Stefan C Kane1,2,3, Karen L Reidy1,3, Fiona Norris4, Deborah L Nisbet3,5,6, Louise H Kornman2,3,5, Ricardo Palma-Dias1,2,3,5. 1. Pregnancy Research Centre, Department of Maternal Fetal Medicine, The Royal Women's Hospital, Parkville, VIC, Australia. 2. The University of Melbourne, Department of Obstetrics and Gynaecology, The Royal Women's Hospital, Parkville, VIC, Australia. 3. Ultrasound Department, Pauline Gandel Women's Imaging Centre, The Royal Women's Hospital, Parkville, VIC, Australia. 4. Victorian Clinical Genetics Services, Parkville, VIC, Australia. 5. Women's Ultrasound Melbourne, Parkville, VIC, Australia. 6. The University of Melbourne, Departments of Medicine and Radiology, Parkville, VIC, Australia.
Abstract
OBJECTIVES: To quantify the impact of cell-free DNA (cfDNA) screening on chorionic villus sampling (CVS) test indications and outcomes in a tertiary maternity service. METHODS: Retrospective cohort study of all CVS procedures performed for any indication on singleton pregnancies at The Royal Women's Hospital, Melbourne, and at Women's Ultrasound Melbourne, Australia, between August 2008 and February 2015. Karyotypes were classified according to pathogenicity and detectability by standard cfDNA screening panels. RESULTS: A total of 2051 CVS procedures, 25 373 twelve-week scans and 2394 cfDNA tests were performed. The CVS rate per 12-week scan fell from 9.8 to 3.9% following introduction of cfDNA screening. The yield of pathogenic chromosomal anomalies per CVS increased from 12.9 to 25.2%, with 70% of pathogenic results now comprising T21, up from 52%. Sixteen (5.3%) of the pathogenic chromosomal abnormalities identified on CVS would not have been predicted by current cfDNA tests. CONCLUSIONS: There is an evolving tension between improved screening performance for common aneuploidies offered by cfDNA testing, and the increasing diagnostic utility of molecular karyotyping. However, the risk of not identifying pathogenic chromosomal abnormalities is low if cfDNA screening is offered in the absence of a structural fetal anomaly, increased nuchal translucency or relevant family history.
OBJECTIVES: To quantify the impact of cell-free DNA (cfDNA) screening on chorionic villus sampling (CVS) test indications and outcomes in a tertiary maternity service. METHODS: Retrospective cohort study of all CVS procedures performed for any indication on singleton pregnancies at The Royal Women's Hospital, Melbourne, and at Women's Ultrasound Melbourne, Australia, between August 2008 and February 2015. Karyotypes were classified according to pathogenicity and detectability by standard cfDNA screening panels. RESULTS: A total of 2051 CVS procedures, 25 373 twelve-week scans and 2394 cfDNA tests were performed. The CVS rate per 12-week scan fell from 9.8 to 3.9% following introduction of cfDNA screening. The yield of pathogenic chromosomal anomalies per CVS increased from 12.9 to 25.2%, with 70% of pathogenic results now comprising T21, up from 52%. Sixteen (5.3%) of the pathogenic chromosomal abnormalities identified on CVS would not have been predicted by current cfDNA tests. CONCLUSIONS: There is an evolving tension between improved screening performance for common aneuploidies offered by cfDNA testing, and the increasing diagnostic utility of molecular karyotyping. However, the risk of not identifying pathogenic chromosomal abnormalities is low if cfDNA screening is offered in the absence of a structural fetal anomaly, increased nuchal translucency or relevant family history.