noninvasive prenatal screening and maternal serum screening · (part 1 and part 2) (mayo id:...

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MATERNAL SERUM SCREENING Maternal serum screening is used in obstetric care to identify pregnancies that may have an increased risk for certain birth defects such as trisomy 21 (Down syndrome), trisomy 18, and open neural tube defects. These screening methods assess risk of fetal defects by measuring biochemical markers in maternal serum and in some cases also incorporate fetal nuchal translucency measurements obtained through sonography. Although a positive screen is not a diagnosis, pregnancies at higher risk are identified, and these patients can be offered diagnostic testing. Multiple screening options are available, including first trimester screening, second trimester screening, and cross-trimester screening. Cross-trimester screening has an improved detection rate and a decreased false positive rate as compared to either first or second trimester screening alone as this screening method incorporates markers from both trimesters in the risk calculation. CELL-FREE DNA SCREENING More recently, an alternative screening method has emerged that measures risk by assessing fetal cell-free DNA in maternal serum. This screening method, which has been rapidly adopted, offers higher sensitivity and specificity for trisomy 21 and 18 than biochemical maternal screening methods and can be used as early as 10 weeks gestation. Cell-free DNA screening can also detect other aneuploidies including trisomy 13; it does not, however, detect open neural tube defects. This method of screening, frequently referred to as noninvasive prenatal screening, is also not diagnostic, and follow up with diagnostic testing for positive screens is recommended. ACOG GUIDELINES The 2007 American Congress of Obstetricians and Gynecologists (ACOG) Screening for Fetal Chromosomal Abnormalities Practice Bulletin recommends that all women should be offered aneuploidy screening before 20 weeks of gestation, regardless of maternal age. Ideally, for women who present early in pregnancy, a strategy that incorporates both first and second trimester screening should be offered. The 2015 ACOG Committee Opinion for Cell-Free DNA Screening for Fetal Aneuploidy reiterates this recommendation of providing counseling to all women and discussing the risks and benefits of the available screening methods. This committee opinion states that any patient may choose cell-free DNA screening; however, conventional maternal screening methods are the most appropriate choice for low-risk pregnancies. MAYOMEDICALLABORATORIES.COM 800-533-1710 OR +507-266-5700 Improving Patient Outcomes: Which test is best for your patient? NONINVASIVE PRENATAL SCREENING AND MATERNAL SERUM SCREENING

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Page 1: NONINVASIVE PRENATAL SCREENING AND MATERNAL SERUM SCREENING · (Part 1 and Part 2) (Mayo ID: SEQU/SEQF) Alpha-Fetoprotein, Single Marker, Maternal Screen (Mayo ID: MAFP) DESCRIPTION

MATERNAL SERUM SCREENING Maternal serum screening is used in obstetric care to identify pregnancies that may have an increased risk for certain birth defects such as trisomy 21 (Down syndrome), trisomy 18, and open neural tube defects. These screening methods assess risk of fetal defects by measuring biochemical markers in maternal serum and in some cases also incorporate fetal nuchal translucency measurements obtained through sonography. Although a positive screen is not a diagnosis, pregnancies at higher risk are identified, and these patients can be offered diagnostic testing. Multiple screening options are available, including first trimester screening, second trimester screening, and cross-trimester screening. Cross-trimester screening has an improved detection rate and a decreased false positive rate as compared to either first or second trimester screening alone as this screening method incorporates markers from both trimesters in the risk calculation.

CELL-FREE DNA SCREENING More recently, an alternative screening method has emerged that measures risk by assessing fetal cell-free DNA in maternal serum. This screening method, which has been rapidly adopted, offers higher sensitivity and specificity for trisomy 21 and 18 than biochemical maternal screening methods and can be used as early as 10 weeks gestation. Cell-free DNA screening can also detect other aneuploidies including trisomy 13; it does not, however, detect open neural tube defects. This method of screening, frequently referred to as noninvasive prenatal screening, is also not diagnostic, and follow up with diagnostic testing for positive screens is recommended.

ACOG GUIDELINES The 2007 American Congress of Obstetricians and Gynecologists (ACOG) Screening for Fetal Chromosomal Abnormalities Practice Bulletin recommends that all women should be offered aneuploidy screening before 20 weeks of gestation, regardless of maternal age. Ideally, for women who present early in pregnancy, a strategy that incorporates both first and second trimester screening should be offered. The 2015 ACOG Committee Opinion for Cell-Free DNA Screening for Fetal Aneuploidy reiterates this recommendation of providing counseling to all women and discussing the risks and benefits of the available screening methods. This committee opinion states that any patient may choose cell-free DNA screening; however, conventional maternal screening methods are the most appropriate choice for low-risk pregnancies.

M A Y O M E D I C A L L A B O R A T O R I E S . C O M 8 0 0 - 5 3 3 - 1 7 1 0 O R + 5 0 7 - 2 6 6 - 5 7 0 0

Improving Patient Outcomes: Which test is best for your patient?

NONINVASIVE PRENATAL SCREENING AND MATERNAL SERUM SCREENING

Page 2: NONINVASIVE PRENATAL SCREENING AND MATERNAL SERUM SCREENING · (Part 1 and Part 2) (Mayo ID: SEQU/SEQF) Alpha-Fetoprotein, Single Marker, Maternal Screen (Mayo ID: MAFP) DESCRIPTION

MC6765-07rev0516

NONINVASIVE PRENATAL SCREENING

MATERNAL SERUM SCREENING

TEST NAME Cell-Free DNA Prenatal Screen(Mayo ID: NIPS)

First Trimester Maternal Screen(Mayo ID: 1STT)

QUAD Screen (Second Trimester) Maternal(Mayo ID: QUAD)

Sequential Maternal Screen (Part 1 and Part 2)(Mayo ID: SEQU/SEQF)

Alpha-Fetoprotein, Single Marker, Maternal Screen(Mayo ID: MAFP)

DESCRIPTION First or second trimester screen using cell-free DNA analysis.

First trimester screen using NT and biochemical markers.

Second trimester screen using biochemical markers.

Cross-trimester screen using NT and biochemical markers.

First trimester results provided only if positive, otherwise combined risk provided after second trimester screen.

Second trimester screen using single biochemical marker for NTD only.

SCREENS FOR Trisomy 21

Trisomy 18

Trisomy 13

Gender

Trisomy 21

Trisomy 18

Trisomy 21

Trisomy 18

Open NTD

Trisomy 21

Trisomy 18

Open NTD (If Part 2 is completed)

Open NTD

GESTATIONAL AGE (IN WEEKS)

10, 0 and up 10, 0 to 13, 3 (by CRL) T21/T18: 14, 0 to 22, 6

NTD: 15, 0 to 22,6

Part 1: 10, 0 to 13, 3 (by CRL)

Part 2: 15, 0 to 22, 6

15, 0 to 22, 6

MARKERS Cell-free DNA, chromosomes 21, 18, 13, and Y

PAPP-A

hCG (total)

NT

AFP

uE3

hCG (total)

inhibin

Part 1:

PAPP-A

NT

Part 2:

AFP

uE3

hCG (total)

inhibin

AFP

FALSE POSITIVE RATES FOR MAYO CLINIC VALIDATED TESTS

Trisomy 21: 0.09%

Trisomy 18: 0.13%

Trisomy 13: 0.13%

Trisomy 21: 5–10%

Trisomy 18: <1%

Trisomy 21: 6–7%

Trisomy 18: <1%

Open NTD: 2%

Trisomy 21: Part 1&2: 3–4%

Trisomy 18: Parts 1&2: <1%

Open NTD: Part 2: 2%

Open NTD: 2%

PROS Lowest false positive rate

Early results

Does not require NT measurement

Early results Includes trisomy and NTD screening

Does not require NT measurement

High-risk results available in first trimester

High detection rate with combined risk assessment

Single marker screen for NTD

Can complement first trimester screening or cfDNA screening

CONS Requires separate follow-up for NTD

Requires separate follow-up for NTD

Requires NT measurement by certified sonographer

Results not available until 2nd trimester

For most women, results not available until 2nd trimester

Requires NT measurement by certified sonographer

Requires coordination of two samples

Risk assessment limited to NTD

Abbreviations: AFP – alpha-fetoprotein; CRL – crown-rump-length; CVS – chorionic villus sampling; DS – Down syndrome; hCG – human chorionic gonadotropin; NT – nuchal translucency; NTD – neural tube defect; PAPP-A – pregnancy associated plasma protein A; uE3 – unconjugated estriol.