Use of Genetic Testing after Abnormal Screening Ultrasound: A Descriptive Cohort Study.

Background/aims: The study aimed to characterize the use of genetic testing after abnormal screening ultrasound.

Methods: We performed a retrospective review of patients undergoing genetic testing after abnormal ultrasound. Genetic evaluation consisted of noninvasive prenatal screening (NIPS) or amniocentesis. Classification of ultrasound findings, type of genetic testing, and results were collected.

Results: A total of 139 subjects underwent genetic evaluation after abnormal screening ultrasound. Screening via NIPS was pursued by 61 (44%) patients while 78 (56%) proceeded directly to amniocentesis. Patients electing for amniocentesis had more cardiac, neurologic, and gastrointestinal malformations while soft markers for aneuploidy prompted more NIPS screening. Results were negative in 85% of the NIPS group compared to 60% of the amniocentesis group. Only 8% of patients who underwent NIPS proceeded to diagnostic testing.

Conclusion: Patients pursuing NIPS after abnormal ultrasound had more soft markers of aneuploidy. Patients pursuing diagnostic testing were more likely to have major structural malformations and more total abnormalities identified. Patients who proceeded directly to amniocentesis were more likely to have abnormal genetic testing.