DESCRIPTION
Definitive diagnosis of Down syndrome and other chromosomal abnormalities requires amniocentesis or chorionic villus sampling (CVS), both of which are invasive procedures that carry a risk of miscarriage estimated at 0.5% to 1%. Less invasive screening programs have been developed with the use of biochemical markers and ultrasound that show an association with Down syndrome.
First trimester screening for Down syndrome may include measurement of nuchal translucency (ultrasound detection of subcutaneous edema in the fetal neck) combined with maternal serum assessment including free beta subunit of human chorionic gonadotropin (β-hCG) or total human chorionic gonadotropin (hCG), along with pregnancy-associated plasma protein-A [PAPP-A]. Cell-free DNA testing may also be performed. A specific risk estimate is calculated using these results as well as maternal factors such as maternal age, prior history, weight, race, and number of fetuses. Measurement of nuchal translucency alone is less effective for first-trimester screening than the combined testing.
Another potential ultrasound marker is fetal nasal bone examination. The technique for assessing the nasal bone using ultrasound involves viewing the fetal face longitudinally and exactly in the midline. The nasal bones are considered to be present if the line within the bridge of the nose is more echogenic than the overlying skin and absent if the echogenicity is the same or less than the skin, or if it is not visible. The absence of fetal nasal bone is considered a positive test result, indicating an increased risk of Down syndrome.
POLICY
First-trimester screening for detection of Down syndrome incorporating maternal serum assessment and measurement of fetal nuchal translucency may be considered medically necessary if the medical appropriateness criteria are met. (See Medical Appropriateness below.)
First-trimester screening for detection of Down syndrome using measurement of nuchal translucency alone is considered investigational.
First-trimester screening for detection of Down syndrome using fetal nasal bone assessment translucency is considered investigational.
MEDICAL APPROPRIATENESS
First-trimester screening for detection of Down syndrome is considered medically appropriate if ALL of the following are met:
Screening includes measurement of fetal nuchal translucency with ANY ONE of the following:
Maternal serum markers (free beta subunit of human chorionic gonadotropin [β-hCG] or total human chorionic gonadotropin (hCG), and pregnancy-associated plasma protein-A [PAPP-A])
Maternal plasma using cell-free fetal DNA (cffDNA) with singleton pregnancy
IMPORTANT REMINDERS
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We develop Medical Policies to provide guidance to Members and Providers. This Medical Policy relates only to the services or supplies described in it. The existence of a Medical Policy is not an authorization, certification, explanation of benefits or a contract for the service (or supply) that is referenced in the Medical Policy. For a determination of the benefits that a Member is entitled to receive under his or her health plan, the Member's health plan must be reviewed. If there is a conflict between the medical policy and a health plan or government program (e.g., TennCare), the express terms of the health plan or government program will govern.
ADDITIONAL INFORMATION
There is insufficient evidence on the performance of fetal nasal bone assessment to determine its impact on health outcomes. Additional studies are needed before conclusions can be drawn about its utility.
SOURCES
Alldred, S.K., Takwoingi, W., Guo, B., Pennant, M., Deeks, J.J., Neilson, J.P., et al. (2017). First trimester ultrasound tests alone or in combination with first trimester serum tests for Down's syndrome screening. The Cochrane Database of Systematic Reviews, 3 (3), doi: 10.1002/14651858.CD012600. (Level 2 evidence)
American College of Medical Genetics and Genomics. (2016). Noninvasive prenatal screening for fetal aneuploidy, 2016 update: Position statement of the American College of Medical Genetics and Genomics. Retrieved May 27, 2021 from https://www.acmg.net/.
American College of Obstetricians and Gynecologists. ACOG Practice Bulletin Number 175. (2016, December; reaffirmed 2022). Ultrasound in pregnancy. Retrieved August 31, 2023 from http://www.acog.org/.
American College of Obstetricians and Gynecologists. ACOG Practice Bulletin Number 226. (2016, May; reaffirmed 2020). Screening for fetal chromosomal abnormalities. Retrieved August 31, 2023 from http://www.acog.org/.
American College of Obstetricians and Gynecologists, Committee on Genetics; Society of Maternal-Fetal Medicine. (2015, September). Cell-free DNA Screening for fetal aneuploidy. Committee opinion number 640. Retrieved August 7, 2015 from http://www.acog.org.
American College of Obstetricians and Gynecologist, Obstetric Care Consensus Number 11. (2022, August) Pregnancy at age 35 years or older. Retrieved August 31, 2023 from http://www.acog.org/.
Liu, Y., Ye, X., Zhang, N., Zhang, B., Guo, C., Huang, W., Jing, L., et al. (2015). Diagnostic value of ultrasonographic combining biochemical markers for Down syndrome screening in first trimester: a meta-analysis. Prenatal Diagnosis, 35 (9), 879-887. Abstract retrieved November 12, 2015 from PubMed database.
National Institute for Health and Clinical Excellence. (2021, August). Antenatal care. Retrieved August 31, 2023 from http://www.nice.org.uk.
Prats, P., Rodriguez, I., Comas, C., & Puerto, B. (2014). Systematic review of screening for trisomy 21 in twin pregnancies in first trimester combining nuchal translucency and biochemical markers: a meta-analysis. Prenatal Diagnosis, 34 (11), 1077-1083. Abstract retrieved November 12, 2015 from PubMed database.
ORIGINAL EFFECTIVE DATE: 9/11/2011
MOST RECENT REVIEW DATE: 10/12/2023
ID_BT
Policies included in the Medical Policy Manual are not intended to certify coverage availability. They are medical determinations about a particular technology, service, drug, etc. While a policy or technology may be medically necessary, it could be excluded in a member's benefit plan. Please check with the appropriate claims department to determine if the service in question is a covered service under a particular benefit plan. Use of the Medical Policy Manual is not intended to replace independent medical judgment for treatment of individuals. The content on this Web site is not intended to be a substitute for professional medical advice in any way. Always seek the advice of your physician or other qualified health care provider if you have questions regarding a medical condition or treatment.
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