The Study Of The Influence Of The Time Interval From The Last Ultrasound To The Delivery Time And The Theickness Of Fetal Soft Tissue On The Estimation Of Fetal Weight

Objective: Objective to study the effect of the time interval of the last ultrasound to the delivery time and the thickness of fetal soft tissue on the estimation of fetal weight.Methods: Choose 272 cases of pregnant women of intrauterine single live births who take production inspection timely and delivery in the hospital from June 2016 to January 2017.The ultrasonic measurement of fetal biparietal diameter,head circumference,abdominal circumference,femur length,anterior abdominal wall thickness of soft tissue and femoral subcutaneous soft tissue thickness,the HadlockI formula was used to estimate fetal weight,and track their birth weight.At the time of ultrasound was 37 ~ 41 weeks of gestation,calculation of ultrasound to the delivery time interval,time interval will be selected according to the fetus were divided into four groups(group A: 0 ~ 3days,86 cases;group B: 4 ~ 7 days,70 cases;group C: 8 ~ 14 days,64 cases;group D: 15 ~ 21 days,52 cases).Results : There were significant differences in the absolute error and relative error of the four groups of fetal weight estimation(P < 0.05).Combined with the absolute error of the number of point estimates,the four groups of fetal weight estimation of the absolute error of the comparison of the number of groups: group B group C group D group,the relative error of the rate of comparison: B group A group C group D group.Were moderate positive correlation exists at the time of the absolute error of ultrasonic inspection to delivery time interval and the estimation of fetal weight,not closely related to the degree of fetal anterior abdominal wall soft tissue thickness,fetal femoral subcutaneous soft tissue thickness and the absolute error of the estimation of fetal weight.There was a significant difference in the thickness of soft tissue thickness of anterior abdominal wall and the thickness of soft tissue between the fetus in the macrosomia group and the normal weight infant group(P < 0.05).The HadlockI formula of fetal weight estimation results than 4000 g prediction of macrosomia sensitivity 69.23%,specificity 98.78%,positive predictive value of 85.71%,negative predictive value 98.78%;sensitivity of 73.07% fetal anterior abdominal wall soft tissue thickness of 10 mm prediction of macrosomia,specificity 97.96%,positive predictive value of 79.16%,negative predictive value 97.96%;sensitivity of 57.69% fetal thigh subcutaneous the soft tissue thickness of 20 mm prediction of macrosomia,specificity of 97.15%,positive predictive value 68.18%,and negative predictive value of 97.15%.The diagnostic value of ultrasound formula for predicting macrosomia is high,and the accuracy of predicting fetal macrosomia is higher than that of single index,which is based on the combination of two indexes of anterior abdominal soft tissue and the thickness of soft tissue.Conclusion: It is more accurate that the full-term fetus make ultrasound estimation of fetal weight before delivery 4 ~ 7 days.The fetal ultrasound examination to the delivery interval affect absolute error of estimation of fetal weight,there are moderate positive correlation between the two.The macrosomia and normal birth weight fetal anterior soft tissue the abdominal wall thickness,fetal femur soft tissue thickness are different.Diagnostic value of the ultrasound estimation of fetal weight prediction of macrosomia is high,and combination of the thickness of the soft tissue of fetal combined,diagnostic accuracy of prenatal prediction of macrosomia may further improve.