الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
 |  | from | 126 |  |  |
| | | from | 126 | | |
Abstract
Early prenatal diagnosis of fetal sex is necessary to optimize pregnancy management in families known to be at risk of some heritable disorders. Two alternative non-invasive techniques for first trimester sex determination have recently been described: 3D ultrasound can be an effective and fast way of identifying fetal gender in the first trimester; the advantages of 3D ultrasound stem from its ability to virtually reproduce all required views. Moreover, real-time PCR of the SRY gene promises to be a reliable technique for early fetal sexing in maternal plasma; the presence of Y-chromosome sequences in maternal blood plasma indicates that the fetus is male, whereas lack of a signal will indicate that the fetus is female. Both methods provide a reliable option of avoiding invasive testing in female pregnancies.
A total of 50 pregnant females with history of X-linked conditions were offered first trimester non-invasive fetal gender determination at 11–13 weeks gestation by sacral region volume acquisition 3D ultrasound and analysis of free fetal DNA (ffDNA) in maternal plasma. Fetal sex were confirmed after birth in all the cases; analyses of phenotype at birth revealed that among 50women enrolled in this study, 32 (64.0%) gave birth to male fetuses and the remaining 18 (36.0%) patients were female fetuses. There were no obvious external genital abnormalities recorded at birth in any of the cases.
After studying the 3D volumes we recorded a diagnosis of male or female in all cases. from these 50 cases correct prediction of fetal gender by volume ultrasound was achieved in 47 cases (94.0%). The mean genital angle in males was significantly higher compared with that in females. The ROC curve revealed that the genital angle measurements have a high degree of accuracy in fetal gender determination; an angle of ≥ 29◦ was identified as the best cut-off for male gender determination. All fetuses subsequently confirmed as males had an angle above this cut-off, except one whose angle was equal to its upper limit (29◦); all female fetuses had an angle below the cut-off, except two who had an angle of 29◦ at 11-13 weeks, yielding a sensitivity of 97% and a specificity of 89.0%. Genital angle measurements were not correlated with maternal body mass index, gestational age, or the fetal crown rump length.
DNA extraction protocol had an optimal performance as demonstrated by the presence of GLO, detected in all samples examined. By using the SRY assays we observed a concordance of 92% (46/50) with regard to fetal gender determination. The SRY assay detected male fetuses in 30 out of 32 samples from pregnant women carrying male fetuses, showing sensitivity for SRY assay of (93.8%). Moreover, by using the SRY assay, we correctly detected 16 out of 18 samples from pregnant women carrying female fetuses showing a specificity of fetal gender detection of 88.9%.
A good degree of agreement was calculated between ultrasound and the molecular technique. By using both techniques we observed a concordance in 49 out of the 50 studied cases with regard to fetal gender determination with a total accuracy of (98%). The combined markers detected 31 out of 32 pregnant women carrying male fetuses, showing a sensitivity of (96.8 %). Moreover, we correctly detected 18 out of 18 samples from pregnant women carrying female fetuses showing a specificity of fetal gender detection of 100%.
Finally, the effect of gestation on each method of assessment was assessed; this study demonstrated that the gestational age of the fetus has a material effect on the accuracy rate of gender determination. The ability to assign fetal gender confidently using ultrasonography and the combined technique significantly improved with increasing gestational age from 11 to 13 weeks (p< 0.05). On the other hand, gestational age did not affect the accuracy of gender identification by using the cffDNA assay.