Trisomy 21 Archives - Revista Brasileira de Ginecologia e Obstetrícia
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2018;40(7):384-389
The main objective of this study was to examine the diagnostic performance of the first-trimester combined test for aneuploidies in unselected pregnancies from Rio de Janeiro and compare it with the examples available in the literature.
We investigated 3,639 patients submitted to aneuploidy screening from February 2009 to September 2015. The examination is composed of the Fetal Medicine Foundation risk evaluation based on nuchal translucency evaluation, mother’s age, presence of risk factors, presence of the nasal bone and Doppler of the ductus venous in addition to biochemical analysis of pregnancy-associated plasma protein A (PAPP-A) and beta-human chorionic gonadotropin (β-hCG) markers. The cut-off point for high risk for aneuploidies was defined as greater than 1:100, with intermediate risk defined between 1:100 and 1:1,000, and low risk defined as less than 1:1,000. The variable aneuploidy was considered as a result not only of trisomy of chromosome 21 but also trisomy of chromosomes 13 and 18.
Excluding the losses, the results of 2,748 patients were analyzed. The firsttrimester combined test achieved 71.4% sensitivity with a 7.4% false-positive (FP) rate, specificity of 92.6%, positive predictive value (PPV) of 6.91% and negative predictive value (NPV) of 99.76%, when the cut-off point considered was greater than 1:1,000. Through a receiving operating characteristics (ROC) curve, the cut-off point that maximized the sensitivity and specificity for the diagnosis of aneuploidies was defined as 1:1,860. When we adjusted the false-positive (FP) rate to 5%, the detection rate for this analysis is 72.7%, with a cut-off point of 1:610.
The combined test of aneuploidy screening showed a detection rate inferior to those described in the literature for a higher FP rate.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2018;40(7):384-389
The main objective of this study was to examine the diagnostic performance of the first-trimester combined test for aneuploidies in unselected pregnancies from Rio de Janeiro and compare it with the examples available in the literature.
We investigated 3,639 patients submitted to aneuploidy screening from February 2009 to September 2015. The examination is composed of the Fetal Medicine Foundation risk evaluation based on nuchal translucency evaluation, mother’s age, presence of risk factors, presence of the nasal bone and Doppler of the ductus venous in addition to biochemical analysis of pregnancy-associated plasma protein A (PAPP-A) and beta-human chorionic gonadotropin (β-hCG) markers. The cut-off point for high risk for aneuploidies was defined as greater than 1:100, with intermediate risk defined between 1:100 and 1:1,000, and low risk defined as less than 1:1,000. The variable aneuploidy was considered as a result not only of trisomy of chromosome 21 but also trisomy of chromosomes 13 and 18.
Excluding the losses, the results of 2,748 patients were analyzed. The firsttrimester combined test achieved 71.4% sensitivity with a 7.4% false-positive (FP) rate, specificity of 92.6%, positive predictive value (PPV) of 6.91% and negative predictive value (NPV) of 99.76%, when the cut-off point considered was greater than 1:1,000. Through a receiving operating characteristics (ROC) curve, the cut-off point that maximized the sensitivity and specificity for the diagnosis of aneuploidies was defined as 1:1,860. When we adjusted the false-positive (FP) rate to 5%, the detection rate for this analysis is 72.7%, with a cut-off point of 1:610.
The combined test of aneuploidy screening showed a detection rate inferior to those described in the literature for a higher FP rate.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2002;24(9):601-608
DOI 10.1590/S0100-72032002000900006
Purpose: to appraise the value of ultrasonographic parameters for the diagnosis of fetal Down syndrome (T21), in order to permit its use in routine clinical practice. Methods: this is a prospective cohort study using various ultrasonographic parameters for the prediction of T21. A total of 1662 scans were evaluated in the cohort study and 289 examinations were analyzed as a differential sample to test the normality curve from October 1993 to November 2000. The statistical analysis was based on the calculation of intra- and interobserver variations, the construction of normality curves for the studied parameters, as well as their validity tests, and the calculation of sensitivity, specificity, relative risk, likelyhood ratio and posttest predictive values. Results: among 1662 cases, 22 fetuses (1.32%) with T21 were identified. The normality curves were built for nucal fold thickness, femur/foot ratio and nasal bone length. Renal pelvis had a semiquantitative distribution and the proposed cutoff level was 4.0 mm. Sensitivity, specificity, false positive rate, relative risk and likelyhood ratio for nucal fold measurements above the 95th percentile were 54.5%, 95.2%, 4.9%, 20.2 and 11, respectively. For nasal bone measurements below the 5th percentile, 59.0%, 90.1%, 9.0%, 13.4 and 6.5. For femur/foot ratio below the 5th percentile, 45.5%, 84.4%, 15.6%, 3.7 and 2,6. For renal pelvis greater than 4.0 mm, 36.4%, 89.2%, 10.9%, 4.5 and 3.4. For absent fifth finger middle phalanx, 22.7%, 98.1%, 1.9%, 13.2 and 11.9. For the presence of major malformations, 31.8%, 98.7%, 1.3%, 27.2 and 24,8. After calculating the probability rates and the incidence of T21 in different maternal ages, a table for posttest risk using ultrasonographic parameters was set up. Conclusions: normality curves and indices for the assessment of risk for fetal Down syndrome on a population basis were established by the utilization of different maternal ages and by multiplying factors proposed by the authors. It was not possible to establish a normality curve for renal pelvis measurements, because of their semiquantitative distribution.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2002;24(9):601-608
DOI 10.1590/S0100-72032002000900006
Purpose: to appraise the value of ultrasonographic parameters for the diagnosis of fetal Down syndrome (T21), in order to permit its use in routine clinical practice. Methods: this is a prospective cohort study using various ultrasonographic parameters for the prediction of T21. A total of 1662 scans were evaluated in the cohort study and 289 examinations were analyzed as a differential sample to test the normality curve from October 1993 to November 2000. The statistical analysis was based on the calculation of intra- and interobserver variations, the construction of normality curves for the studied parameters, as well as their validity tests, and the calculation of sensitivity, specificity, relative risk, likelyhood ratio and posttest predictive values. Results: among 1662 cases, 22 fetuses (1.32%) with T21 were identified. The normality curves were built for nucal fold thickness, femur/foot ratio and nasal bone length. Renal pelvis had a semiquantitative distribution and the proposed cutoff level was 4.0 mm. Sensitivity, specificity, false positive rate, relative risk and likelyhood ratio for nucal fold measurements above the 95th percentile were 54.5%, 95.2%, 4.9%, 20.2 and 11, respectively. For nasal bone measurements below the 5th percentile, 59.0%, 90.1%, 9.0%, 13.4 and 6.5. For femur/foot ratio below the 5th percentile, 45.5%, 84.4%, 15.6%, 3.7 and 2,6. For renal pelvis greater than 4.0 mm, 36.4%, 89.2%, 10.9%, 4.5 and 3.4. For absent fifth finger middle phalanx, 22.7%, 98.1%, 1.9%, 13.2 and 11.9. For the presence of major malformations, 31.8%, 98.7%, 1.3%, 27.2 and 24,8. After calculating the probability rates and the incidence of T21 in different maternal ages, a table for posttest risk using ultrasonographic parameters was set up. Conclusions: normality curves and indices for the assessment of risk for fetal Down syndrome on a population basis were established by the utilization of different maternal ages and by multiplying factors proposed by the authors. It was not possible to establish a normality curve for renal pelvis measurements, because of their semiquantitative distribution.