Standardization of Nuchal Translucency Assessments: Cutoffs, Recommendations and Counseling Approaches
Capstone Project Committee: Martha Decker, MD, MFM, Sat Gupta, PhD (Statistical Consultant), Scott Richter, PhD (Statistical Consultant), Christy Stanley, MS, CGC, Randi Stewart, MS, CGC
Background: The National Society of Genetic Counselors (NSGC) does not have established guidelines regarding counseling for abnormal nuchal translucency (NT) measurements. The American College of Obstetrics and Gynecology recommends using a NT cutoff of 3.5 mm. In the literature, there is a lack of consensus regarding the NT cutoff that should be used to confer a high risk for fetal aneuploidy, which may lead to variability regarding interpretation, counseling and follow up care. Purpose: The goal of this study was to assess the NT cutoffs, recommendations for follow up testing and counseling approaches utilized in assessments performed by prenatal genetic counselors and providers within their clinics. Methods: Prenatal counselors with NSGC membership were surveyed utilizing the NSGC email listserv. Survey data was analyzed for frequency and comparative statistical methods were used. Thematic analysis was performed on qualitative data. Results: 115 participants completed the survey. NT cutoffs used in respondents’ clinics were variable; 3.5 mm (48.7%), 3.0 mm (20%) and ≥ 95% (20%) were most commonly reported. 41.7% of respondents were unaware of what resource(s) their clinic uses to justify their NT cutoff(s). Follow up options of Amniocentesis, Fetal echocardiogram, Target ultrasound, and CVS were the most common follow up options offered although the NT cutoff at which they are offered varied. Drawings/illustrations were used by 62 participants (53.9%) when counseling patients and 56.5% felt that adequate counseling aids are available. 83.5% of respondents thought standardized guidelines would be beneficial and improve patient care. Conclusion: This data did not produce statistical significance to correlate cutoff(s) and follow up testing. However, the variance of the data demonstrates a wide range of interpretation of an abnormal NT. This variability may present challenges in counseling and patient comprehension and may impact patient care. Data from this study may be used to promote further studies and direct the development of specific guidelines.
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