ABSTRACT
Objective To evaluate the value of nuchal translucency (NT) thickness in the fetal chromosome abnormality screening. Methods 11 086 pregnant women received NT measurement in 11 ~ 13+6 weeks at Hainan general hospital from January 2010 to December 2014 were selected in the study. The NT thickness was measured according to guidelines from Fetal Medicine Foundation. 122 fetuses (NT≥2.5 mm) were recruited to accept karyotype analysis. Results 11 086 pregnant women received NT measurement in 11 ~13+6 weeks, in which 122 cases′ NT are more than or equal to 2.5 mm, with a positive rate of 1.10%. 122 cases of fetal NT thickening are between 2.5 to 12.0 mm, with the average degree at (4.5 ± 2.1)mm. 122 invasive prenatal diagnostic specimens chromosome karyotype analysis results showed chromosomal abnormalities in 21 cases (abnormal rate of 17.2%), the abnormal chromosome number in 17 cases and abnormal structure in 4 cases. The top 3 are trisomy 21 (12 cases, 57.1%), chromosome pericentric inversion (3 cases, 14.3%), and trisomy 18 (2 cases, 9.5%). Fetal chromosomal abnormalities resulting from different childbirth age, the sex of the fetus, NT thickness showed significant statistical difference (P < 0.05). The concrete manifestation is that fetal chromosomal anomaly detection rate in childbirth by women more than 35 years old age are higher than other age. Female fetal chromosomal anomaly detection rate is higher than the male , and NT thickness of 5mm of fetal chromosomal abnormality rate is significantly higher than the thickness of NT group at 2.5mm~ and 3.5mm~. Fetal NT thickening of NT measurements was in significant positive correlation with fetal chromosome abnormal rate (χ2=15.533, P < 0.001). Logistic regression analysis found that with a higher NT thickness , risk of fetal chromosomal abnormalities would be significantly higher , and thickening of NT could be an independent predictor of fetal chromosome abnormalities. Conclusion In early pregnancy, ultrasound examination of fetal ultrasound screening of NT thickness can be used as an important index of fetal chromosomal abnormality , and interventional diagnosis of prenatal NT thickness increase could pose increased risk of fetal chromosomal abnormalities.
ABSTRACT
Objective To retrospectively assess the diagnostic value of nuchal translucency (NT) thickness and facial profile ultrasonic markers [including frontomaxillary facial (FMF) angle,and the ratio of prenasal thickness to nasal bone length (PT/NBL)] for trisomy 21 syndrome in first-trimester fetuses.Methods Ultrasonograhic images of 35 fetuses with trisomy 21 syndrome and 70 gestational age matched normal fetuses were analyzed in first-trimester.NT,FMF angle and the PT/NBL ratio were measured retrospectively in stored images from digital database between January 2012 and December 2015.The diagnostic value of NT,FMF angle and PT/NBL ratio were compared with different combinations.Results (1) The mean NT was significantly higher in the trisomy 21 group than that in controls (t =7.401,P =0.00).The NT above 2.5mm was observed in 20 trisomy 21 fetuses (57.1％) and in 3 normal fetuses (4.3％).(2) The mean FMF angle was significantly higher in the trisomy 21 group than that in controls (t =-5.283,P =0.00).The FMF angle above the 95th percentile (93.6°) was observed in 13 trisomy 21 fetuses (37.1％) and in 1 normal fetus (1.4％).(3) The mean PT/NBL ratio was significantly higher in the trisomy 21 group than that in controls (t =-7.826,P =0.00).The PT/NBL ratio above the 95th percentile (0.93) was observed in 19 trisomy 21 fetuses (54.3％) and in 4 normal fetuses (5.7％).(4) The sensitivity and Youden index for trisomy 21 increased gradually,which were 57.1 ％ and 0.528 by using NT,and 74.3％ and 0.686 by using NT and FMF angle,and 91.4％ and 0.828 by using NT,FMF angle and PT/NBL ratio.There were significant differences in the detection rates of trisomy 21 among the three strategies,while the diagnostic specificity of the three strategies were more than 90％.Conclusions The three parameters are significantly increased in trisomy 21 fetus in first-trimester.First,increased NT was most commonly detected,followed by increased PT/NBL ratio,and increased FMF angle again.Detection rates for trisomy 21 fetuses in first-trimester by ultrasound screening can be significantly improved if combination of all three parameters rather than just one parameter are performed.