Objective: This study was undertaken to evaluate the performance of a 1- stop clinic for first- trimester assessment of risk (OSCAR)for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) thick...Objective: This study was undertaken to evaluate the performance of a 1- stop clinic for first- trimester assessment of risk (OSCAR)for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) thickness, and maternal serum- free β - human chorionic gonadotrophin (hCG) and pregnancy- associated plasma protein- A (PAPP- A). Study design: OSCAR was carried out in 30,564 pregnancies at 11 to 13+ 6 weeks. Patient- specific risks for trisomy 21 and detection and falsepositive rates were calculated. Results: The median maternal age was 34 (range 15- 49) years. Chromosomal abnormalities were identified in 330 pregnancies, including 196 cases of trisomy 21. The estimated risk for trisomy 21 was 1 in 300 or greater in 7.5% of the normal pregnancies, in 93.4% of those with trisomy 21 and in 88.8% of those with other chromosomal defects. Conclusion: The most effective method of screening for chromosomal defects is by first- trimester fetal NT and maternal serum biochemistry.展开更多
Objective: To investigate an approach for the analysis of samples obtained in screening for trisomy 21 that retains the advantages of quantitative fluorescent polymerase chain reaction (qf- PCR) over full karyotyping ...Objective: To investigate an approach for the analysis of samples obtained in screening for trisomy 21 that retains the advantages of quantitative fluorescent polymerase chain reaction (qf- PCR) over full karyotyping and maximises the detection of clinically significant abnormalities. Design: Observational study. Setting: Tertiary referral centre. Subjects: 17 446 pregnancies, from which chorionic villous samples had been taken after assessment of risk for trisomy 21 by measurement of fetal nuchal translucency (NT) thickness at 11 to 13th weeks of gestation. Interventions: Analysis of chorionic villous samples by full karyotyping and by qf- PCR for chromosomes 13, 18, 21, X, and Y. Main outcome measure: Detection of clinically significant chromosomal abnormalities. Results: The fetal karyotype was normal in 15 548 (89.1% ) cases and abnormal in 1898 (10.9% ) cases, including 1722 with a likely clinically significant adverse outcome. Karyotyping all cases would lead to the diagnosis of all clinically significant abnormalities, and a policy of relying entirely on qf- PCR would lead to the diagnosis of 97.9% of abnormalities. An alternative strategy where by qf- PCR is the main method of analysis and full karyotyping is reserved for those cases with a minimum fetal NT thickness of 4 mm would require full karyotyping in 10.1% of the cases, would identify 99.0% of the significant abnormalities, and would cost 60% less than full karyotyping for all. Conclusions: In the diagnosis of chromosomal abnormalities after first trimester screening for trisomy 21, a policy of qf- PCR for all samples and karyotyping only if the fetal NT thickness is increased would reduce the economic costs, provide rapid delivery of results, and identify 99% of the clinically significant chromosomal abnormalities.展开更多
文摘Objective: This study was undertaken to evaluate the performance of a 1- stop clinic for first- trimester assessment of risk (OSCAR)for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) thickness, and maternal serum- free β - human chorionic gonadotrophin (hCG) and pregnancy- associated plasma protein- A (PAPP- A). Study design: OSCAR was carried out in 30,564 pregnancies at 11 to 13+ 6 weeks. Patient- specific risks for trisomy 21 and detection and falsepositive rates were calculated. Results: The median maternal age was 34 (range 15- 49) years. Chromosomal abnormalities were identified in 330 pregnancies, including 196 cases of trisomy 21. The estimated risk for trisomy 21 was 1 in 300 or greater in 7.5% of the normal pregnancies, in 93.4% of those with trisomy 21 and in 88.8% of those with other chromosomal defects. Conclusion: The most effective method of screening for chromosomal defects is by first- trimester fetal NT and maternal serum biochemistry.
文摘Objective: To investigate an approach for the analysis of samples obtained in screening for trisomy 21 that retains the advantages of quantitative fluorescent polymerase chain reaction (qf- PCR) over full karyotyping and maximises the detection of clinically significant abnormalities. Design: Observational study. Setting: Tertiary referral centre. Subjects: 17 446 pregnancies, from which chorionic villous samples had been taken after assessment of risk for trisomy 21 by measurement of fetal nuchal translucency (NT) thickness at 11 to 13th weeks of gestation. Interventions: Analysis of chorionic villous samples by full karyotyping and by qf- PCR for chromosomes 13, 18, 21, X, and Y. Main outcome measure: Detection of clinically significant chromosomal abnormalities. Results: The fetal karyotype was normal in 15 548 (89.1% ) cases and abnormal in 1898 (10.9% ) cases, including 1722 with a likely clinically significant adverse outcome. Karyotyping all cases would lead to the diagnosis of all clinically significant abnormalities, and a policy of relying entirely on qf- PCR would lead to the diagnosis of 97.9% of abnormalities. An alternative strategy where by qf- PCR is the main method of analysis and full karyotyping is reserved for those cases with a minimum fetal NT thickness of 4 mm would require full karyotyping in 10.1% of the cases, would identify 99.0% of the significant abnormalities, and would cost 60% less than full karyotyping for all. Conclusions: In the diagnosis of chromosomal abnormalities after first trimester screening for trisomy 21, a policy of qf- PCR for all samples and karyotyping only if the fetal NT thickness is increased would reduce the economic costs, provide rapid delivery of results, and identify 99% of the clinically significant chromosomal abnormalities.
