Analysis Of The Predictive Value Of Transvaginal Ultrasound Shear Wave Elastography Combined With Cervical Length For Preterm Birth

Objective:Transvaginal ultrasound shear wave elastography was used to evaluate cervical stiffness at 18-24 weeks of gestation and to evaluate the predictive value of preterm birth in combination with cervical length.Methods:A total of 150 pregnant women with single pregnancy at 18-24weeks who underwent prenatal examination in Sichuan Provincial People's Hospital from January 2019 to August 2019 were selected.The cervical length was measured by conventional transvaginal ultrasound firstly,and then SWE technology was started to measure SWE values at four points of the anterior and posterior lips of the cervical orifice.The four points of the cervical were measured respectively to statistically analyze the difference of the cervical orifice elasticity value and its correlation with the gestational age.Pregnancy outcome and neonatal condition were tracked,cervical length and cervical elasticity were compared between the premature delivery group and the full-term delivery group,and risk factors affecting premature delivery were analyzed by univariate analysis and multivariate Logistic regression analysis.Finally,ROC curve was used to analyze the prediction value of cervical length and cervical elasticity respectively and the combination for preterm labor,so as to find the best incisional value.Results:In this study,130 effective cases were finally included,with a median age of 29 years old?26-31?and a median gestational age of 38.3?37.1-40.5?,among which 20 cases?15.4%?were premature delivery and 110 cases?84.6%?were full-term delivery.1.The relationship between cervical morphology and gestational age1.1 Correlation between cervical length and gestational ageAccording to the time of ultrasound examination,the gestational age divided into 18-19⁺⁶ weeks,20-21⁺⁶ weeks,and 22-23⁺⁶ weeks.Cervical length,separately,was 37.0?32.1-41.1?mm,39.0?33.8-41.8?mm,and37.2?33.5-41.5?mm,with no statistical significance?P>0.05?.There was no significant linear relationship between cervical length and gestational age?Spearman correlation coefficient r=-0.08,P>0.05?.1.2 Relationship between cervical elastography parameters and gestational ageOf three groups of different gestational age of pregnant women cervical elasticity on statistical analysis of the results showed:Anterior of External cervical os?AE?,Anterior of internal cervical os?AI?,Posterior of internal cervical os?PI?,and Posterior of External cervical os?PE?.By statistical analysis,there was a linear relationship between cervical elasticity and gestational age.The regression equation can be obtained respectively for Y_AE=-0.59X+21.76,Y_AI=-1.51X+50.69,Y_PI=-2.19X+70.92 and Y_PE=-0.50X+19.39?P<0.05?.The overall distribution of cervical elasticity in different cervical sites was not the same??2=246.37,P<0.05?.The results showed that the elasticity of the posterior of internal cervical os was higher than anterior of internal cervical os?P<0.01?.The elasticity of the internal cervical os was higher than the external cervical os?P<0.01?.There was no significant difference in the elasticity of the external cervical os?P>0.05?.1.Analysis of risk factors affecting premature birthIn this study,there were 20 cases of premature delivery and 110 cases of full-term delivery.Univariate analysis of related indicators showed that the risk factors of preterm birth were previous history of spontaneous abortion,history of preterm birth,elasticity value of internal cervical os,elasticity value of anterior external cervical os and cervical length.The binary Logistic regression analysis found that PI?25 th and CL?25 mm was the high risk factors of preterm birth.Further analysis found that Logit?P?(obtained by PI?25 ^th+CL?25 mm)was the strongest risk factor for premature?OR=25.13,P<0.05?.3.Value analysis of prediction and diagnosis of premature birth with different ultrasonic indicators of cervical morphologyThe results showed that when CL<25mm,the incidence of premature birth was 71.4%.When CL was 25-35mm,the incidence of preterm birth was 26.2%.When CL>was 35mm,the incidence of preterm labor was 4.9%,indicating that the shorter the cervical length,the greater the likelihood of preterm labor.When the SWE<25 ^th,the incidence of premature birth was 34.4%;When SWE was the 25-75^th,the incidence of premature birth was 10.6%.When SWE>75^th,the incidence of preterm labor was 6.2%,indicating that the softer the cervix,the greater the likelihood of preterm labor.The results showed that the area under the ROC curve?AUC=0.92?for preterm delivery predicted by cervical length combined with cervical elasticity value was higher than that predicted by cervical length and cervical elasticity value alone.At the same time,the joint prediction model L=1*PI+1.32*CL was obtained,and L?60.24had the highest predictive value for preterm labor,with a sensitivity of 90.0%and specificity of 90.0%.Conclusion:In this study,the cervical length at 18-24 weeks of gestation and the elasticity values of different parts of the cervix were measured and the following conclusions were obtained:?1?in the second trimester,the length of the cervix did not change significantly as the gestation week increased,and the length of the cervix remained relatively stable in the second trimester.?2?the hardness of different parts of the cervix was different.With the development of pregnancy,the cervix gradually becomes soft.?3?short cervix and soft cervix were risk factors for premature birth,and the risk of both of them occurring simultaneously was significantly increased.?4?cervical length combined with cervical elasticity could improve the prediction efficiency of preterm labor.