{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,5]],"date-time":"2026-10-05T09:38:58Z","timestamp":1791193138142,"version":"4.1.0"},"reference-count":23,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2005,2,25]],"date-time":"2005-02-25T00:00:00Z","timestamp":1109289600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Ultrasound in Obstet &amp; Gyne"],"published-print":{"date-parts":[[2005,3]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Objectives<\/jats:title><jats:p>To evaluate the performance of first\u2010trimester screening for trisomy 21 by a combination of maternal age, fetal nuchal translucency (NT) and maternal serum free \u03b2\u2010human chorionic gonadotropin (\u03b2\u2010hCG) and pregnancy\u2010associated plasma protein\u2010A (PAPP\u2010A). In addition, the potential impact of a new individual risk\u2010orientated two\u2010stage approach to first\u2010trimester screening was examined.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>First\u2010trimester 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\u2010positive rates for different risk cut\u2010offs were calculated. To examine the potential impact of an individual risk\u2010orientated two\u2010stage approach to first\u2010trimester screening it was assumed that, after first\u2010trimester 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\u2010risk category, with a risk estimate of between 1 in 101 and 1 in 1000, would have further assessment of risk by first\u2010trimester 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.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Fetal NT and maternal serum free \u03b2\u2010hCG and PAPP\u2010A were successfully measured in all cases. The median maternal age was 31 (range, 13\u201349) years, the median gestation at screening was 12 (range, 11 + 0 to 13 + 6) weeks and the median fetal crown\u2013rump length was 62 (range, 45\u201384) 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\u2010positive rates of 1% and 2%. In the proposed individual risk\u2010orientated two\u2010stage screening for a risk cut\u2010off of 1 in 100 the total false\u2010positive 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%.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>First\u2010trimester combined screening for trisomy 21 is associated with a detection rate of about 90% for a false\u2010positive rate of 5%. Individual risk\u2010orientated two\u2010stage screening for trisomy 21 can potentially identify, in the first trimester of pregnancy, more than 90% of affected fetuses for a false\u2010positive rate of 2\u20133%. Copyright \u00a9 2005 ISUOG. Published by John Wiley &amp; Sons, Ltd.<\/jats:p><\/jats:sec>","DOI":"10.1002\/uog.1860","type":"journal-article","created":{"date-parts":[[2005,2,25]],"date-time":"2005-02-25T20:46:04Z","timestamp":1109364364000},"page":"221-226","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":359,"title":["Multicenter study of first\u2010trimester screening for trisomy 21 in 75 821 pregnancies: results and estimation of the potential impact of individual risk\u2010orientated two\u2010stage first\u2010trimester screening"],"prefix":"10.1002","volume":"25","author":[{"given":"K. H.","family":"Nicolaides","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"K.","family":"Spencer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"K.","family":"Avgidou","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"S.","family":"Faiola","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"O.","family":"Falcon","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2005,2,25]]},"reference":[{"key":"e_1_2_6_2_2","doi-asserted-by":"publisher","DOI":"10.1046\/j.1469-0705.1999.13040231.x"},{"key":"e_1_2_6_3_2","doi-asserted-by":"publisher","DOI":"10.1046\/j.1469-0705.2002.00808.x"},{"key":"e_1_2_6_4_2","doi-asserted-by":"publisher","DOI":"10.1046\/j.1471-0528.2003.02246.x"},{"key":"e_1_2_6_5_2","first-page":"1","article-title":"Antenatal screening for Down's syndrome","volume":"2","author":"Wald NJ","year":"1998","journal-title":"Health Technol Assess"},{"key":"e_1_2_6_6_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(01)06709-5"},{"key":"e_1_2_6_7_2","doi-asserted-by":"publisher","DOI":"10.1046\/j.1469-0705.1998.12060380.x"},{"key":"e_1_2_6_8_2","doi-asserted-by":"publisher","DOI":"10.1136\/heart.89.9.1071"},{"key":"e_1_2_6_9_2","doi-asserted-by":"publisher","DOI":"10.1046\/j.1469-0705.1999.13030167.x"},{"key":"e_1_2_6_10_2","doi-asserted-by":"publisher","DOI":"10.1002\/pd.431"},{"key":"e_1_2_6_11_2","doi-asserted-by":"publisher","DOI":"10.1002\/pd.628"},{"key":"e_1_2_6_12_2","doi-asserted-by":"publisher","DOI":"10.1002\/uog.167"},{"key":"e_1_2_6_13_2","doi-asserted-by":"publisher","DOI":"10.1002\/pd.694"},{"key":"e_1_2_6_14_2","doi-asserted-by":"publisher","DOI":"10.1002\/uog.184"},{"key":"e_1_2_6_15_2","doi-asserted-by":"publisher","DOI":"10.1159\/000072994"},{"key":"e_1_2_6_16_2","doi-asserted-by":"publisher","DOI":"10.1002\/uog.170"},{"key":"e_1_2_6_17_2","doi-asserted-by":"publisher","DOI":"10.1002\/uog.992"},{"key":"e_1_2_6_18_2","doi-asserted-by":"publisher","DOI":"10.1046\/j.1469-0705.2001.00395.x"},{"key":"e_1_2_6_19_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1471-0528.2002.01482.x"},{"key":"e_1_2_6_20_2","doi-asserted-by":"publisher","DOI":"10.1159\/000063185"},{"key":"e_1_2_6_21_2","doi-asserted-by":"publisher","DOI":"10.1159\/000048007"},{"key":"e_1_2_6_22_2","doi-asserted-by":"publisher","DOI":"10.1002\/pd.716"},{"key":"e_1_2_6_23_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(86)91218-3"},{"key":"e_1_2_6_24_2","doi-asserted-by":"publisher","DOI":"10.1016\/0140-6736(92)92946-D"}],"container-title":["Ultrasound in Obstetrics &amp; Gynecology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1002%2Fuog.1860","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1002%2Fuog.1860","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/obgyn.onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/uog.1860","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,9,28]],"date-time":"2023-09-28T21:03:29Z","timestamp":1695935009000},"score":1,"resource":{"primary":{"URL":"https:\/\/obgyn.onlinelibrary.wiley.com\/doi\/10.1002\/uog.1860"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2005,2,25]]},"references-count":23,"journal-issue":{"issue":"3","published-print":{"date-parts":[[2005,3]]}},"alternative-id":["10.1002\/uog.1860"],"URL":"https:\/\/doi.org\/10.1002\/uog.1860","archive":["Portico"],"relation":{},"ISSN":["0960-7692","1469-0705"],"issn-type":[{"value":"0960-7692","type":"print"},{"value":"1469-0705","type":"electronic"}],"subject":[],"published":{"date-parts":[[2005,2,25]]},"assertion":[{"value":"2005-01-20","order":1,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2005-02-25","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}