| Objective:To analyze the changes of fetal nasal bone length in the first and second trimester of pregnancy with gestational age,summarize the ultrasound findings of the fetuses with abnormal nasal bone,and evaluate the application value of abnormal nasal bone in chromosomal abnormality screening.Materials and methods:A total of 1349 pregnant women from Wuxi Maternal and Child Health Hospital were selected during the period from January 2016 to December 2017 as the normal group.The menstrual cycle of pregnant women was clear,all were singletons,the gestational age was 11-25 weeks,and the growth lines of the fetus coincided with the gestational age,no abnormalities were detected by ultrasonic examination,postpartum follow-up newborn physical examination is normal.The median sagittal section of the fetal head was scanned,the length of the nasal bone was measured,then grouped according to the gestational age.During the same period,a total of 93 fetuses with abnormal nasal bone were examined in the first and second trimester of pregnancy fetal ultrasound screening,and amniocentesis were selected as the case group,karyotype results were followed up,the situations of abnormal nasal bone combined with other ultrasound soft markers(the first trimester of pregnancy included thickened nuchal translucency,tricuspid regurgitation,reversed the ductus venosus a-wave,the second trimester of pregnancy included thickened nuchal fold,mild ventriculomegaly,choroid plexus cyst,shortened femur or humerus,mild hydronephrosis,hypoplasia of the middle phalanx of the fifth finger and clinodactyly,echogenic bowel,intracardiac echogenic focus,increased ilium wing angle)and/or structural abnormalities(included the brain,spine,heart,chest and abdomen,limbs,face)and the incidence of chromosomal abnormalities were analyzed.Results:1.The length of the nasal bone of the normal group increased with the increase of gestational age at 11-25 weeks of pregnancy,the length of the nasal bone was positively correlated with the gestational age,the correlation coefficient r was 0.905(P<0.001),the length of the fetal nasal bone was the dependent variable Y,and the gestational age was the independent variable X,the linear regression equation Y=0.042X-0.248.2.The other ultrasound soft markers and/or structural abnormalities of fetuses in case group:①Among 58 cases with absence of nasal bone,37 cases were combined with other soft markers and/or structural abnormalities(37/58,63.79%),② Among 35 cases with hypoplasia of nasal bone,23 cases were combined with other soft markers and/or structural abnormalities(23/35,65.71%).There was no significant differences in combined with other soft markers and/or structural abnormalities between the two different types of abnormal nasal bone(P>0.05).3.The results of chromosome karyotype in case group were as follows:① 64 cases with normal chromosome(64/93,68.82%),② 29 cases with abnormal chromosome(29/93,31.18%),including 22 cases with trisomy 21,3 cases with trisomy 18,1 case with trisomy 13 and 3 cases with other chromosome abnormalities.4.Different types of abnormal nasal bone were compared:① In the cases with absence of nasal bone,of which 40 cases were normal chromosome(40/58,68.97%)and 18 cases were abnormal chromosome(18/58,31.03%),②In the cases with hypoplasia of nasal bone,of which 24 cases were normal chromosome(24/35,68.57%)and 11 cases were abnormal chromosome(11/35,31.43%).There was no significant difference in the incidence of chromosomal abnormalities between the two different types of abnormal nasal bone(P>0.05).5.Compared according to the isolation and non-isolation(referring to simultaneous combined with other soft markers andjor structural abnormalities)abnormal nasal bone:①33 cases with isolated abnormal nasal bone had 30 fetuses with normal chromosomes(30/33,90.91%)and 3 fetuses with abnormal chromosomes(3/33,9.09%),②60 cases with non-isolated abnormal nasal bone had 34 fetuses with normal chromosomes(34/60,56.67%)and 26 fetuses with abnormal chromosomes(26/60,43.33%).The incidence of chromosomal abnormalities in non-isolated abnormal nasal bone was significantly higher than that in isolated abnormal nasal bone(P<0.05).Conclusions:1.The length of the fetal nasal bone increased with the increase of gestational age at 11-25 weeks of pregnancy,and the nasal bone length was positively correlated with the gestational age.2.Abnormal fetal nasal bone could be used as an important ultrasound marker for the evaluation of chromosomal abnormalities,especially for the trisomy 21.3.There were no significant differences in combined with other soft markers and/or structural abnormalities and the incidence of chromosomal abnormalities between different types of abnormal nasal bone.4.The incidence of fetal chromosomal abnormalities in non-isolated abnormal nasal bone was significantly higher than that in isolated abnormal nasal bone.When ultrasonic examination revealed abnormal nasal bone,it should be carefully examined for other ultrasound soft markers and structural abnormalities. |
