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Aneuploidy Screening: Newer Noninvasive Test Gains Traction

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References


CHALLENGES TO IMPLEMENTATION
cfDNA testing is validated only for singleton pregnancies. Clinicians should obtain a baseline fetal ultrasound to confirm the number of fetuses, gestational age, and viability before ordering cfDNA to ensure it is the most appropriate screening test. This may add to the overall number of early pregnancy ultrasounds conducted.

Counseling patients about aneuploidy screening options is time-consuming and requires discussion of the limitations of each screening method and caution that a negative cfDNA result does not guarantee an unaffected fetus, nor does a positive result guarantee an affected fetus. However, aneuploidy screening is well within the scope of care for family practice clinicians who provide prenatal care, and referral to genetic specialists is not necessary or recommended.

Some patients may request cfDNA in order to facilitate earlier identification of fetal sex. In such cases, clinicians should advise patients that cfDNA testing also assesses trisomy risk. Patients who do not wish to assess their risk for aneuploidy should not receive cfDNA testing.

Finally, while cfDNA is routinely recommended for women with pregnancies considered at high risk for aneuploidy, many insurance companies do not cover the cost of cfDNA for women with low-risk pregnancies, and the test may cost up to $1,700.12 The overall cost-effectiveness of cfDNA for aneuploidy screening in low-risk women is unknown.

References
1. Bianchi DW, Parker RL, Wentworth J, et al; CARE Study Group. DNA sequencing versus standard prenatal aneuploidy screening. N Engl J Med. 2014;370:799-808.
2. Norton ME, Jacobsson B, Swamy GK, et al. Cell-free DNA analysis for noninvasive examination of trisomy. N Engl J Med. 2015;372: 1589-1597.
3. Chiu RW, Akolekar R, Zheng YW, et al. Non-invasive prenatal assessment of trisomy 21 by multiplexed maternal plasma DNA sequencing: large scale validity study. BMJ. 2011; 342:c7401.
4. Ehrich M, Deciu C, Zwiefelhofer T, et al. Noninvasive detection of fetal trisomy 21 by sequencing of DNA in maternal blood: a study in a clinical setting. Am J Obstet Gynecol. 2011;204:205.e1-11.
5. Bianchi DW, Platt LD, Goldberg JD, et al; MatERNal BLood IS Source to Accurately diagnose fetal aneuploidy (MELISSA) Study Group. Genome-wide fetal aneuploidy detection by maternal plasma DNA sequencing. Obstet Gynecol. 2012;119:890-901.
6. Norton ME, Brar H, Weiss J, et al. Non-invasive chromosomal evaluation (NICE) study: results of a multicenter prospective cohort study for detection of fetal trisomy 21 and trisomy 18. Am J Obstet Gynecol. 2012;207: 137.e1-e8.
7. American College of Obstetricians and Gynecologists Committee on Genetics. Committee Opinion No. 545: Noninvasive prenatal testing for fetal aneuploidy. Obstet Gynecol. 2012;120:1532-1534.
8. American College of Obstetricians and Gynecologists Committee on Genetics. Committee Opinion No. 640: Cell-free DNA screening for fetal aneuploidy. Obstet Gynecol. 2015;126:e31-e37.
9. Wang Y, Zhu J, Chen Y, et al. Two cases of placental T21 mosaicism: challenging the detection limits of non-invasive prenatal testing. Prenat Diagn. 2013;33:1207-1210.
10. Choi H, Lau TK, Jiang FM, et al. Fetal aneuploidy screening by maternal plasma DNA sequencing: ‘false positive’ due to confined placental mosaicism. Prenat Diagn. 2013; 33:198-200.
11. Norton ME, Jelliffe-Pawlowski LL, Currier RJ. Chromosome abnormalities detected by current prenatal screening and noninvasive prenatal testing. Obstet Gynecol. 2014;124:979-986.
12. Agarwal A, Sayres LC, Cho MK, et al. Commercial landscape of noninvasive prenatal testing in the United States. Prenat Diagn. 2013;33:521-531.

ACKNOWLEDGEMENT
The PURLs Surveillance System was supported in part by Grant Number UL1RR024999 from the National Center For Research Resources, a Clinical Translational Science Award to the University of Chicago. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Center For Research Resources or the National Institutes of Health.

Copyright © 2016. The Family Physicians Inquiries Network. All rights reserved.

Reprinted with permission from the Family Physicians Inquiries Network and The Journal of Family Practice. 2016;65(1):49-52.

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