Document Detail

Multicenter study of first-trimester screening for trisomy 21 in 75 821 pregnancies: results and estimation of the potential impact of individual risk-orientated two-stage first-trimester screening.
MedLine Citation:
PMID:  15736186     Owner:  NLM     Status:  MEDLINE    
OBJECTIVES: To evaluate the performance of first-trimester screening for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) and maternal serum free beta-human chorionic gonadotropin (beta-hCG) and pregnancy-associated plasma protein-A (PAPP-A). In addition, the potential impact of a new individual risk-orientated two-stage approach to first-trimester screening was examined. METHODS: First-trimester combined screening for trisomy 21 was carried out in 75 821 singleton pregnancies with live fetuses at 11 + 0 to 13 + 6 gestational weeks. The detection and false-positive rates for different risk cut-offs were calculated. To examine the potential impact of an individual risk-orientated two-stage approach to first-trimester screening it was assumed that, after first-trimester combined screening, chorionic villus sampling (CVS) would be performed in all patients with a risk estimate of 1 in 100 or more and in none of those with a risk estimate of less than 1 in 1000. Those in the intermediate-risk category, with a risk estimate of between 1 in 101 and 1 in 1000, would have further assessment of risk by first-trimester ultrasound examination to determine presence/absence of the nasal bone, presence/absence of tricuspid regurgitation or normal/abnormal Doppler velocity waveform in the ductus venosus, and CVS would be performed if their adjusted risk became 1 in 100 or more. RESULTS: Fetal NT and maternal serum free beta-hCG and PAPP-A were successfully measured in all cases. The median maternal age was 31 (range, 13-49) years, the median gestation at screening was 12 (range, 11 + 0 to 13 + 6) weeks and the median fetal crown-rump length was 62 (range, 45-84) mm. Chromosomal abnormalities were identified in 544 pregnancies, including 325 cases of trisomy 21. The estimated risk for trisomy 21 was 1 in 300 or greater in 5.2% of normal pregnancies, in 92.6% of those with trisomy 21, in 88.5% of those with trisomy 18 or 13 and in 85.6% of those with other chromosomal defects. The detection rates for trisomy 21 were about 75% and 80% for respective false-positive rates of 1% and 2%. In the proposed individual risk-orientated two-stage screening for a risk cut-off of 1 in 100 the total false-positive rate would vary with the method used for the second stage of screening from 2.1% for absence of the nasal bone to 2.7% for increased impedance in the ductus venosus and 2.7% for tricuspid regurgitation and the respective detection rates would be 92.0%, 94.2% and 91.7%. CONCLUSIONS: First-trimester combined screening for trisomy 21 is associated with a detection rate of about 90% for a false-positive rate of 5%. Individual risk-orientated two-stage screening for trisomy 21 can potentially identify, in the first trimester of pregnancy, more than 90% of affected fetuses for a false-positive rate of 2-3%.
K H Nicolaides; K Spencer; K Avgidou; S Faiola; O Falcon
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Publication Detail:
Type:  Evaluation Studies; Journal Article; Multicenter Study; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology     Volume:  25     ISSN:  0960-7692     ISO Abbreviation:  Ultrasound Obstet Gynecol     Publication Date:  2005 Mar 
Date Detail:
Created Date:  2005-03-03     Completed Date:  2005-06-16     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9108340     Medline TA:  Ultrasound Obstet Gynecol     Country:  England    
Other Details:
Languages:  eng     Pagination:  221-6     Citation Subset:  IM    
Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, London, UK.
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MeSH Terms
Chorionic Gonadotropin, beta Subunit, Human / blood
Down Syndrome / diagnosis*
Predictive Value of Tests
Pregnancy Trimester, First
Pregnancy-Associated Plasma Protein-A / analysis
Prenatal Diagnosis / methods
Risk Assessment
Ultrasonography, Prenatal*
Reg. No./Substance:
0/Chorionic Gonadotropin, beta Subunit, Human; EC 3.4.24.-/Pregnancy-Associated Plasma Protein-A

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