Exploration On The Clinical Significance Of The Ultrasonographic Measurement In Nuchal Translucency

Objective:To explore the related factors, suitable critical thickness and the clinical significance of nuchal translucency(referred to as NT) by ultrasonographic measurement in fetal NT at the 11-14 weeks of gestation.Methods:Measure fetal crown - rump length(referred to as CRL) by abdominal ultrasound in singleton pregnancies who checked in our hospital from September 1,2007 to August 31,2008 at the 11-14 weeks of gestation, combined last menstrual period to speculate ultrasonic gestation. Then measure nuchal translucency thickness for three times in fetal median sagittal section, and note the maximum observation.Finally, analyze the distribution of normal fetal NT among different maternal age,different fetal sex and different gestation in the cases follow-up,investigate pregnancy outcomes and NT value distribution of abnormal fetuses and explore the suitable critical thickness and the clinical significance of nuchal translucency.Results:There are 121 normal and 16 abnormal fetuses in 143 cases in screening, The normal fetal NT thickness obeys normal distribution, and is increased with gestations. No difference is found among different maternal age or between different fetal sex. It will reach a balance between sensitivity and specificity while the suitable critical NT thickness is 2.5 mm. In 16 cases of abnormal fetuses,12 value is thicker than 2.5 mm,including 2 cases of omphalocele, 1 case of trisomy 18, 1 case of trisomy 21, 3 cases of congenital heart disease, 1 case of cystic hygroma, 3 cases of cystic hygroma mergeing other malformations and 1 case of multiple deformity.Conclusions:The optimum time of ultrasonographic measurement in NT should be at the 11-14 weeks of gestation and CRL should be between 45mm-84mm. NT is increased with gestations. No difference is found among different maternal age or between different fetal sex. It will reach a balance between sensitivity and specificity while NT is 2.5 mm. Therefore we take 2.5 mm as the suitable critical NT thickness.NT possesses an important reference of fetal abnormalities in the first trimester ultrasound examination. Becanse NT is non-invasive and suitable for pregnant women of various ages, it is an effective methods to notice abnormal fetuses as early as possible.