NIPT: A Clinical Update
Lee P. Shulman, MD, FACMG, FACOG
The Anna Ross Lapham Professor in Obstetrics and Gynecology
Division of Clinical Genetics, Department of Obstetrics and Gynecology
Feinberg School of Medicine of Northwestern University
Evaluating pregnancies for fetal abnormalities has beena mainstay of prenatal care since the 1960s. From the introduction of amniocentesis for the detection of fetal chromosomal abnormalities to the initial screenings for Tay-Sachs disease and sickle cell disease among individuals of Eastern European Jewish (Ashkenazi) and African ancestries, respectively, the advancement of prenatal screening modalities has sought to develop highly effective screening protocols to identify women and couples who are at an increased risk for detectable fetal abnormalities. With the growing selection of screening tests that evaluate pregnancies for Down syndrome (trisomy 21) and other fetal chromosomal and genomic abnormalities, the development of more effective screening protocols has been a long sought-after goal—one that was achieved with the development of noninvasive prenatal testing (NIPT).
Screening Versus Diagnosis
Despite the frequent interchange of the 2 words by patients and clinicians alike, understanding the difference between screening and diagnosis is critical to empowering women and couples to make truly informed prenatal care decisions that are right for them and for the prenatal information that they wish to acquire. Screening is a riskadjustment process through which clinicians can determine whether to offer diagnostic testing to patients. Residual risk always exists regardless of the actual screening outcome; that is, in no instance is there a guarantee that no fetal chromosomal abnormality exists or is completely ruled out. Diagnosis, on the other hand, relates to a process that determines the presence or absence of a disease state. Screening results should be communicated as either a “positive” or “negative,” whereas diagnostic results are communicated as “normal” or “abnormal.” Examples of screening tests in use in reproductive medicine include second trimester quad-analyte screening and nuchal translucency measurements; examples of diagnostic tests include chorionic villus sampling (CVS) and amniocentesis.
The distinction between screening and diagnostic testing modalities is a critical aspect of the process by which patients decide what testing, if any, they wish to undergo to evaluate their pregnancies. The choice of a screening test provides an adjusted risk for the more common fetal chromosomal abnormalities. Negative results indicate a markedly reduced, but not eliminated, chance for a common fetal chromosomal abnormality, whereas a positive result is indicative of a considerably increased risk for that specific fetal chromosomal abnormality. However, that positive result is not a guarantee that the fetus is so affected, even if other signs are present (eg, an abnormal ultrasound examination) that are associated with fetal abnormality. Accordingly, positive results alone should never be used for pregnancy management decisions; diagnostic testing is strongly supported in all such situations.
To receive CME credit, please read the articles and go to www.omniaeducation.com/NIPT to access the post-test and evaluation.
This supplement is designed to provide ObGyn clinicians with current information on the cell-free DNA screening test options available for fetal chromosomal abnormalities. These screening tests are commonly referred to as Noninvasive Prenatal Screening (NIPS). In August 2020, the American College of Obstetricians and Gynecologists (ACOG) issued a Practice Bulletin entitled “Screening for Fetal Chromosomal Abnormalities” (PB #226). This Practice Bulletin included expanded information regarding the use of NIPS in all patients regardless of maternal age or baseline risk. It also identified NIPS as the most sensitive and specific test for screening for the most common aneuploidies. The authors of this supplement provide additional information on the technology, performance, and clinical utilization of NIPS testing.
Ann Early has nothing to disclose.
Genevieve L. Fairbrother MD, MPH, FACOG has nothing to disclose.
Morry Fiddler, PhD receives a salary from Insight Medical Genetics.
Barry A. Fiedel, PhD has nothing to disclose.
Amanda Hilferty has nothing to disclose.
Robert Schneider, MSW has nothing to disclose.
Lee P. Shulman, MD, FACMG, FACOG receives consulting fees from Biogix, Celula, Cooper Surgical, Natera, and Vermillion/Aspira and is a speaker for Bayer, Lupin Pharmaceuticals, Inc., and Myriad.
Andrew F. Wagner, MD, FACMG, FACOG has nothing to disclose.
Haichuan Zhang, PhD has ownership interest in Celula China Medical Technology Co.
After participating in this educational activity, participants should be better able to:
- Overcome barriers and demonstrate competency in integrating ACOG/Society for Maternal-Fetal Medicine Noninvasive Prenatal Testing Committee Opinions/Practice Bulletins recommendations into clinical decisionmaking surrounding prenatal visits for all pregnant patients.
- Explain the benefits and disadvantages of traditional fetal chromosomal aneuploidy screening tests compared with noninvasive screening tests.
- Define the technology that is the basis of the various noninvasive screening tests, including the role that fetal fraction plays in influencing results.
- Explain the expanding role of NIPS in the general obstetrical population.
ACCREDITATION AND CREDIT DESIGNATION STATEMENTS:
Global Learning Collaborative (GLC) is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.
Global Learning Collaborative designates this enduring material for a maximum of 1 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.
This activity is designed to meet the educational needs of the obstetrician and gynecologist, family physician, internal medicine physician, physician assistant, nurse practitioner, and certified nurse midwife.
This activity is supported by an independent educational grant from Roche Diagnostics.
The views and opinions expressed in this educational activity are those of the faculty and do not necessarily represent the views of GLC and Omnia Education. This presentation is not intended to define an exclusive course of patient management; the participant should use his/her clinical judgment, knowledge, experience, and diagnostic skills in applying or adopting for professional use any of the information provided herein. Any procedures, medications, or other courses of diagnosis or treatment discussed or suggested in this activity should not be used by clinicians without evaluation of their patients’ conditions and possible contraindications or dangers in use, review of any applicable manufacturer’s product information, and comparison with recommendations of other authorities. Links to other sites may be provided as additional sources of information. Once you elect to link to a site outside of Omnia Education you are subject to the terms and conditions of use, including copyright and licensing restriction, of that site.
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