.
By combining the information from biochemical markers and the NT scan, the Combined First Trimester Screening test from AGILE provides a very reliable indication about the risks of Edward, Down and Patau Syndromes (Trisomy 13,18 & 21).
The First Trimester Screening presents significant advantages over other tests because of higher detection rates (90-95% with 5% false positive rates), and availability of information at an early stage of pregnancy.~(Reference: Fetal Medicine Foundation)
1. hCG: human chorionic gonadotropin
2. PAAP-A: pregnancy-associated plasma protein
Second Trimester Screening – Triple/Quad Test (16 to 21 weeks)
The Second Trimester Screening is done between 15th to 20th weeks of the pregnancy.The Triple and Quadruple tests offered as part of the second trimester screening provide an option to the couple who has missed the first trimester screening. The first trimester screening is preferable to second trimester screening due to its high sensitivity.
Triple Marker Test
The Triple Marker Test measures the levels of three important substances in the placenta: Alpha-fetoprotein (AFP), Human chorionic gonadotropin (HCG) and Unconjugated Estriol (uE3). The abnormal levels of these markers can detect the possibility of fetus having: Trisomy 13,18 or 21 and Open Neural Tube Defects (ONTD) such as Spinabifda, anencephaly etc.
Quadruple Marker Test
The Quadruple marker test combines the three markers of the triple marker test (AFP, hCG, uE3), along with an additional marker Inhibin-A. This test is useful in identifying the Trisomy 13, Trisomy 18, Trisomy 21 and Open Neural Tube Defects (ONTD).
Interpreting the Prenatal Screening Tests
The prenatal screening tests are meant to provide an early indication about the possibility of common genetic anomalies such as Down Syndrome or Trisomy 13, 18 etc. These tests typically compare the probability of a genetic defect vis-a-vis the age related risk. Maternal age is known to have a very well established correlation with several genetic disorders. However,advanced maternal age (mothers > 35 years) is no longer considered a definitive cut-off since many genetic abnormalities have been observed in mothers of much younger age.
The information available through screening tests helps classify the women into High Risk and Low Risk categories. These results need to be confirmed using confirmatory tests such as Karyotyping or Microarray.
The High Risk pregnant women are advised to undergo invasive diagnostic procedures like Amniocentesis or Chorionic Villus Sampling (CVS).
A low risk in the screening tests does not rule out the genetic abnormalities, and the gynaecologist or fetal medicine specialist may still advice an invasive diagnostic procedure depending upon the conditions of each specific case. In certain countries (e.g. USA), all women are offered the option of the invasive procedures.
Non Invasive Prenatal Screening (NIPS) (after 10 weeks)
Non Invasive Prenatal Screening (NIPS) also referred to as Non Invasive Prenatal Test (NIPT) is the latest addition to the options for Maternal Screening, and with much higher precision and sensitivity. NIPS uses the the cell-free DNA fragments (cfDNA) of the fetus, which are floating in maternal blood to detect fetal anomalites such as Trisomy 21, 13, 18 and few other common syndromes.
Using the massive parallel sequencing technology, NIPS provides far greater sensitivity and specificity as compared to the traditional biochemical screening methods (sensitivity of 99 %).
The AGILE Advantage
* AGILE Maternal Screening Program offers a wide range of technologies to choose from
* The Maternal Serum Screening tests are performed in accordance with the Fetal Medicine Foundation (FMF) and other international guidelines
* The reporting algorithms are fully validated and are in accordance with international standards and published literature
* Options for integrated and sequential screening
* AGILE screening programs are further linked with prenatal diagnostic options, providing additional convenience, confidence and guidance to doctors and patients.