21 April 2017
Cheryl Albuquerque, MD, MBA, Valley Children’s Hospital, Madera, CA, USA
Larry Platt, MD, Center for Fetal Medicine and Women’s Ultrasound, Los Angeles, CA, USA
A multitude of tests are available today for prenatal screening. The introduction of cell free DNA screening (cfDNA) for aneuploidy has revolutionized prenatal testing in an era of value-based care. As with any medical test, expectations regarding its performance should be discussed with the patient before the test is ordered. While patients should be offered all relevant testing that is available, patients should have the option to decline any or all testing. It is the provider’s task, however, to make sure that patients understand the benefits and risks of the tests.
cfDNA screening broadens available prenatal testing for women by offering
- An alternative to invasive diagnostic testing for women with screen positive fetuses with high sensitivity and specificity for Trisomy 21 and Trisomy 18 (Trisomy 13 performance is somewhat poorer comparatively).
- Potential reassurance to women for whom invasive diagnostic testing is not an acceptable option.
- Elimination of procedure-related risks, making women less likely to decline further assessment after a high risk result from another form of screening.
With the increasing use of cfDNA screening, the question has arisen about the value of first trimester ultrasound evaluation in patients who have chosen cfDNA screening instead of traditional aneuploidy screening. In addition to screening for aneuploidy, first trimester ultrasound is utilized to estimate gestational age, to confirm cardiac activity, diagnose or evaluate multiple gestations, evaluate a suspected ectopic pregnancy, evaluate vaginal bleeding, evaluate maternal pelvic or adnexal masses or uterine abnormalities, to evaluate suspected hydatidiform mole, and to evaluate causes of pelvic pain.
The first trimester ultrasound examination can assess for certain fetal anomalies such as anencephaly, cystic hygroma, and other structural anomalies. A recent systematic review estimated that approximately half of all structural abnormalities are detectable in first trimester, affording women earlier detection and an early opportunity for diagnostic testing (Karim et al 2016. http://onlinelibrary.wiley.com/doi/10.1002/uog.17246/full
). In this review, it was noted that detection rates were significantly improved by the use of a structured anatomical protocol.
Due to the constantly evolving nature of prenatal screening and the role of ultrasound, the Society for Maternal Fetal Medicine has recently issued a statement on “The role of ultrasound in women who undergo cell –free DNA screening."
Read more on AJOG.org →