Nuchal Translucency Measurement

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A. Herman - One of the best experts on this subject based on the ideXlab platform.

  • down s syndrome screening in twin pregnancies by Nuchal Translucency Measurement current concept
    Minerva ginecologica, 2002
    Co-Authors: Ron Maymon, E Jauniaux, A. Herman
    Abstract:

    : During the last 2 decades various non-invasive Down syndrome (DS) screening methods were introduced in clinical practice. However, specific problems were encountered when these methods were applied for twin pregnancies. The current review aims to explore the problematic issue of antenatal DS screening in twins. The implication and the adjusted management in the attempt to achieve the best evaluation for this type of gestation is discussed. Overall more women with twin pregnancies (mainly those who conceived via assisted reproduction) are found false positive for DS. This is because the standard screening algorithms include maternal age. In addition, mid-trimester maternal serum screening is associated with a higher false positive rate; secondary to changes in the feto-placental endocrinologic metabolism in assisted conception pregnancies. Therefore, in twins mid-trimester maternal serum screening is of limited clinical value. In those pregnancies, DS screening by means of Nuchal Translucency Measurements at 10-14 weeks is associated with a lower false positive rate than mid-trimester serum screening. In addition, this screening method enables to specifically identify those fetuses at risk of DS and other anomalies, and thus contributes to a better outcome.

  • Down syndrome screening in multiple pregnancies by Nuchal Translucency Measurement
    The Ultrasound Review of Obstetrics & Gynecology, 2001
    Co-Authors: R. Maymon, A. Herman
    Abstract:

    ABSTRACTVarious non-invasive screening methods for Down syndrome have been introduced in clinical practice during the last two decades. Specific problems were encountered when these methods were applied for multiple pregnancies (twins and high-order multiples). The aim of the current review is to explore these issues and propose an adjusted methodological approach for this highly selected population. Overall, more women with twin pregnancies (mainly those who conceived via assisted reproduction) are found to be false-positive for Down syndrome. This is because the standard screening algorithms include maternal age. In addition, mid-trimester maternal serum screening is associated with a higher false-positive rate, secondary to changes in the fetoplacental endocrinologic metabolism in assisted reproduction pregnancies. Therefore, in multiple pregnancies, mid-trimester maternal serum screening is of limited clinical value. In those pregnancies, screening for Down syndrome by means of Nuchal Translucency mea...

  • Nuchal Translucency Measurement and pregnancy outcome after assisted conception versus spontaneously conceived twins
    Human Reproduction, 2001
    Co-Authors: Ron Maymon, Eric Jauniaux, A Holmes, Yifat Wiener, E Dreazen, A. Herman
    Abstract:

    BACKGROUND: Nuchal Translucency (NT) Measurement for Down's syndrome screening or detecting various fetal anomalies is a reliable sonographic marker. This study evaluates the contribution of NT screening in spontaneously conceived and assisted conception twin pregnancies. METHODS AND RESULTS: Maternal age at Measurement, chorionicity, ultrasound features, karyotype results and pregnancy outcome were recorded prospectively and compared in 83 assisted reproduction treatment and 91 spontaneously conceived twins. Pregnancy outcome was evaluated according to maternal age, method of conception, NT data and chorionicity. NT Measurements (> or =95 centiles of the normal range) were considered screen-positive and mid-pregnancy fetal karyotyping was advised. Complicated pregnancy outcome, which could be signalled by increased NT, was defined as either chromosomal abnormalities, severe structural defects or fetal demise. Based on NT Measurements, 16 fetuses (4.6%) were found to be screen-positive. Five of them had chromosomal aneuploidy and selective termination was performed. The parents also opted for this procedure in another five fetuses because of major structural abnormality diagnosed during NT assessment. No other chromosomal or major fetal abnormality were found post-natally. Although no difference was found in NT, crown-rump length and maternal age between spontaneous and assisted reproduction technology twin pregnancies, the former group had a significantly higher rate of screen-positive results (7 versus 2%, P = 0.047), amniocentesis uptake (33 versus 22%, P = 0.014), monochorionic twining (32 versus 4%, P = 0.001) and complicated pregnancy outcome (11 versus 5%, P = 0.02). CONCLUSION: The present study confirms that first trimester target scanning can improve outcome by early detection and management of cases with an anomalous co-twin. It also identifies some differences between spontaneously and artificially conceived twin pregnancies in relation to this area of testing.

  • On-to-on versus on-to-out Nuchal Translucency Measurements.
    Ultrasound in Obstetrics & Gynecology, 2000
    Co-Authors: A. Herman, E Dreazen, Zwi Weinraub, A. Samandarov, Yan Bukovsky, Ron Maymon
    Abstract:

    Objective To analyze variables affecting the differences between on-to-on and on-to-out methods of Nuchal Translucency Measurement. Design Prospective comparison of two methods of caliper placement. Subjects A total of 245 women undergoing transabdominal and 37 women undergoing transvaginal Nuchal Translucency scanning. Methods Nuchal Translucency was measured using both on-to-on and on-to-out methods of caliper placement on the same frozen images. Differences between the methods were evaluated according to fetal size, Nuchal thickness and mode of examination. Regression analysis was performed for the calculation of the expected difference between the methods at various combinations. Results among 1254 singleton pregnancies were used to set 50th, 95th and 97.5th centiles for the on-to-on method. The calculated differences were used to set 50th, 95th and 97.5th centiles for the on-to-out method. Results The mean difference between on-to-out and on-to-on Nuchal Translucency, using transabdominal scanning, was 0.95 ± 0.14 mm. The differences were shown to correlate directly with fetal size and with Nuchal thickness. In addition, scans performed transvaginally exhibited a smaller difference between the methods (0.90 mm vs. 0.94 mm; P 

  • comparison of Nuchal Translucency Measurement and mid gestation serum screening in assisted reproduction versus naturally conceived singleton pregnancies
    Prenatal Diagnosis, 1999
    Co-Authors: Ron Maymon, E Dreazen, Ian Bukovsky, Z Weinraub, S Rozinsky, A. Herman
    Abstract:

    It has been reported that second-trimester serum markers may be affected by assisted reproduction leading to a higher false-positive rate. The current study compares 10–14 week Nuchal Translucency (NT) Measurement and early mid-trimester serum screening in pregnancies resulting from assisted reproduction versus naturally conceived pregnancies. 75 pregnant women with a singleton pregnancy achieved by assisted reproduction underwent both 10–14 weeks NT Measurement and second-trimester triple test and were followed throughout gestation. They were compared with matched controls for gestation and maternal ages. A risk of 1:380 or higher or having a fetus with Down syndrome was considered as screen-positive in both tests. The mean maternal age (30±3 years) and crown–rump length (61±9 mm) were similar, and there was no difference in NT thickness distribution between the groups. Based on NT Measurement, 4 (5 per cent) women in the study and 2 (3 per cent) in the control groups, were defined as screen positive (p=NS). However, 11 (15 per cent) women in the study group and 4 (5 per cent) in the control group were found screen-positive by the triple test (p<0.05). A significantly higher amniocentesis rate of 20 per cent was noted in the study group compared with 8 per cent in the controls (p<0.05). All karyotypes were normal and no miscarriages or structural malformation were diagnosed in either group. We confirm the observation that assisted reproduction may adversely affect second-trimester screening results, which did not affect the NT screening test. Since these series are relatively small, larger series may be needed to clarify the most beneficial screening policy for this highly selected group of pregnant women. Copyright © 1999 John Wiley & Sons, Ltd.

Ron Maymon - One of the best experts on this subject based on the ideXlab platform.

  • down s syndrome screening in twin pregnancies by Nuchal Translucency Measurement current concept
    Minerva ginecologica, 2002
    Co-Authors: Ron Maymon, E Jauniaux, A. Herman
    Abstract:

    : During the last 2 decades various non-invasive Down syndrome (DS) screening methods were introduced in clinical practice. However, specific problems were encountered when these methods were applied for twin pregnancies. The current review aims to explore the problematic issue of antenatal DS screening in twins. The implication and the adjusted management in the attempt to achieve the best evaluation for this type of gestation is discussed. Overall more women with twin pregnancies (mainly those who conceived via assisted reproduction) are found false positive for DS. This is because the standard screening algorithms include maternal age. In addition, mid-trimester maternal serum screening is associated with a higher false positive rate; secondary to changes in the feto-placental endocrinologic metabolism in assisted conception pregnancies. Therefore, in twins mid-trimester maternal serum screening is of limited clinical value. In those pregnancies, DS screening by means of Nuchal Translucency Measurements at 10-14 weeks is associated with a lower false positive rate than mid-trimester serum screening. In addition, this screening method enables to specifically identify those fetuses at risk of DS and other anomalies, and thus contributes to a better outcome.

  • Nuchal Translucency Measurement and pregnancy outcome after assisted conception versus spontaneously conceived twins
    Human Reproduction, 2001
    Co-Authors: Ron Maymon, Eric Jauniaux, A Holmes, Yifat Wiener, E Dreazen, A. Herman
    Abstract:

    BACKGROUND: Nuchal Translucency (NT) Measurement for Down's syndrome screening or detecting various fetal anomalies is a reliable sonographic marker. This study evaluates the contribution of NT screening in spontaneously conceived and assisted conception twin pregnancies. METHODS AND RESULTS: Maternal age at Measurement, chorionicity, ultrasound features, karyotype results and pregnancy outcome were recorded prospectively and compared in 83 assisted reproduction treatment and 91 spontaneously conceived twins. Pregnancy outcome was evaluated according to maternal age, method of conception, NT data and chorionicity. NT Measurements (> or =95 centiles of the normal range) were considered screen-positive and mid-pregnancy fetal karyotyping was advised. Complicated pregnancy outcome, which could be signalled by increased NT, was defined as either chromosomal abnormalities, severe structural defects or fetal demise. Based on NT Measurements, 16 fetuses (4.6%) were found to be screen-positive. Five of them had chromosomal aneuploidy and selective termination was performed. The parents also opted for this procedure in another five fetuses because of major structural abnormality diagnosed during NT assessment. No other chromosomal or major fetal abnormality were found post-natally. Although no difference was found in NT, crown-rump length and maternal age between spontaneous and assisted reproduction technology twin pregnancies, the former group had a significantly higher rate of screen-positive results (7 versus 2%, P = 0.047), amniocentesis uptake (33 versus 22%, P = 0.014), monochorionic twining (32 versus 4%, P = 0.001) and complicated pregnancy outcome (11 versus 5%, P = 0.02). CONCLUSION: The present study confirms that first trimester target scanning can improve outcome by early detection and management of cases with an anomalous co-twin. It also identifies some differences between spontaneously and artificially conceived twin pregnancies in relation to this area of testing.

  • On-to-on versus on-to-out Nuchal Translucency Measurements.
    Ultrasound in Obstetrics & Gynecology, 2000
    Co-Authors: A. Herman, E Dreazen, Zwi Weinraub, A. Samandarov, Yan Bukovsky, Ron Maymon
    Abstract:

    Objective To analyze variables affecting the differences between on-to-on and on-to-out methods of Nuchal Translucency Measurement. Design Prospective comparison of two methods of caliper placement. Subjects A total of 245 women undergoing transabdominal and 37 women undergoing transvaginal Nuchal Translucency scanning. Methods Nuchal Translucency was measured using both on-to-on and on-to-out methods of caliper placement on the same frozen images. Differences between the methods were evaluated according to fetal size, Nuchal thickness and mode of examination. Regression analysis was performed for the calculation of the expected difference between the methods at various combinations. Results among 1254 singleton pregnancies were used to set 50th, 95th and 97.5th centiles for the on-to-on method. The calculated differences were used to set 50th, 95th and 97.5th centiles for the on-to-out method. Results The mean difference between on-to-out and on-to-on Nuchal Translucency, using transabdominal scanning, was 0.95 ± 0.14 mm. The differences were shown to correlate directly with fetal size and with Nuchal thickness. In addition, scans performed transvaginally exhibited a smaller difference between the methods (0.90 mm vs. 0.94 mm; P 

  • comparison of Nuchal Translucency Measurement and mid gestation serum screening in assisted reproduction versus naturally conceived singleton pregnancies
    Prenatal Diagnosis, 1999
    Co-Authors: Ron Maymon, E Dreazen, Ian Bukovsky, Z Weinraub, S Rozinsky, A. Herman
    Abstract:

    It has been reported that second-trimester serum markers may be affected by assisted reproduction leading to a higher false-positive rate. The current study compares 10–14 week Nuchal Translucency (NT) Measurement and early mid-trimester serum screening in pregnancies resulting from assisted reproduction versus naturally conceived pregnancies. 75 pregnant women with a singleton pregnancy achieved by assisted reproduction underwent both 10–14 weeks NT Measurement and second-trimester triple test and were followed throughout gestation. They were compared with matched controls for gestation and maternal ages. A risk of 1:380 or higher or having a fetus with Down syndrome was considered as screen-positive in both tests. The mean maternal age (30±3 years) and crown–rump length (61±9 mm) were similar, and there was no difference in NT thickness distribution between the groups. Based on NT Measurement, 4 (5 per cent) women in the study and 2 (3 per cent) in the control groups, were defined as screen positive (p=NS). However, 11 (15 per cent) women in the study group and 4 (5 per cent) in the control group were found screen-positive by the triple test (p<0.05). A significantly higher amniocentesis rate of 20 per cent was noted in the study group compared with 8 per cent in the controls (p<0.05). All karyotypes were normal and no miscarriages or structural malformation were diagnosed in either group. We confirm the observation that assisted reproduction may adversely affect second-trimester screening results, which did not affect the NT screening test. Since these series are relatively small, larger series may be needed to clarify the most beneficial screening policy for this highly selected group of pregnant women. Copyright © 1999 John Wiley & Sons, Ltd.

  • the feasibility of Nuchal Translucency Measurement in higher order multiple gestations achieved by assisted reproduction
    Human Reproduction, 1999
    Co-Authors: Ron Maymon, E Dreazen, Y Tovbin, Ian Bukovsky, Z Weinraub, A. Herman
    Abstract:

    : Nuchal Translucency (NT) Measurement for screening chromosomal abnormalities and detecting fetal anomalies is an effective ultrasonographic marker, originally developed for singleton pregnancies. This study sought to evaluate the feasibility of NT Measurements in higher order multiple gestations. Pregnant patients who conceived following assisted reproduction and were carrying three or more fetuses were enrolled in the study. Each fetus was ultrasonographically assessed, a NT Measurement was obtained, and the findings were used for counselling prior to any invasive procedure. In all, 24 pregnant patients, initially carrying 79 fetuses aged 10-14 weeks of gestation, were compared with 79 consecutively matched, singleton controls, naturally conceived, having similar crown-rump lengths (+/- 3 mm). NT Measurements were feasible for both study and control fetuses, which exhibited similar NT Measurements for 5th, 50th and 95th centiles. Also, mean NT thicknesses [Measurements in mm or multiple of the medians (MOM)] were similar for both groups (1.41 +/- 0.41 and 1.35 +/- 0.39 mm respectively and 0.87 +/- 0.23 and 0.83 +/- 0.25 MOM respectively). Prenatally no chromosomal abnormalities were detected in either group, and, of those infants who had no karyotyping, no traits were observed that warranted chromosomal analysis. NT Measurements are feasible in higher order multiple gestations. Since there is no other effective screening modality for these pregnancies, it seems reasonable to recommend NT Measurement for antenatal screening services for higher order multiple gestations.

E Dreazen - One of the best experts on this subject based on the ideXlab platform.

  • Nuchal Translucency Measurement and pregnancy outcome after assisted conception versus spontaneously conceived twins
    Human Reproduction, 2001
    Co-Authors: Ron Maymon, Eric Jauniaux, A Holmes, Yifat Wiener, E Dreazen, A. Herman
    Abstract:

    BACKGROUND: Nuchal Translucency (NT) Measurement for Down's syndrome screening or detecting various fetal anomalies is a reliable sonographic marker. This study evaluates the contribution of NT screening in spontaneously conceived and assisted conception twin pregnancies. METHODS AND RESULTS: Maternal age at Measurement, chorionicity, ultrasound features, karyotype results and pregnancy outcome were recorded prospectively and compared in 83 assisted reproduction treatment and 91 spontaneously conceived twins. Pregnancy outcome was evaluated according to maternal age, method of conception, NT data and chorionicity. NT Measurements (> or =95 centiles of the normal range) were considered screen-positive and mid-pregnancy fetal karyotyping was advised. Complicated pregnancy outcome, which could be signalled by increased NT, was defined as either chromosomal abnormalities, severe structural defects or fetal demise. Based on NT Measurements, 16 fetuses (4.6%) were found to be screen-positive. Five of them had chromosomal aneuploidy and selective termination was performed. The parents also opted for this procedure in another five fetuses because of major structural abnormality diagnosed during NT assessment. No other chromosomal or major fetal abnormality were found post-natally. Although no difference was found in NT, crown-rump length and maternal age between spontaneous and assisted reproduction technology twin pregnancies, the former group had a significantly higher rate of screen-positive results (7 versus 2%, P = 0.047), amniocentesis uptake (33 versus 22%, P = 0.014), monochorionic twining (32 versus 4%, P = 0.001) and complicated pregnancy outcome (11 versus 5%, P = 0.02). CONCLUSION: The present study confirms that first trimester target scanning can improve outcome by early detection and management of cases with an anomalous co-twin. It also identifies some differences between spontaneously and artificially conceived twin pregnancies in relation to this area of testing.

  • On-to-on versus on-to-out Nuchal Translucency Measurements.
    Ultrasound in Obstetrics & Gynecology, 2000
    Co-Authors: A. Herman, E Dreazen, Zwi Weinraub, A. Samandarov, Yan Bukovsky, Ron Maymon
    Abstract:

    Objective To analyze variables affecting the differences between on-to-on and on-to-out methods of Nuchal Translucency Measurement. Design Prospective comparison of two methods of caliper placement. Subjects A total of 245 women undergoing transabdominal and 37 women undergoing transvaginal Nuchal Translucency scanning. Methods Nuchal Translucency was measured using both on-to-on and on-to-out methods of caliper placement on the same frozen images. Differences between the methods were evaluated according to fetal size, Nuchal thickness and mode of examination. Regression analysis was performed for the calculation of the expected difference between the methods at various combinations. Results among 1254 singleton pregnancies were used to set 50th, 95th and 97.5th centiles for the on-to-on method. The calculated differences were used to set 50th, 95th and 97.5th centiles for the on-to-out method. Results The mean difference between on-to-out and on-to-on Nuchal Translucency, using transabdominal scanning, was 0.95 ± 0.14 mm. The differences were shown to correlate directly with fetal size and with Nuchal thickness. In addition, scans performed transvaginally exhibited a smaller difference between the methods (0.90 mm vs. 0.94 mm; P 

  • comparison of Nuchal Translucency Measurement and mid gestation serum screening in assisted reproduction versus naturally conceived singleton pregnancies
    Prenatal Diagnosis, 1999
    Co-Authors: Ron Maymon, E Dreazen, Ian Bukovsky, Z Weinraub, S Rozinsky, A. Herman
    Abstract:

    It has been reported that second-trimester serum markers may be affected by assisted reproduction leading to a higher false-positive rate. The current study compares 10–14 week Nuchal Translucency (NT) Measurement and early mid-trimester serum screening in pregnancies resulting from assisted reproduction versus naturally conceived pregnancies. 75 pregnant women with a singleton pregnancy achieved by assisted reproduction underwent both 10–14 weeks NT Measurement and second-trimester triple test and were followed throughout gestation. They were compared with matched controls for gestation and maternal ages. A risk of 1:380 or higher or having a fetus with Down syndrome was considered as screen-positive in both tests. The mean maternal age (30±3 years) and crown–rump length (61±9 mm) were similar, and there was no difference in NT thickness distribution between the groups. Based on NT Measurement, 4 (5 per cent) women in the study and 2 (3 per cent) in the control groups, were defined as screen positive (p=NS). However, 11 (15 per cent) women in the study group and 4 (5 per cent) in the control group were found screen-positive by the triple test (p<0.05). A significantly higher amniocentesis rate of 20 per cent was noted in the study group compared with 8 per cent in the controls (p<0.05). All karyotypes were normal and no miscarriages or structural malformation were diagnosed in either group. We confirm the observation that assisted reproduction may adversely affect second-trimester screening results, which did not affect the NT screening test. Since these series are relatively small, larger series may be needed to clarify the most beneficial screening policy for this highly selected group of pregnant women. Copyright © 1999 John Wiley & Sons, Ltd.

  • the feasibility of Nuchal Translucency Measurement in higher order multiple gestations achieved by assisted reproduction
    Human Reproduction, 1999
    Co-Authors: Ron Maymon, E Dreazen, Y Tovbin, Ian Bukovsky, Z Weinraub, A. Herman
    Abstract:

    : Nuchal Translucency (NT) Measurement for screening chromosomal abnormalities and detecting fetal anomalies is an effective ultrasonographic marker, originally developed for singleton pregnancies. This study sought to evaluate the feasibility of NT Measurements in higher order multiple gestations. Pregnant patients who conceived following assisted reproduction and were carrying three or more fetuses were enrolled in the study. Each fetus was ultrasonographically assessed, a NT Measurement was obtained, and the findings were used for counselling prior to any invasive procedure. In all, 24 pregnant patients, initially carrying 79 fetuses aged 10-14 weeks of gestation, were compared with 79 consecutively matched, singleton controls, naturally conceived, having similar crown-rump lengths (+/- 3 mm). NT Measurements were feasible for both study and control fetuses, which exhibited similar NT Measurements for 5th, 50th and 95th centiles. Also, mean NT thicknesses [Measurements in mm or multiple of the medians (MOM)] were similar for both groups (1.41 +/- 0.41 and 1.35 +/- 0.39 mm respectively and 0.87 +/- 0.23 and 0.83 +/- 0.25 MOM respectively). Prenatally no chromosomal abnormalities were detected in either group, and, of those infants who had no karyotyping, no traits were observed that warranted chromosomal analysis. NT Measurements are feasible in higher order multiple gestations. Since there is no other effective screening modality for these pregnancies, it seems reasonable to recommend NT Measurement for antenatal screening services for higher order multiple gestations.

  • comparison of Nuchal Translucency Measurement and second trimester triple serum screening in twin versus singleton pregnancies
    Prenatal Diagnosis, 1999
    Co-Authors: Ron Maymon, E Dreazen, Ian Bukovsky, Z Weinraub, S Rozinsky, A. Herman
    Abstract:

    : Maternal serum screening for Down syndrome (DS) in twin pregnancies poses difficulties due to a lack of precise biochemical information about each co-twin. The current study attempts, for the first time, to compare two screening methods: Nuchal Translucency (NT) Measurement and serum screening for DS, in twin pregnancies. 60 women with twin pregnancies (study group) underwent both first-trimester NT scanning and mid-trimester triple-marker serum screening, and were followed throughout their gestation. Nuchal Translucency Measurements were compared with a matched control of 120 singleton pregnancies with a similar (+/-2 years) maternal age and fetal crown-rump length (CRL) (+/-3 mm). In both analyses, a risk of 1:380, or higher, of having a DS newborn was considered screen positive. Both mean maternal age (31+/-3 years) and CRL (62+/-11 mm) were similar in the study and control groups. The median NT Measurement expressed as multiples of the median (MOM) for CRL was similar in the study and control groups (0.85 and 0.88, respectively). Based on NT Measurements, 5 per cent of the pregnancies in the study group and 2.5 per cent in the control group were defined as screen positive (p =N. S). Mid-gestation serum screening was associated with 15 per cent and 6 per cent screen-positive rate in study and control groups, respectively (p<0. 05). There was a ratio of 1:3 screen-positive rate between first and second-trimester screening tests within the study group. This high false-positive rate results led to 18.3 per cent amniocentesis rate in the study group compared with 7.5 per cent of the control group (p<0.03). Only one co-twin which was picked up by the NT screen was further diagnosed as trisomy 21, and one co-twin with cardiac and neural tube defect was missed by the two screening tests and was later picked up in an anomaly scan. Although the current series is too small to provoke any changes in screening practice, when twin pregnancies are diagnosed, it seems very reasonable to offer them NT Measurement. A larger group may be needed to clarify which approach is the most beneficial screening policy for this highly selected group of pregnant women.

D L Economides - One of the best experts on this subject based on the ideXlab platform.

  • the use of Nuchal Translucency Measurement and second trimester biochemical markers in screening for down s syndrome
    British Journal of Obstetrics and Gynaecology, 2001
    Co-Authors: G D Michailidis, Kevin Spencer, D L Economides
    Abstract:

    Objective To assess the effectiveness of antenatal screening for trisomy 21 by first trimester sonography followed by second trimester biochemical screening. Design Retrospective five-year review. Setting Maternity unit of a university hospital. Population An unselected group of 7447 pregnant women who had a first trimester scan and Nuchal Translucency Measurement in our unit after January 1995 and had an estimated date of delivery before 1 January 2000. 11.9% were ≥ 37 years old. A subgroup (n=4864) also had second trimester biochemical testing by alpha-fetoprotein and free β-human chorionic gonadotrophin. Main outcome measures Prenatal and postnatal diagnosis of trisomy 21. Results There were 23 fetuses affected with trisomy 21. The overall prenatal detection rate was 87% (20/23; 95% CI 66% to 97%) and we performed invasive procedures in 8.5% of our population. First trimester sonography identified 74% (95% CI 51.6% to 89.8%) of affected fetuses. Second trimester biochemical screening detected half of the fetuses with trisomy 21 which were missed by first trimester screening, increasing the sensitivity to 90.5% (19/21; 95% CI 69.6% to 98.8%) for an invasive procedure rate of 4.2% performed in screened positive women. However, the positive predictive value of the biochemical test was very low (0.5%). In screen negative women, karyotyping for advanced maternal age did not detect any affected fetuses. Conclusion First trimester Nuchal Translucency Measurement is an effective screening test for the prenatal detection of fetuses with Down's Syndrome. Although the Measurement of biochemical markers in the second trimester can detect additional affected fetuses this may be outweighed by the delay in diagnosis, the extra visits and cost so that the right time for biochemical screening is most likely to be in the first trimester.

  • Nuchal Translucency Measurement and pregnancy outcome in karyotypically normal fetuses
    Ultrasound in Obstetrics & Gynecology, 2001
    Co-Authors: G D Michailidis, D L Economides
    Abstract:

    Objective The aim of the study was to evaluate the use of Nuchal Translucency Measurement as a marker of adverse pregnancy outcome in karyotypically normal fetuses. Methods During the years 1995-99, Nuchal Translucency (NT) Measurement was routinely offered to all women who had their dating scan in our unit. From the data collected we calculated the 95th and 99th centiles of the NT for a given crown-rump length using regression analysis. The NT Measurements were analyzed in relation to Pregnancy outcome, especially with regards to miscarriage, intrauterine death and diagnosis of fetal structural abnormalities, after excluding chromosomal abnormalities. Results The pregnancy outcome was available in 6650 (89%) of the 7500 pregnancies. In fetuses with an NT over the 99th centile, 17.8% (relative risk 12.2, 95% CI 7.2-20.8) had an adverse pregnancy outcome (miscarriage, intrauterine death, or termination for fetal abnormality) versus 1.5% for those with a normal Measurement. The incidence of structural abnormalities, especially heart defects, was significantly increased in the high-NT groups. Three out of 11 fetuses with major cardiac abnormalities had an NT Measurement over the 99th centile. The calculated relative risk for major heart defects in fetuses with increased NT was 33.5 (95% CT 9-123). Conclusion In the setting of routine antenatal screening, an increased NT Measurement is a marker of a high-risk pregnancy evert in karyotypically normal fetuses. In addition, the increased incidence of structural abnormalities makes the close follow-up of these pregnancies imperative and should include specialized fetal echocardiography

  • p63the effect of fetal neck position on Nuchal Translucency Measurement
    Ultrasound in Obstetrics & Gynecology, 2000
    Co-Authors: I Chatzipapas, Y Spathopoulos, B J Whitlow, D L Economides
    Abstract:

    Background The aim of this study was to determine whether the position of the fetal neck has a significant effect on Nuchal Translucency Measurement (NT). Method A prospective cross-sectional study was carried out. One hundred and ninety-six women from an unselected population underwent transabdominal sonography. The Nuchal Translucency was measured in the mid-sagittal plane, with the fetal neck in the flexed, neutral and extended positions. Measurement was taken to the nearest 0.1 mm. Statistical analysis using a paired t-test for the differences in the extended and neutral position Nuchal Translucency [delta extended NT] and in the flexed and neutral position Nuchal Translucency [delta flexed NT] was performed. Results On average the extended NT was 0.62 mm greater than the neutral NT value [95% confidence interval 0.53–0.70, T = 14.33, P = < 0.00001]. The flexed NT was on average 0.40 mm less than the neutral NT value [95% confidence interval 0.34–0.47, T = 11.99, P = < 0.00001]. The repeatability coefficient was lower in the case of neutral NT Measurement [0.48] and was higher in the other groups [extended = 1.04, flexed = 0.70]. Conclusion The effect of fetal neck position can make a significant difference on Nuchal Translucency Measurement. Repeatability of Measurements are more accurate with the fetal neck in the neutral position. These findings have important implications for clinicians using Nuchal Translucency to screen the general obstetric population.

  • the effect of fetal neck position on Nuchal Translucency Measurement
    British Journal of Obstetrics and Gynaecology, 1998
    Co-Authors: B J Whitlow, I Chatzipapas, D L Economides
    Abstract:

    Objective To determine the influence of the position of the fetal neck on Nuchal Translucency Measurement. Design A prospective cross-sectional study. Population One hundred and ninety-six. Methods Nuchal Translucency was measured in the mid-sagittal plane, with the fetal neck in the flexed, neutral and extended positions. Measurements were made to the nearest 0.1 mm. Statistical analysis used the paired t-test for differences between the extended and neutral positions, [A extended Nuchal Translucency] and the flexed and neutral positions [A flexed Nuchal Translucency]. Results The mean extended Nuchal Translucency was 0.62 mm greater than the mean neutral Nuchal Translucency value [95% confidence interval 0.53 to 0.70, T= 14.33, P 0.000011. The mean flexed Nuchal Translucency was 0.40 mm less than the mean neutral Nuchal Translucency value [95% CI 0.34 to 0.47, T = 11.99; P= < 0.000011. The repeatability coefficient was lower in the case of neutral Nuchal Translucency Measurements [0.48] and was higher in the other groups [extended = 1.04, flexed = 0.701. Conclusion Fetal neck position can make a significant difference to Nuchal Translucency Measurements. Repeatability of Measurements are more accurate with the fetal neck in the neutral position. These findings have important implications for clinicians using Nuchal Translucency to screen the general obstetric population.

  • the effect of Nuchal Translucency Measurement on second trimester biochemical screening for down s syndrome
    Ultrasound in Obstetrics & Gynecology, 1997
    Co-Authors: R A Kadir, D L Economides
    Abstract:

    In this study we examined the effect of introducing first-trimester Nuchal Translucency Measurement on the second-trimester maternal serum screening for trisomy 21. The detection rate, false-positive rate, likelihood ratio and positive predictive value of the double marker test before and after introduction of Nuchal Translucency Measurement were determined. The detection rate of Nuchal Translucency screening for trisomy 21 was 83% (5/6) with a 1.3% false-positive rate, a 63.8 likelihood ratio and a positive predictive value of 22.7%. After the introduction of Nuchal Translucency Measurement, the likelihood ratio for a positive result and positive predictive value of the biochemical screening decreased from 9.1 to 5 and 2.7% to 0.45%, respectively. Our results show that Nuchal Translucency Measurement is not only an effective method of first-trimester screening for Down's syndrome but also has implications for the likelihood ratio and positive predictive value of second-trimester biochemical screening. Since the biochemical test is now applied to a population with a decreased risk of trisomy 21, a positive test will be less likely to indicate Down's syndrome than when Nuchal Translucency Measurement was not applied. Copyright © 1997 International Society of Ultrasound in Obstetrics and Gynecology

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  • comparison of Nuchal Translucency Measurement and mid gestation serum screening in assisted reproduction versus naturally conceived singleton pregnancies
    Prenatal Diagnosis, 1999
    Co-Authors: Ron Maymon, E Dreazen, Ian Bukovsky, Z Weinraub, S Rozinsky, A. Herman
    Abstract:

    It has been reported that second-trimester serum markers may be affected by assisted reproduction leading to a higher false-positive rate. The current study compares 10–14 week Nuchal Translucency (NT) Measurement and early mid-trimester serum screening in pregnancies resulting from assisted reproduction versus naturally conceived pregnancies. 75 pregnant women with a singleton pregnancy achieved by assisted reproduction underwent both 10–14 weeks NT Measurement and second-trimester triple test and were followed throughout gestation. They were compared with matched controls for gestation and maternal ages. A risk of 1:380 or higher or having a fetus with Down syndrome was considered as screen-positive in both tests. The mean maternal age (30±3 years) and crown–rump length (61±9 mm) were similar, and there was no difference in NT thickness distribution between the groups. Based on NT Measurement, 4 (5 per cent) women in the study and 2 (3 per cent) in the control groups, were defined as screen positive (p=NS). However, 11 (15 per cent) women in the study group and 4 (5 per cent) in the control group were found screen-positive by the triple test (p<0.05). A significantly higher amniocentesis rate of 20 per cent was noted in the study group compared with 8 per cent in the controls (p<0.05). All karyotypes were normal and no miscarriages or structural malformation were diagnosed in either group. We confirm the observation that assisted reproduction may adversely affect second-trimester screening results, which did not affect the NT screening test. Since these series are relatively small, larger series may be needed to clarify the most beneficial screening policy for this highly selected group of pregnant women. Copyright © 1999 John Wiley & Sons, Ltd.

  • the feasibility of Nuchal Translucency Measurement in higher order multiple gestations achieved by assisted reproduction
    Human Reproduction, 1999
    Co-Authors: Ron Maymon, E Dreazen, Y Tovbin, Ian Bukovsky, Z Weinraub, A. Herman
    Abstract:

    : Nuchal Translucency (NT) Measurement for screening chromosomal abnormalities and detecting fetal anomalies is an effective ultrasonographic marker, originally developed for singleton pregnancies. This study sought to evaluate the feasibility of NT Measurements in higher order multiple gestations. Pregnant patients who conceived following assisted reproduction and were carrying three or more fetuses were enrolled in the study. Each fetus was ultrasonographically assessed, a NT Measurement was obtained, and the findings were used for counselling prior to any invasive procedure. In all, 24 pregnant patients, initially carrying 79 fetuses aged 10-14 weeks of gestation, were compared with 79 consecutively matched, singleton controls, naturally conceived, having similar crown-rump lengths (+/- 3 mm). NT Measurements were feasible for both study and control fetuses, which exhibited similar NT Measurements for 5th, 50th and 95th centiles. Also, mean NT thicknesses [Measurements in mm or multiple of the medians (MOM)] were similar for both groups (1.41 +/- 0.41 and 1.35 +/- 0.39 mm respectively and 0.87 +/- 0.23 and 0.83 +/- 0.25 MOM respectively). Prenatally no chromosomal abnormalities were detected in either group, and, of those infants who had no karyotyping, no traits were observed that warranted chromosomal analysis. NT Measurements are feasible in higher order multiple gestations. Since there is no other effective screening modality for these pregnancies, it seems reasonable to recommend NT Measurement for antenatal screening services for higher order multiple gestations.

  • comparison of Nuchal Translucency Measurement and second trimester triple serum screening in twin versus singleton pregnancies
    Prenatal Diagnosis, 1999
    Co-Authors: Ron Maymon, E Dreazen, Ian Bukovsky, Z Weinraub, S Rozinsky, A. Herman
    Abstract:

    : Maternal serum screening for Down syndrome (DS) in twin pregnancies poses difficulties due to a lack of precise biochemical information about each co-twin. The current study attempts, for the first time, to compare two screening methods: Nuchal Translucency (NT) Measurement and serum screening for DS, in twin pregnancies. 60 women with twin pregnancies (study group) underwent both first-trimester NT scanning and mid-trimester triple-marker serum screening, and were followed throughout their gestation. Nuchal Translucency Measurements were compared with a matched control of 120 singleton pregnancies with a similar (+/-2 years) maternal age and fetal crown-rump length (CRL) (+/-3 mm). In both analyses, a risk of 1:380, or higher, of having a DS newborn was considered screen positive. Both mean maternal age (31+/-3 years) and CRL (62+/-11 mm) were similar in the study and control groups. The median NT Measurement expressed as multiples of the median (MOM) for CRL was similar in the study and control groups (0.85 and 0.88, respectively). Based on NT Measurements, 5 per cent of the pregnancies in the study group and 2.5 per cent in the control group were defined as screen positive (p =N. S). Mid-gestation serum screening was associated with 15 per cent and 6 per cent screen-positive rate in study and control groups, respectively (p<0. 05). There was a ratio of 1:3 screen-positive rate between first and second-trimester screening tests within the study group. This high false-positive rate results led to 18.3 per cent amniocentesis rate in the study group compared with 7.5 per cent of the control group (p<0.03). Only one co-twin which was picked up by the NT screen was further diagnosed as trisomy 21, and one co-twin with cardiac and neural tube defect was missed by the two screening tests and was later picked up in an anomaly scan. Although the current series is too small to provoke any changes in screening practice, when twin pregnancies are diagnosed, it seems very reasonable to offer them NT Measurement. A larger group may be needed to clarify which approach is the most beneficial screening policy for this highly selected group of pregnant women.

  • Comparison of Nuchal Translucency Measurement and second-trimester triple serum screening in twin versus singleton pregnancies.
    Prenatal Diagnosis, 1999
    Co-Authors: Ron Maymon, E Dreazen, Ian Bukovsky, S Rozinsky, Zwi Weinraub, A. Herman
    Abstract:

    : Maternal serum screening for Down syndrome (DS) in twin pregnancies poses difficulties due to a lack of precise biochemical information about each co-twin. The current study attempts, for the first time, to compare two screening methods: Nuchal Translucency (NT) Measurement and serum screening for DS, in twin pregnancies. 60 women with twin pregnancies (study group) underwent both first-trimester NT scanning and mid-trimester triple-marker serum screening, and were followed throughout their gestation. Nuchal Translucency Measurements were compared with a matched control of 120 singleton pregnancies with a similar (+/-2 years) maternal age and fetal crown-rump length (CRL) (+/-3 mm). In both analyses, a risk of 1:380, or higher, of having a DS newborn was considered screen positive. Both mean maternal age (31+/-3 years) and CRL (62+/-11 mm) were similar in the study and control groups. The median NT Measurement expressed as multiples of the median (MOM) for CRL was similar in the study and control groups (0.85 and 0.88, respectively). Based on NT Measurements, 5 per cent of the pregnancies in the study group and 2.5 per cent in the control group were defined as screen positive (p =N. S). Mid-gestation serum screening was associated with 15 per cent and 6 per cent screen-positive rate in study and control groups, respectively (p

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