The Clinical Significance Of Genetic Ultrasound Markers In Down Syndrome Fetuses And Abnormal Nasal Bone Fetuses

Objective1.To analyze the genetic ultrasound soft markers and other sonographic features in Down syndrome fetuses, then through the evaluation of genetic ultrasound markers to improve the rate of prenatal screening in Down syndrome fetuses.2.To analyze the prognosis of abnormal nasal bone, predict its value for Down syndrome prenatal screening.Study objects and methods1.37fetuses whose karyotypes were diagnosised as Down syndrome by interventional prenatal diagnosis were collected from January2011to December2012in the First People’s Hospital of Yunnan Province. Acording to the rule of control, we chose ultrasound results of the fetuses with normal chromosomesupon Table-Lookingup Methods as control group. All cases were followed up.2. From January2011to December2012, the63fetuses with nasal bone abnormalitieswere collected and followed their pregnancy outcome; Collect the ultrasonic testing of the fetuses that had been diagnosed as Down syndrome during the same period. Meanwhile,6096cases of pregnant women who had a prenatal ultrasonography at the genetic diagnostic center of the First People’s Hospital of Yunnan Province with normal pregnancy and whose baby were normal after delivery were collected and followed-up. Statistical Method:1.The chi-square test of four-fold table or Fisher probabilities test was used in the comparison of sonographic features in Down syndrome and normal fetuses.2. The chi-square test of four-fold table or Fisher probabilities test was used in the comparison of nasal bone abnormality incidence in Down syndrome and normal fetuses. Evaluation Indicator:sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio.Results1. There were7cases Down syndrome fetuses which were low risk in Down syndrome prenatal screening in32casesDown syndrome fetuses. In7cases,2cases were found to have fetal structural abnormalities and all had genetic ultrasound soft markers.In37cases of Down syndrome fetuses,36cases were found with ultrasound anomalies, accounting for97.3%; obvious structural abnormalities in13cases, accounting for35.1%; soft markers anomalies only in23cases.The first two structural malformations were:fetal cardiac malformation9cases (ventricular septal defect4cases, complete endocardial cushion defect2cases), malformation of fetal digestive tract3cases.13cases of structural malformations all with soft marker anomalies and the top two soft markers were:nasal bone absence10cases, long bone short6cases.Only soft marker anomalies in37cases of Down syndrome fetuses were23cases,19patients with two or more soft marker anomalies. The first three soft marker anomalies of all Down syndrome fetuses were:nasal bone dysplasia25cases, NF or NT thickening13cases, ventricular light point11cases.The rate of soft markers anomalies in Down syndrome fetuses was higher than that of structural abnormalities. In Down syndrome fetuses, the only oft markers anomalies was also higher.In control group,8cases were found withultrasound anomalies:ventricular septal defect1cases, ventricular light point4cases; lesions in ventricular system2cases; renal pelvis mild separation lease. All case only had one anomaly. The rest of cases were normal results.Fisher probabilities test was used in the comparison of the rate of sonographic features in Down syndrome and normal fetuses. The differences had statistical significances (P<0.001)。2. There were21cases of fetuses with nasal bone abnormalities in6096cases of pregnant women who were with normal pregnancy when undergone a prenatal ultrasonography and whose babies were normal after delivery, the incidence was0.3%.32cases were found chromosome abnormal in63fetuses with nasal bone abnormalities and the incidence was higher compared with that in normal group (P<0.001).The diagnostic test was made taking this standard as cutoff value, the sensitivity and specificity to predict Down syndrome was67.6%and99.6%respectively, positive predictive value54.4%, negative predictive value99.8%,positive likelihood ratio was225, negative likelihood ratio was0.32.Fetuses with nasal bone abnormalities while normal chromosome31cases, and combined with structural malformations8cases whose prognosis were bad;6cases merged two and more soft markers in the rest of23cases. One fetues was abandoned and one fetues had a small ventricular septal defect in6case. The rest21cases had good prognosis.Conclusions1.The incidence of structural malformation, multiple genetic ultrasound markers anomalies in Down syndrome fetuses is higher than that of normal fetues.2. Fetal abnormal nasal bone is a better ultrasound soft marker to Down syndrome, but it is limited by this marker only.3. Combinative screening involve the pregnant women ages+prenatal serum screening+ultrasound is an effective measure to increase the rate of prenatal screening in Down syndrome fetuses.