/*-->*/
Ryan Longman, MDThe field of obstetrics has always aimed to optimize the ability to screen pregnancies for aneuploidy; trisomy 21, trisomy 18, and trisomy 13. A recent study by Saito et al. in The Journal of Obstetric and Gynaecologic Research examined this issue. They did a retrospective analysis to evaluate the utility of adding a first trimester ultrasound screen to women that received positive NIPT results. The first trimester ultrasound included not only an evaluation for ultrasound markers of fetal aneuploidy but also a thorough anatomical assessment of the fetus for structural defects. They found that by adding the first trimester ultrasound, the positive predictive value (PPV) of NIPT for trisomy 18 increased (PPV for trisomy 13 and 21 were already 100% using NIPT alone). Although this finding is academically interesting and may aid in counseling patients with a positive result for trisomy 18 on NIPT, society recommendations are for diagnostic genetic testing with either chorionic villus sampling (CVS) or amniocentesis when abnormal results are found on NIPT, regardless of fetal ultrasound findings.
Prenatal ultrasound detects structural fetal abnormalities in about 3% of pregnancies. When structural fetal abnormalities are found on prenatal ultrasound, diagnostic genetic testing with either CVS or amniocentesis are recommended. Classically, this has meant fetal karyotype and chromosomal microarray testing (CMA). Recently, a new type of genetic testing has become available on fetal samples, whole-exome sequencing (WES). Smogavec et al. assesses this new technology and its ability to detect fetal genetic abnormalities. They retrospectively studied 90 fetuses with abnormalities detected on prenatal ultrasound that had normal CMA results and negative fluorescence in situ hybridization analysis testing for aneuploidy. They found WES testing added a 34.4% increased rate of detection of fetal genetic abnormalities. WES is a powerful tool for genetic diagnosis in fetuses with structural anomalies and should be considered anytime a karyotype or CMA is normal in a fetus with structural anomalies.
Lastly, prenatal genetic diagnosis at an early gestational age is critical for medical management of fetuses with anomalies. In a cohort study, Chen et al. assess the simultaneous combined use of CNV-seq and WES on testing turnaround time. They found by running the testing simultaneously, rather than sequentially, this would decrease testing time from over a month to less than 2 weeks. This strategy of testing could potentially decrease the time from detection of a fetal anomaly on ultrasound to a genetic diagnosis allowing for earlier counseling and medical guidance.
Author and Disclosure Information
Ryan Longman, MD, Associate Professor, Department of Obstetrics and Gynecology, University of Chicago, Pritzker School of Medicine; Director, Ultrasound and Genetics, Fetal Neonatal Care Center, University of Chicago Medical Center, Chicago, IL
Ryan Longman, MD, has disclosed no relevant financial relationships.
Ryan Longman, MD, Associate Professor, Department of Obstetrics and Gynecology, University of Chicago, Pritzker School of Medicine; Director, Ultrasound and Genetics, Fetal Neonatal Care Center, University of Chicago Medical Center, Chicago, IL
Ryan Longman, MD, has disclosed no relevant financial relationships.
Author and Disclosure Information
Ryan Longman, MD, Associate Professor, Department of Obstetrics and Gynecology, University of Chicago, Pritzker School of Medicine; Director, Ultrasound and Genetics, Fetal Neonatal Care Center, University of Chicago Medical Center, Chicago, IL
Ryan Longman, MD, has disclosed no relevant financial relationships.
Dr. Longman scans the journals, so you don’t have to!
Dr. Longman scans the journals, so you don’t have to!
/*-->*/
Ryan Longman, MDThe field of obstetrics has always aimed to optimize the ability to screen pregnancies for aneuploidy; trisomy 21, trisomy 18, and trisomy 13. A recent study by Saito et al. in The Journal of Obstetric and Gynaecologic Research examined this issue. They did a retrospective analysis to evaluate the utility of adding a first trimester ultrasound screen to women that received positive NIPT results. The first trimester ultrasound included not only an evaluation for ultrasound markers of fetal aneuploidy but also a thorough anatomical assessment of the fetus for structural defects. They found that by adding the first trimester ultrasound, the positive predictive value (PPV) of NIPT for trisomy 18 increased (PPV for trisomy 13 and 21 were already 100% using NIPT alone). Although this finding is academically interesting and may aid in counseling patients with a positive result for trisomy 18 on NIPT, society recommendations are for diagnostic genetic testing with either chorionic villus sampling (CVS) or amniocentesis when abnormal results are found on NIPT, regardless of fetal ultrasound findings.
Prenatal ultrasound detects structural fetal abnormalities in about 3% of pregnancies. When structural fetal abnormalities are found on prenatal ultrasound, diagnostic genetic testing with either CVS or amniocentesis are recommended. Classically, this has meant fetal karyotype and chromosomal microarray testing (CMA). Recently, a new type of genetic testing has become available on fetal samples, whole-exome sequencing (WES). Smogavec et al. assesses this new technology and its ability to detect fetal genetic abnormalities. They retrospectively studied 90 fetuses with abnormalities detected on prenatal ultrasound that had normal CMA results and negative fluorescence in situ hybridization analysis testing for aneuploidy. They found WES testing added a 34.4% increased rate of detection of fetal genetic abnormalities. WES is a powerful tool for genetic diagnosis in fetuses with structural anomalies and should be considered anytime a karyotype or CMA is normal in a fetus with structural anomalies.
Lastly, prenatal genetic diagnosis at an early gestational age is critical for medical management of fetuses with anomalies. In a cohort study, Chen et al. assess the simultaneous combined use of CNV-seq and WES on testing turnaround time. They found by running the testing simultaneously, rather than sequentially, this would decrease testing time from over a month to less than 2 weeks. This strategy of testing could potentially decrease the time from detection of a fetal anomaly on ultrasound to a genetic diagnosis allowing for earlier counseling and medical guidance.
/*-->*/
Ryan Longman, MDThe field of obstetrics has always aimed to optimize the ability to screen pregnancies for aneuploidy; trisomy 21, trisomy 18, and trisomy 13. A recent study by Saito et al. in The Journal of Obstetric and Gynaecologic Research examined this issue. They did a retrospective analysis to evaluate the utility of adding a first trimester ultrasound screen to women that received positive NIPT results. The first trimester ultrasound included not only an evaluation for ultrasound markers of fetal aneuploidy but also a thorough anatomical assessment of the fetus for structural defects. They found that by adding the first trimester ultrasound, the positive predictive value (PPV) of NIPT for trisomy 18 increased (PPV for trisomy 13 and 21 were already 100% using NIPT alone). Although this finding is academically interesting and may aid in counseling patients with a positive result for trisomy 18 on NIPT, society recommendations are for diagnostic genetic testing with either chorionic villus sampling (CVS) or amniocentesis when abnormal results are found on NIPT, regardless of fetal ultrasound findings.
Prenatal ultrasound detects structural fetal abnormalities in about 3% of pregnancies. When structural fetal abnormalities are found on prenatal ultrasound, diagnostic genetic testing with either CVS or amniocentesis are recommended. Classically, this has meant fetal karyotype and chromosomal microarray testing (CMA). Recently, a new type of genetic testing has become available on fetal samples, whole-exome sequencing (WES). Smogavec et al. assesses this new technology and its ability to detect fetal genetic abnormalities. They retrospectively studied 90 fetuses with abnormalities detected on prenatal ultrasound that had normal CMA results and negative fluorescence in situ hybridization analysis testing for aneuploidy. They found WES testing added a 34.4% increased rate of detection of fetal genetic abnormalities. WES is a powerful tool for genetic diagnosis in fetuses with structural anomalies and should be considered anytime a karyotype or CMA is normal in a fetus with structural anomalies.
Lastly, prenatal genetic diagnosis at an early gestational age is critical for medical management of fetuses with anomalies. In a cohort study, Chen et al. assess the simultaneous combined use of CNV-seq and WES on testing turnaround time. They found by running the testing simultaneously, rather than sequentially, this would decrease testing time from over a month to less than 2 weeks. This strategy of testing could potentially decrease the time from detection of a fetal anomaly on ultrasound to a genetic diagnosis allowing for earlier counseling and medical guidance.
