Nuchal Translucency with or without Maternal Serum PAPP-A and Free ß-hCG Levels as a First-Trimester Screening for Down Syndrome (Trisomy 21) and Edward Syndrome (Trisomy 18)
DESCRIPTION
Nuchal translucency refers to the thickness of the space between the back of the fetal neck and the overlying skin. Nuchal translucency by ultrasound examination should be performed with the fetus in the sagittal view for a crown-rump measurement. Care should be taken to distinguish nuchal skin from the amnionic membrane. Nuchal translucency is performed during the latter part of the first-trimester (10-13 weeks) of gestation. Appropriately trained sonographers who comply with monitored measurement standardizations should perform the ultrasound.
Nuchal translucency is typically performed in conjunction with maternal serum biochemical tests. The biochemical tests are pregnancy-associated plasma protein-A (PAPP-A) levels and free beta-human chorionic gonadotropin (ß-hCG). Laboratories that can demonstrate good quality assurance performance should perform the biochemical tests.
First-trimester nuchal translucency combined with maternal serum PAPP-A and free ß-hCG levels is being utilized as a screening for increased prenatal risk of chromosomal defects (e.g., trisomy 21 - Down syndrome, trisomy 18 - Edward syndrome). If a screening test result is abnormal, the pregnant individual should have access to an appropriate diagnostic test and resources available to provide comprehensive counseling.
POLICY
First-trimester nuchal translucency combined with maternal serum PAPP-A and free ß-hCG levels as a screening for women who are adequately counseled and desire information on the risk of having a child with Down syndrome and Edward syndrome is considered medically necessary.
First-trimester nuchal translucency used alone as a screening for chromosomal defects, including, but not limited to, the following: Down syndrome and Edward syndrome is considered investigational.
ADDITIONAL INFORMATION
Nuchal translucency measurement used alone as a screening for chromosomal defects without serum screening (e.g., maternal serum PAPP-A and free ß-hCG levels) has a low specificity. Therefore, nuchal translucency measurement used alone is not as good as other available screening methods for detection of chromosomal defects.
SOURCES
ACOG Committee on Practice Bulletins. (2007). ACOG Practice Bulletin. Clinical management guidelines for obstetrician-gynecologists. Number 77. Screening for fetal chromosomal abnormalities. Obstetrics and Gynecology, 109 (1), 217-227.
Agency for Healthcare Research & Quality. Part G. Congenital disorders. Screening for Down syndrome. Retrieved May 16, 2008 from http://www.ahrq.gov/clinic/2ndcps/downsyn.pdf.
Bernstein, P. S. (2004). Highlights from The Society of Maternal-Fetal Medicine 24th annual clinical meeting. Medscape Ob/Gyn & Women's Health, 9 (1). (Level 1 Evidence - Independent study)
BlueCross BlueShield Association. Medical Policy Reference Manual. (4:2008). First-trimester detection of Down syndrome using fetal ultrasound assessment of nuchal translucency combined with maternal serum assessment (4.01.14). Retrieved May 16, 2008 from BlueWeb. (20 articles and/or guidelines reviewed)
Bush, M. C., & Malone, F. D. (2005). Down syndrome screening in twins. Clinics in Perinatology, 32 (2), 373-386.
Chasen, S. T. & Skupski, D. W. (2003). Ethical dimensions of nuchal translucency screening. Clinics in Perinatology, 30 (1), 95-102.
Donnenfeld, A. E., Cutillo, D., Horwitz, J., & Knops, J. (2006). Prospective study of 22q11 deletion analysis in fetuses with excess nuchal translucency. American Journal of Obstetrics and Gynecology, 194 (2), 508-511. (Level 4 Evidence - Independent study)
Evans, M., Van Decruves, H., & Nicolaides, K. H. (2007). Nuchal translucency measurements for first-trimester screening: The ‘price’ of inaccuracy’ Fetal Diagnosis and Therapy, 22, 401-404. (Level 3 Evidence - Independent study)
Fries, N., Althuser, M., Fontanges, M., Talmant, C., Jouk, P. S., Tindel, M., et al. (2007). Quality control of an image-scoring method for nuchal translucency ultrasonography. American Journal of Obstetrics and Gynecology, 196 (3), 272-e1-5. (Level 4 Evidence - Independent study)
Hayes. Medical Technology Directory. (2005, December). First-trimester prenatal screening using nuchal translucency combined with maternal PAPP-A and free β-hCG levels. Retrieved May 16, 2008 from www.Hayesinc.com/subscribers. (49 articles and/or guidelines reviewed)
Matias, A., Montenegro, N., & Blickstein, I. (2005). Down syndrome screening in multiple pregnancies. Obstetrics and Gynecology Clinics of North America, 32 (1), 81-96.
Nyberg, D. A., Hyett, J., Johnson, J., & Souter, V. (2006). First-trimester screening. Radiologic Clinics of North America, 44 (6), 837-861.
Senet, M. V., Bussieres, L., Couderc, S., Roume, J., Rozenberg, P., Bouyer, J., & Ville, Y. (2007). Long-term outcome of children born after a first-trimester measurement of nuchal translucency at the 99th percentile or greater with normal karyotype: A prospective study. American Journal of Obstetrics and Gynecology, 196 (1), 531-536. (Level 2 Evidence - Independent study)
The Fetal Medicine Foundation. Downs screening at 11-14 weeks. Retrieved April 25, 2003 from http://www.fetalmedicine.com/f-downs.htm.
Wald NJ, Rodeck C, Hackshaw AK, Walters J, Chitty L, Macinson AM. First and second trimester antenatal screening for Down's syndrome: the results of the Serum, Urine and Ultrasound Screening Study (SURUSS). Health Technol Assess 2003;7(11).
Wapner, R., Thom, E., Simpson, J. L., Pergament, E., Silver, R., Filkins, K., et al. (2003). First-trimester screening for trisomies 21 and 18. The New England Journal of Medicine, 349 (15), 1405-1413. (Level 1 Evidence - Industry sponsored)
Weiner, Z., Goldstein, I., Bombard, A., Applewhite, L. & Itzkivits-Eldor, J. (2007). Screening for structural fetal anomalies during the nuchal translucency ultrasound examination. American Journal of Obstetrics and Gynecology, 197 (2), 181-e1-5. (Level 3 Evidence - Independent study)
ORIGINAL EFFECTIVE DATE: 11/1/2003
MOST RECENT REVIEW DATE: 6/12/2008