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DESCRIPTIONUltrasound markers can potentially increase the sensitivity of biochemical measures for first trimester detection of Down syndrome. Nuchal translucency (NT) refers to the ultrasound detection of subcutaneous edema in the fetal neck between weeks 10 and 13 of gestation. Fetal nasal bone examination involves ultrasound assessment at 11-14 weeks’ gestation to identify the presence or absence of the nasal bone.
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%. Because of this risk, before biochemical screening existed, diagnosis was generally only offered to women 35 years or older, for whom the risk of the procedure approximated the risk of Down syndrome. However, the majority of babies with Down syndrome are born from mothers younger than 35 years, even though the mothers are at lower individual risk. This situation created interest in developing less-invasive screening programs based on assessment of serum markers that have shown associations with Down syndrome. In the late 1980s, biochemical screening at 16 weeks' gestation was developed and began to be offered to all pregnant women. Biochemical screening consists of maternal serum measurements of alpha-fetoprotein, human chorionic gonadotropin, and unconjugated estriol (i.e., triple screen). More recently, there has been the option of a fourth marker, inhibin-A (quadruple screen). The triple screen identifies approximately 69% of Down syndrome pregnancies and the quadruple screen 81%, both at a 5% false-positive rate. This false-positive rate refers to the proportion of all tests administered that are falsely positive at the cutoff point that produces that particular value of sensitivity. Among women who test positive, only about 2% actually have a fetus with Down syndrome.
There has also been interest in ultrasound markers to improve the accuracy of biochemical screening. One potential marker is fetal nuchal translucency. This refers to the ultrasound detection of subcutaneous edema in the fetal neck, and is measured as the maximal thickness of the sonolucent zone between the inner aspect of the fetal skin and the outer aspect of the soft tissue overlying the cervical spine or the occipital bone. In the early 1990s, screening studies of pregnant women reported an association between increased nuchal translucency in the first trimester of pregnancy (10–13 weeks of gestation) and chromosomal defects, most commonly Down syndrome, but also trisomy 18 and 13. Nuchal translucency could be done alone as a first-trimester screen, or in combination with the maternal serum markers free beta subunit of human chorionic gonadotropin (B-hCG) and pregnancy-associated plasma protein-A (PAPP-A). These are different serum markers than those used in the second-trimester triple or quadruple screen.
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 bone synostosis resembles a thin echogenic line within the bridge of the nose. The nasal bones are considered to be present if this line 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 to be a positive test result, indicating an increased risk of Down syndrome. In some cases, the sonographer will not be able to visualize the nasal area of the fetus’s face and thus cannot make a determination of the presence or absence of nasal bone. The inability to visualize the nasal bone is regarded as an unsuccessful examination rather than a positive test result. Fetal nasal bone examination can be done from 11 weeks to just before 14 weeks’ gestation. It is sometimes recommended that, if the nasal bone is absent on ultrasound done between 11 and 12 weeks’ gestation, a second examination be done one week later. Fetal nasal bone assessment can be done along with nuchal translucency, or in the second step of a two-stage screen for cases that are borderline using other first-trimester markers.
First-trimester screening, if accurate, can provide important information to the mother several weeks before it would be available with traditional second-trimester screening.
POLICYFirst-trimester screening for detection of Down syndrome incorporating maternal serum markers and measurement of fetal nuchal translucency may be considered medically necessary for women who are adequately counseled and desire information on the risk of having a child with Down syndrome.
First-trimester screening for detection of Down syndrome using measurement of nuchal translucency alone is investigational.
First-trimester screening for detection of Down syndrome incorporating fetal nasal bone assessment translucency is investigational.
POLICY GUIDELINESInvestigative service is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized by certifying boards and/or approving or licensing agencies or published peer review criteria as standard, effective medical practice for the treatment of the condition being treated and as such therefore is not considered medically necessary.
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.
POLICY HISTORY7/2003: Approved by Medical Policy Advisory Committee (MPAC)
7/15/2005: Reviewed by MPAC, status changed from investigational to covered during first-trimester when ultrasonic measurement of fetal nuchal translucency is used in conjunction with maternal age and other specified tests to detect Down syndrome. First-trimester screening for detection of Down syndrome using measurement of nuchal translucency alone is investigational.
10/17/2005: Code Reference table reviewed; table changed from non-covered to covered. Description of code 76999 revised.
1/29/2007: Code Reference section reviewed. CPT code 76999 and ICD-9 code 758.0 deleted. ICD-9 codes V23.81, V23.82, V26.31-V26.33, and V28.3 added. CPT codes 76813, 76814, 84163, and 84702 added. HCPCS code S3618 added with effective date 4-1-2007
3/29/2007: Policy reviewed, description updated, no change to policy statement
12/17/2007: Coding updated. CPT/HCPCS 2008 revision added to policy
5/1/2008: Policy reviewed, no changes
9/22/2008: Annual ICD-9 updates effective 10-1-2008 applied
08/03/2010: Policy title changed from “First-Trimester Detection of Down Syndrome Using Fetal Ultrasound Assessment of Nuchal Translucency Combined with Maternal Serum Assessment” to “First-Trimester Detection of Down Syndrome Using Fetal Ultrasound Markers Combined with Maternal Serum Assessment.” Policy description rewritten based on new research findings. The scope of the policy was expanded to include fetal nasal bone assessment. Investigational policy statement added regarding fetal nasal bone assessment.
06/13/2011: Policy review; no changes.
04/26/2012: Policy review; no changes.
12/21/2012: Added the following new 2013 CPT codes to the Code Reference section: 81508, 81509, 81510, 81511, and 81512.
08/07/2013: Policy reviewed; no changes.
SOURCESBlue Cross Blue shield Association policy # 4.01.14
CODE REFERENCEThis may not be a comprehensive list of procedure codes applicable to this policy.
The code(s) listed below are ONLY medically necessary if the procedure is performed according to the "Policy" section of this document.