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Artigo de Revisão
First-trimester screening for chromosomal abnormalities
Revista Brasileira de Ginecologia e Obstetrícia. 2007;29(12):647-653
03-11-2007
Summary
Artigo de RevisãoFirst-trimester screening for chromosomal abnormalities
Revista Brasileira de Ginecologia e Obstetrícia. 2007;29(12):647-653
03-11-2007DOI 10.1590/S0100-72032007001200008
Views51Screening for major chromosomal abnormalities can be provided in the first trimester of pregnancy. Screening by a combination of fetal nuchal translucency and maternal serum free human chorionic gonadotropin and pregnancy-associated plasma protein-A can identify 90% of fetuses with trisomy 21 and other major chromosomal abnormalities for a false-positive rate of 5%. This is superior to the 30% detection rate achieved by maternal age and 65% by second-trimester maternal serum biochemistry. A further improvement in the effectiveness of first-trimester screening is likely to be achieved by a risk-orientated two-stage approach. In this approach, the patients are subdivided into a high-risk group, requiring invasive testing; a low-risk group, which can be reassured that an abnormality is unlikely, and an intermediate-risk group (risk of 1 in 101 to 1 in 1000), in which further assessment is performed by first-trimester ultrasound examination (for presence/absence of the nasal bone or presence/absence of tricuspid regurgitation or normal/abnormal Doppler velocity waveform in the ductus venosus), and chorionic villus sampling is performed if their adjusted risk becomes 1 in 100 or more. Those performing first-trimester scans should be appropriately trained and their results subjected to external quality assurance. This process was well established by the Fetal Medical Foundation several years ago and is widely accepted internationally.
Key-words Chorionic gonadotropinChromosome aberrationsNuchal translucency measurementPregnancy trimester, firstPregnancy-associated plasma protein-Aprenatal diagnosisUltrasonographySee moreViews51
This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Summary
Artigo de RevisãoFirst-trimester screening for chromosomal abnormalities
Revista Brasileira de Ginecologia e Obstetrícia. 2007;29(12):647-653
03-11-2007DOI 10.1590/S0100-72032007001200008
Views51Screening for major chromosomal abnormalities can be provided in the first trimester of pregnancy. Screening by a combination of fetal nuchal translucency and maternal serum free human chorionic gonadotropin and pregnancy-associated plasma protein-A can identify 90% of fetuses with trisomy 21 and other major chromosomal abnormalities for a false-positive rate of 5%. This is superior to the 30% detection rate achieved by maternal age and 65% by second-trimester maternal serum biochemistry. A further improvement in the effectiveness of first-trimester screening is likely to be achieved by a risk-orientated two-stage approach. In this approach, the patients are subdivided into a high-risk group, requiring invasive testing; a low-risk group, which can be reassured that an abnormality is unlikely, and an intermediate-risk group (risk of 1 in 101 to 1 in 1000), in which further assessment is performed by first-trimester ultrasound examination (for presence/absence of the nasal bone or presence/absence of tricuspid regurgitation or normal/abnormal Doppler velocity waveform in the ductus venosus), and chorionic villus sampling is performed if their adjusted risk becomes 1 in 100 or more. Those performing first-trimester scans should be appropriately trained and their results subjected to external quality assurance. This process was well established by the Fetal Medical Foundation several years ago and is widely accepted internationally.
Key-words Chorionic gonadotropinChromosome aberrationsNuchal translucency measurementPregnancy trimester, firstPregnancy-associated plasma protein-Aprenatal diagnosisUltrasonographySee moreThis is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. -
Artigos Originais
Quantitation of amniotic fluid by three- and two-dimensional ultrasonography during the first trimester of pregnancy
Revista Brasileira de Ginecologia e Obstetrícia. 2006;28(10):575-580
02-07-2006
Summary
Artigos OriginaisQuantitation of amniotic fluid by three- and two-dimensional ultrasonography during the first trimester of pregnancy
Revista Brasileira de Ginecologia e Obstetrícia. 2006;28(10):575-580
02-07-2006DOI 10.1590/S0100-72032006001000002
Views104See morePURPOSE: To determine the values of amniotic fluid in normal fetuses during the first trimester of pregnancy by three- and bi-dimensional ultrasonography. METHODS: In a prospective longitudinal study, 25 normal fetuses were evaluated from the 8th to the 11th week of gestation. Amniotic fluid volume was measured by endovaginal ultrasonography with the three- and two-dimensional modes. The two-dimensional study consisted of volumetric determination by mathematical calculation based on an ellipsoidal shape (constant 0.52) to obtain the amniotic sac and embryo volumes. In the three-dimensional study, the amniotic fluid volume was determined by the VOCAL technique using 6, 9, 15, and 30 degrees of rotation. The amniotic fluid volume obtained by 6-degree rotations was considered to be the final result. In both modes, amniotic fluid volume was obtained by subtracting the volume of the embryo from the volume of the amniotic sac. Data were analyzed statistically for variance (ANOVA), correlation and regression analysis. The level of significance was set at p < 0.05. RESULTS: The amniotic fluid volume as measured by two-dimensional ultrasonography increased from 5.45 to 39.52 cm³ in the range from the 8th to the 11th week (ANOVA - p < 0.05). There was a correlation between gestational age and amniotic fluid volume (p < 0.001, r² = 88.3%). In the three-dimensional study, the amniotic fluid volume increased from 5.7 to 42.9 cm³ in the range from the 8th to the 11th week (ANOVA - p < 0.05), and again a correlation between gestational age and amniotic fluid volume (p < 0.001, r² = 98.1%) was observed. CONCLUSION: an increase in amniotic fluid volume occurs during the first trimester of pregnancy, as determined by the two- and three-dimensional modes. In addition, we have demonstrated that the higher the gestational age, the larger the amniotic fluid volume.
Views104This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Summary
Artigos OriginaisQuantitation of amniotic fluid by three- and two-dimensional ultrasonography during the first trimester of pregnancy
Revista Brasileira de Ginecologia e Obstetrícia. 2006;28(10):575-580
02-07-2006DOI 10.1590/S0100-72032006001000002
Views104See morePURPOSE: To determine the values of amniotic fluid in normal fetuses during the first trimester of pregnancy by three- and bi-dimensional ultrasonography. METHODS: In a prospective longitudinal study, 25 normal fetuses were evaluated from the 8th to the 11th week of gestation. Amniotic fluid volume was measured by endovaginal ultrasonography with the three- and two-dimensional modes. The two-dimensional study consisted of volumetric determination by mathematical calculation based on an ellipsoidal shape (constant 0.52) to obtain the amniotic sac and embryo volumes. In the three-dimensional study, the amniotic fluid volume was determined by the VOCAL technique using 6, 9, 15, and 30 degrees of rotation. The amniotic fluid volume obtained by 6-degree rotations was considered to be the final result. In both modes, amniotic fluid volume was obtained by subtracting the volume of the embryo from the volume of the amniotic sac. Data were analyzed statistically for variance (ANOVA), correlation and regression analysis. The level of significance was set at p < 0.05. RESULTS: The amniotic fluid volume as measured by two-dimensional ultrasonography increased from 5.45 to 39.52 cm³ in the range from the 8th to the 11th week (ANOVA - p < 0.05). There was a correlation between gestational age and amniotic fluid volume (p < 0.001, r² = 88.3%). In the three-dimensional study, the amniotic fluid volume increased from 5.7 to 42.9 cm³ in the range from the 8th to the 11th week (ANOVA - p < 0.05), and again a correlation between gestational age and amniotic fluid volume (p < 0.001, r² = 98.1%) was observed. CONCLUSION: an increase in amniotic fluid volume occurs during the first trimester of pregnancy, as determined by the two- and three-dimensional modes. In addition, we have demonstrated that the higher the gestational age, the larger the amniotic fluid volume.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. -
Artigos Originais
Sonographic determination of fetal gender by measurement of the angles of the genital tubercle
Revista Brasileira de Ginecologia e Obstetrícia. 2005;27(6):310-315
11-11-2005
Summary
Artigos OriginaisSonographic determination of fetal gender by measurement of the angles of the genital tubercle
Revista Brasileira de Ginecologia e Obstetrícia. 2005;27(6):310-315
11-11-2005DOI 10.1590/S0100-72032005000600004
Views44PURPOSE: to evaluate the accuracy of fetal gender prediction at 11 to 13 weeks and 6 days by measuring the anterior and posterior genital tubercle angles. MESTHODS: the anterior and posterior genital tubercle angles were measured in a midsagittal plane in 455 fetuses from 11 to 13 weeks and 6 days. The probability of a correct fetal sex prediction (confirmed after birth) was categorized in accordance with the angle measurements, gestational age and crump-rump length. The optimal accuracy cutoffs were derived from a ROC-plot. The interobserver variability was evaluated by a Bland-Altman plot. RESULTS: the correct fetal sex prediction rate increased with gestational age and crump-rump length. Using a 42-degree anterior angle as a cutoff, a correct fetal sex prediction occurred in 72% of the fetuses from 11 to 11 weeks and 6 days, 86% from 12 to 12 weeks and 6 days and 88% from 13 to 13 weeks and 6 days. Using a 24-degree posterior angle as a cutoff, a correct fetal gender prediction occurred in 70, 87 and 87%, respectively. The interobserver variability evaluation revealed a mean difference between paired measurements of 15.7 and 9 degrees for the posterior and anterior angles, respectively. CONCLUSION: the measurement of the genital tubercle angles showed a high accuracy in correctly predicting the fetal sex from the 12th week of gestation on. However, accuracy was still not high enough for clinical use in pregnancies at risk of serious X-linked diseases.
Key-words PregnancyPregnancy trimester, firstprenatal diagnosisSex determination (analysis)Ultrasonography, prenatalSee moreViews44This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Summary
Artigos OriginaisSonographic determination of fetal gender by measurement of the angles of the genital tubercle
Revista Brasileira de Ginecologia e Obstetrícia. 2005;27(6):310-315
11-11-2005DOI 10.1590/S0100-72032005000600004
Views44PURPOSE: to evaluate the accuracy of fetal gender prediction at 11 to 13 weeks and 6 days by measuring the anterior and posterior genital tubercle angles. MESTHODS: the anterior and posterior genital tubercle angles were measured in a midsagittal plane in 455 fetuses from 11 to 13 weeks and 6 days. The probability of a correct fetal sex prediction (confirmed after birth) was categorized in accordance with the angle measurements, gestational age and crump-rump length. The optimal accuracy cutoffs were derived from a ROC-plot. The interobserver variability was evaluated by a Bland-Altman plot. RESULTS: the correct fetal sex prediction rate increased with gestational age and crump-rump length. Using a 42-degree anterior angle as a cutoff, a correct fetal sex prediction occurred in 72% of the fetuses from 11 to 11 weeks and 6 days, 86% from 12 to 12 weeks and 6 days and 88% from 13 to 13 weeks and 6 days. Using a 24-degree posterior angle as a cutoff, a correct fetal gender prediction occurred in 70, 87 and 87%, respectively. The interobserver variability evaluation revealed a mean difference between paired measurements of 15.7 and 9 degrees for the posterior and anterior angles, respectively. CONCLUSION: the measurement of the genital tubercle angles showed a high accuracy in correctly predicting the fetal sex from the 12th week of gestation on. However, accuracy was still not high enough for clinical use in pregnancies at risk of serious X-linked diseases.
Key-words PregnancyPregnancy trimester, firstprenatal diagnosisSex determination (analysis)Ultrasonography, prenatalSee moreThis is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Pregnancy trimester, first Archives - Revista Brasileira de Ginecologia e Obstetrícia
