Study On The Ultrasonography In Measurement Fetal Nuchal Fold Thickness And Nuchal Soft Tissue Thickness With Their Applications

Objective:To study the method for ultrasonic measurement the fetal nuchal fold thickness (NFT) and fetal nuchal soft tissue thickness. To establish the reference value of normal NFT and nuchal soft tissue thickness. To utilize high-frequency ultrasound to observe layers of fetal nuchal soft tissue. To analyse value of clinical application of thickened NFT.Methods:Fetal NFT and nuchal soft tissue thickness were prospectively measured in 651 women with accurate menstrual cycle, health, without complications at 15-38 weeks'gestation. There was no umbilical reflex behind the fetal neck. Using Philips IU22 ultrasonic diagnostic equipment with C5-2 transducer and L12-5 transducer. To choose median sagittal section of fetal occipital as the basic measuring plane. As fetal head was flexion or extension, the vertex angle changed, which was consisted by the surface of third cervical vertebra and strong echo of occipital and spinal column. The influence of four imaging angles and ultrasonic frequency for NFT and nuchal soft tissue thickness were compared. All data analyses were conducted with SPSS 16.0 statistic software. Clinical value of thickened NFT was studied.Results:(1)When imaging angle was between 135°～155°, there is no significant difference for NFT and nuchal soft tissue(P>0.05). (2) For NFT of normal fetus, there was significant difference between 5-2MHz and 12-5MHz measurement (P≤0.05). For nuchal soft tissue, there was no significant difference between 5-2MHz and 12-5MHz measurement (P>0.05). (3)High-frequency ultrasound can clearly show the layers of fetal neck structures:normal fetal skin showed a dense layer of low echo, muscle layer was a low and weak echo, which making the measurement was more accurate. Fetal chromosomal abnormalities, fetal edema and fetal obesity were different. (4) In thickened NFT, bad outcome was 66.7%.Conclusions:(1) In median sagittal section of fetal occipital and two angles with normal flexion or slight extension of fetal head can be the standard plane to measure the NFT and fetal nuchal soft tissue. (2)Fetal NFT with high frequency ultrasonography can be accurate. (3)Measurement the NFT in second trimester can obviously enhance the detection rate of chromosomal abnormalities in prenatal diagnosis.Main Innovative Points1. Based on the clinical demand, this study first used imaging angles when measured fetal NFT and nuchal soft tissue. As fetal head was flexion or extension. the vertex angle changed, which was consisted by the surface of third cervical vertebra and strong echo of occipital and spinal column. We compared the NFT and nuchal soft tissue of these four imaging angles to make sure the basic plane and made repeatability test.2. We first used high-frequency ultrasound and low-frequency ultrasound to measure NFT and nuchal soft tissue at the same time and compared them.