Nuchal translucency thickness measurements for fetal aneuploidy screening: Log NT-MoM or Delta-NT, performer-specific medians and ultrasound training (original) (raw)
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Ultrasound in Obstetrics and Gynecology, 2003
Objective To examine the detection rate of chromosomal abnormalities using a combination of nuchal translucency (NT) and maternal age in a United States population. Methods A total of 2131 pregnancies with 2339 fetuses underwent NT screening from April 2000 to April 2002 in our ultrasound unit. Nuchal translucency was measured from 11 to 14 weeks' gestation. Fetal crown-rump length (CRL) was also measured. The risk for trisomy 21 was calculated from a combination of maternal age and fetal NT with the use of software provided by The Fetal Medicine Foundation (FMF). Sensitivity and false-positive rates were calculated for different risk cutoffs. Results Chromosomal defects were diagnosed in 32 cases, including 12 cases of trisomy 21 and 10 cases of trisomy 18. The estimated risk based on maternal age and fetal NT was 1 in 300 or greater in 195 (8.3%) cases and these included 10/12 (83.3%) pregnancies with trisomy 21 and 9/10 (90.0%) pregnancies with trisomy 18. Conclusion A combination of maternal age and fetal NT provides an effective method of screening for chromosomal defects. Using ultrasound techniques and risk algorithms from The FMF, the performance of the test in an American population is similar to that described in international populations.
Ultrasound in Obstetrics and Gynecology, 2009
K E Y W O R D S: first trimester; nuchal translucency; quality assurance; screening; trisomy 21 ABSTRACT Objectives To examine the effect of deviations in median nuchal translucency thickness (NT) and the spread in measurements on the performance of screening for trisomy 21 by maternal age and fetal NT, and by maternal age, fetal NT and maternal serum biochemistry.
Fetal Diagnosis and Therapy, 2008
Objective: First-trimester screening (FTS) has a trisomy 21 detection rate of about 90%. Despite profound training, the practically reached measurement quality of nuchal translucency (NT) is probably not optimal. This study investigated the impact of measurement errors on FTS. Methods: The data on 10,116 combined FTSs were obtained in a multicenter study. Risk assessment was performed by the JOY software following the Nicolaides risk calculation principles. To investigate the impact of measurement errors, the NT values were artificially altered and the adjusted risks were recalculated. Test performance parameters were obtained and compared with the correct measurements. Results: In this study 85 fetuses were genetically affected. The screening was wrongly inconspicuous in 12 cases and in 479 cases the FTS offered false-positive results. An assumed NT error of ±0.1 mm already causes a highly significant change in the false-positive rate. A difference of –0.2 mm leads to a visible cha...
Acta Obstetricia et Gynecologica Scandinavica, 1998
Background. To evaluate the implementation of nuchal translucency measurement as an additional examination within the first trimester routine ultrasound in an unselected population of women. Methods. A prospective study in which all pregnant women during 1994, referred for the first trimester routine ultrasound scan, were asked to participate. Of a total of 1852 women with a viable pregnancy, results from 1444 women were evaluated. When a nuchal translucency of 4 mm or more was found, the woman was offered both a genetic amniocentesis in gestational week 13-15 and an additional ultrasound examination in gestational week 18-19. Results. Six fetuses had a nuchal translucency of 4 mm or more and none of these had any chromosomal abnormality. Neither had any of the fetuses in the study, karyotyped for other reasons, any chromosomal defect and nor was there any child born with aneuploidy in the study population. No strong relation between major malformations e.g. abnormalities of the heart and increased nuchal translucency was found. The fetus with the largest nuchal translucency (Ω6 mm) was born healthy. Conclusion. The efficacy of nuchal translucency measurement needs further evaluation before it can be introduced as a screening method in an unselected pregnant population.
Central Asian Journal of Medical Sciences
Objectives: The aim of study is to determine the sensitivity and specificity of screening for fetal trisomy 21 in the first trimester of pregnancy using a combination of maternal serum biomarkers and ultrasonography. The objectives of this study were to first duplicate and confirm within the Mongolian population, the results of other similar studies. Our results corroborated closely with those of other studies and further allowed us to draw conclusions and recommendations unique to Mongolia. A second objective was to apply these results to everyday obstetric practices within Mongolia and advance the state of prenatal care for all Mongolian women. Methods: Obstetric History: The obstetric history was recorded, and serum biomarkers were measured in 415 pregnancies.The degree of risk for trisomy 21 and other fetal aneuploidy were calculated using maternal age, the results of maternal serum pregnancy-associated plasma protein-A, free beta human chorionic gonadotropin, and fetal nuchal t...
Ultrasound in Obstetrics & Gynecology, 2001
ObjectiveTo examine the effectiveness of screening for trisomy 21 by a combination of maternal age and fetal nuchal translucency thickness at 10–14 weeks of gestation in Germany, Austria and Switzerland.To examine the effectiveness of screening for trisomy 21 by a combination of maternal age and fetal nuchal translucency thickness at 10–14 weeks of gestation in Germany, Austria and Switzerland.MethodsThis was a multicenter study of screening for trisomy 21 by a combination of maternal age and fetal nuchal translucency thickness at 10–14 weeks of gestation. All the sonographers involved in the study had received The Fetal Medicine Foundation Certificate of Competence in the 10–14-week scan. Fetal nuchal translucency thickness and crown–rump length were measured in 23 805 singleton pregnancies with live fetuses. In each case the risk for trisomy 21 was estimated on the basis of maternal age and fetal nuchal translucency thickness for crown–rump length with the use of The Fetal Medicine Foundation's software. The distribution of estimated risk was determined and the sensitivity and false-positive rate for a risk cut-off of 1 in 300 was calculated.This was a multicenter study of screening for trisomy 21 by a combination of maternal age and fetal nuchal translucency thickness at 10–14 weeks of gestation. All the sonographers involved in the study had received The Fetal Medicine Foundation Certificate of Competence in the 10–14-week scan. Fetal nuchal translucency thickness and crown–rump length were measured in 23 805 singleton pregnancies with live fetuses. In each case the risk for trisomy 21 was estimated on the basis of maternal age and fetal nuchal translucency thickness for crown–rump length with the use of The Fetal Medicine Foundation's software. The distribution of estimated risk was determined and the sensitivity and false-positive rate for a risk cut-off of 1 in 300 was calculated.ResultsFetal nuchal translucency thickness was successfully measured in all 23 805 pregnancies and outcome was available in 21 959. The median maternal age was 33 (range 15–49) years and in 7935 (36.1%) the age was 35 years or greater. The median gestation at screening was 12 (10–14) weeks and the median fetal crown–rump length was 61 (range 38–84) mm. The estimated risk for trisomy 21 based on maternal age and fetal nuchal translucency thickness for crown–rump length was 1 in 300 or greater in 13.0% (2800 of 21 475) normal pregnancies, in 87.6% (184 of 210) of those with trisomy 21 and in 87.2% (239 of 274) with other chromosomal defects.Fetal nuchal translucency thickness was successfully measured in all 23 805 pregnancies and outcome was available in 21 959. The median maternal age was 33 (range 15–49) years and in 7935 (36.1%) the age was 35 years or greater. The median gestation at screening was 12 (10–14) weeks and the median fetal crown–rump length was 61 (range 38–84) mm. The estimated risk for trisomy 21 based on maternal age and fetal nuchal translucency thickness for crown–rump length was 1 in 300 or greater in 13.0% (2800 of 21 475) normal pregnancies, in 87.6% (184 of 210) of those with trisomy 21 and in 87.2% (239 of 274) with other chromosomal defects.ConclusionsIn Germany, Austria and Switzerland the results of screening for chromosomal defects by measurement of fetal nuchal translucency thickness, in centers with appropriately qualified sonographers and using The Fetal Medicine Foundation's software, are similar to those reported in the UK using the same methodology.Copyright © 2001 International Society of Ultrasound in Obstetrics and GynecologyIn Germany, Austria and Switzerland the results of screening for chromosomal defects by measurement of fetal nuchal translucency thickness, in centers with appropriately qualified sonographers and using The Fetal Medicine Foundation's software, are similar to those reported in the UK using the same methodology.Copyright © 2001 International Society of Ultrasound in Obstetrics and Gynecology
Analysis of quality of nuchal translucency measurements: its role in prenatal diagnosis
2012
Objective. Quantitative analysis of the quality of nuchal translucency (NT) measurements. Methods. First-trimester combined screening for Down syndrome was performed to all pregnant women attended in our Department from October 2003 to November 2009. NT was measured according to the Fetal Medicine Foundation (FMF) criteria by 20 trained obstetricians. The performance of NT measurements was retrospectively analyzed with regard to several quality control standards. Accuracy according to experience, professional profile, crown rump length (CRL) values, and FMF certification was statistically tested. Results. A total of 14978 NT measurements were assessed. (1) The mean operator-specific median NT-MoM values was 0,98. (2) Mean percentage of cases >95th and <5th centiles were 5,0% and 4,2%, respectively. (3) Logarithmic mean and SD of the NT MoM values were 0,00 and 0,13, respectively. (4) The DR for trisomy 21 at screening time was 90,7% for a FPR of 6,7% for standard screening strategy. (5) According to Cumulative SUM (CUSUM) figures, the performance was more acceptable in FMF-certified operators. Conclusion. Overall, quality standards show optimal NT measurements in our unit. Operator experience, a dedicated profile to fetal medicine, CRL over 60 mm, and FMF certification have a significant positive impact on the quality standards.
P31.04: Nuchal translucency for aneuploidies: single center experience in Brazil
Ultrasound in Obstetrics and Gynecology, 2007
Introduction: First trimester screening for aneuploidy has been proposed as a major improvement because of higher detection rates and an earlier gestational age at diagnosis. Objectives: To evaluate the possible influence of first trimester examination on the time of diagnosis in cases with trisomy 21 in a referral center. Methods: Retrospective database analysis of all cases with trisomy 21 over a 4-year period (2003-2006). The studied population consisted of patients referred for targeted ultrasound examinations at different weeks, including patients with suspected or externally diagnosed aneuploidies. Results: A total of 160 fetuses with trisomy 21 were identified. Of those, 40 (25%), 37 (23.1%), 37 (23.1%) and 46 (28.8%) were diagnosed < 13 + 6 weeks, at 15 to 18 weeks, 19 to 22 weeks and > 22 weeks, respectively. Maternal age in the first three groups was significantly higher than in the group with late referral (37.1 vs. 34.9 years). In the first trimester, 38% of cases were diagnosed after screening in our center and 62% were referred for suspicious findings or confirmed trisomy 21. Second trimester diagnosis was 21.6% and 13.6% after screening, compared to 78.4% and 86.4% referred for suspected or diagnosed trisomy 21 at 15 to 18 weeks and 19 to 22 weeks, respectively. All cases with late referral had ultrasound abnormalities. Conclusion: Despite an increasing proportion of first trimester examinations performed at centers and by local obstetricians, the vast majority of cases with trisomy 21 are still diagnosed in the second trimester. Cases in the high risk population are detected earlier, as these patients receive targeted ultrasound examination in the first and early second trimester.
Bjog-an International Journal of Obstetrics and Gynaecology, 1999
Objectives To evaluate first trimester pregnancy screening for fetal aneuploidy and congenital heart defects by maternal age and nuchal translucency measurement and screening for fetal aneuploidies and congenital heart defects by ultrasound in an unselected population.Design A prospective study.Setting Fetal medicine unit, St George's Hospital, London.Sample 4523 consecutive viable fetuses at 10–14 weeks with a crown–rump length between 38 and 80 mm were scanned transabdominally (93%) or transvaginally (7%).Methods Screening was performed by calculating the background risk from maternal age, gestational age and obstetric history, which was then adjusted with the nuchal translucency measurement in relation to crown–rump length (adjusted risk).Main outcome measures Measurements of crown–rump length and nuchal translucency thickness. An adjusted risk of > 1:270 was considered as a positive screening test. Pregnancy outcome was obtained through karyotyping, outcome questionnaires and examination of the newborn infants.Results Mean maternal age was 29.4 years and mean gestational age 12.2 weeks. Screening was positive in 230/4523 fetuses (5.1%), when the adjusted risk (mean 1:2649) was > 1:270. Fetal karyotype was abnormal in 23 (0.51%) cases, including twelve with trisomy 21, five trisomy 18, one trisomy 13, one trisomy 10, one monosomy X and two triploidies. For a false positive rate of 4.7%, the sensitivity of this test was 78% in detecting any fetal aneuploidy. Only one out of nine major congenital heart defects in this population was found within the 110 euploid fetuses with increased nuchal translucency thickness (> 2.5 mm).Conclusion Screening for fetal aneuploidy by maternal age and nuchal translucency measurement can be effective in an unselected population. However, our results do not support its effectiveness in the detection of cardiac abnormalities.