prenatal diagnosis Archives - Page 4 of 6 - Revista Brasileira de Ginecologia e Obstetrícia
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.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2002;24(3):167-173
DOI 10.1590/S0100-72032002000300004
Purpose: to study the value of nuchal translucency (NT) measurement in the screening for chromosomal abnormalities at 10-14 weeks of gestation. Methods: a total of 1152 fetuses were studied consecutively. In 124 cases a cytogenetic study was performed on material obtained from a biopsy of the chorionic villus, and in 1028 cases the result was based on the postnatal phenotype. In addition to the routine ultrasonographic examination, all fetuses were submitted to measurement of the NT thickness. For statistical analysis Student's t test and ANOVA were used. Sensitivity, specificity, positive and negative predictive values, false-positive rate and likelihood ratio were calculated. Results: twenty-three cases of chromosomal abnormalities occurred. Of these abnormal cases, NT measurement was above the 95th percentile in 16 (sensitivity of 69.5%). In the group of normal fetuses (1129 cases), NT measurement was above the 95th percentile in 41 (specificity of 96.3%, positive and negative predictive values of 28.0% and 99.3%, respectively, false-positive rate of 3.7% and likelihood ratio of 19.1). Conclusion: our results suggest that the presence of chromosomal abnormalities may be strongly suspected when there is an increased NT thickness. One can infer that the quantitative NT analysis is sufficient to classify the risk of chromosomal anomalies in the first trimester of the pregnancy. Although the ultrasound operator's training and skill is still necessary, it is a method of clinical applicability.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2002;24(3):167-173
DOI 10.1590/S0100-72032002000300004
Purpose: to study the value of nuchal translucency (NT) measurement in the screening for chromosomal abnormalities at 10-14 weeks of gestation. Methods: a total of 1152 fetuses were studied consecutively. In 124 cases a cytogenetic study was performed on material obtained from a biopsy of the chorionic villus, and in 1028 cases the result was based on the postnatal phenotype. In addition to the routine ultrasonographic examination, all fetuses were submitted to measurement of the NT thickness. For statistical analysis Student's t test and ANOVA were used. Sensitivity, specificity, positive and negative predictive values, false-positive rate and likelihood ratio were calculated. Results: twenty-three cases of chromosomal abnormalities occurred. Of these abnormal cases, NT measurement was above the 95th percentile in 16 (sensitivity of 69.5%). In the group of normal fetuses (1129 cases), NT measurement was above the 95th percentile in 41 (specificity of 96.3%, positive and negative predictive values of 28.0% and 99.3%, respectively, false-positive rate of 3.7% and likelihood ratio of 19.1). Conclusion: our results suggest that the presence of chromosomal abnormalities may be strongly suspected when there is an increased NT thickness. One can infer that the quantitative NT analysis is sufficient to classify the risk of chromosomal anomalies in the first trimester of the pregnancy. Although the ultrasound operator's training and skill is still necessary, it is a method of clinical applicability.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2002;24(2):121-127
DOI 10.1590/S0100-72032002000200008
Purpose: to estimate the performance of ultrasound to detect gestations at risk for fetal chromosomal abnormalities. Methods: four hundred and thirty-six patients selected for the study had undergone ultrasound examination and fetal karyotyping, between March 1993 and March 1998. Two hundred and seventy-seven patients had fetal karyotype for fetal malformation detected on ultrasound and 158 for parental anxiety with normal ultrasound examination. Ultrasound sensitivity and specificity were calculated using fetal karyotype as gold standard. The relative risk for each chromosomal abnormality was calculated according to the altered system on ultrasound examination and the risks of the presence of one or more abnormalities on ultrasound, using the Epi-Info 6.0 software package for statistical analysis. Results: the relative risks for chromosomal abnormalities were 89 for face malformations, 53 for abdominal wall and cardiovascular, 49.6 for neck, 44.6 for extremities, 42.4 for lung, 32.7 for gastrointestinal tract, 27.4 for central nervous system and 23.0 for urinary tract malformations. The relative risk for fetal chromosomal anomalies for genital, thorax, spine and muscle and/or skeletal malformations was not appropriate for calculation because they occurred at very low frequencies. An isolated malformation detected by ultrasound is associated with a 7.8 times higher relative risk for chromosomal anomalies than none, and associated morphologic malformations have a 33.8 times higher relative risk for chromosomal abnormalities. Conclusion: ultrasound has good performance to detect gestations at risk for chromosomal abnormalities.
Summary
Revista Brasileira de Ginecologia e Obstetrícia. 2002;24(2):121-127
DOI 10.1590/S0100-72032002000200008
Purpose: to estimate the performance of ultrasound to detect gestations at risk for fetal chromosomal abnormalities. Methods: four hundred and thirty-six patients selected for the study had undergone ultrasound examination and fetal karyotyping, between March 1993 and March 1998. Two hundred and seventy-seven patients had fetal karyotype for fetal malformation detected on ultrasound and 158 for parental anxiety with normal ultrasound examination. Ultrasound sensitivity and specificity were calculated using fetal karyotype as gold standard. The relative risk for each chromosomal abnormality was calculated according to the altered system on ultrasound examination and the risks of the presence of one or more abnormalities on ultrasound, using the Epi-Info 6.0 software package for statistical analysis. Results: the relative risks for chromosomal abnormalities were 89 for face malformations, 53 for abdominal wall and cardiovascular, 49.6 for neck, 44.6 for extremities, 42.4 for lung, 32.7 for gastrointestinal tract, 27.4 for central nervous system and 23.0 for urinary tract malformations. The relative risk for fetal chromosomal anomalies for genital, thorax, spine and muscle and/or skeletal malformations was not appropriate for calculation because they occurred at very low frequencies. An isolated malformation detected by ultrasound is associated with a 7.8 times higher relative risk for chromosomal anomalies than none, and associated morphologic malformations have a 33.8 times higher relative risk for chromosomal abnormalities. Conclusion: ultrasound has good performance to detect gestations at risk for chromosomal abnormalities.