The application value of measuring fetal head circumference in late pregnancy and predicting intrapartum injury of the levator ani muscle

CUI Yumei; WANG Chunguang; LI Hualin; CHEN Xu

Abstract：Objective To explore the risk factors of transperineal ultrasound tomography(TUI)in diagnosing levator ani muscle injury(LAMI),and to analyze the value of risk factors in predicting levator ani muscle injury during vaginal delivery in primiparous women.Methods 137 primiparous women with a gestational age of over 39 weeks were selected for timely prenatal examination.Intrauterine ultrasound measurements of fetal head circumference,biparietal diameter,and abdominal circumfer-ence were performed within 7 days before delivery.The presence or absence of perineal lateral incision during vaginal delivery and fetal weight during delivery were measured.On the 42nd day after delivery,ultrasound examination was performed on the in-tegrity of the anal levator muscle in postpartum women.According to the results of the transperineal TUI pattern,they were di-vided into four groups:total injury group,complete injury group,partial injury group,and complete group.Using statistical methods,the total injury group,complete injury group,and partial injury group of the levator ani muscle were analyzed and com-pared with the complete group.Statistical differences in age,fetal head circumference,biparietal diameter,abdominal circum-ference,weight,and the presence or absence of perineal lateral incision were analyzed between each two groups,and indepen-dent risk factors for levator ani muscle injury were analyzed.Finally,we compared and analyzed whether there was a statistical difference between the complete injury group and the partial injury group in many influencing factors.Results The fetal head circumference values of the total,complete,and partial injury groups of the levator ani muscle were all higher than those of the intact levator ani muscle group,and all three groups were statistically significant(P<0.05).Multivariate research analysis showed that the size of fetal head circumference was an independent risk factor for levator ani muscle injury;The area under the ROC curve for predicting postpartum anal levator muscle injury in pregnant women was 0.769(95%CI:0.684-0.853),with the optimal cutoff value being the fetal head circumference of 338 mm,sensitivity of 76.0%,and specificity of 84.5%;The perineal lateral resection rate in the total injury group of the levator ani muscle was 50.9%,which was higher than 32.1%in the intact group.The difference between the two groups was statistically significant(P<0.05).Compared with the intact group,the com-plete injury group and partial injury group showed no statistically significant differences in all factors(P>0.05),and multivariate analysis showed that lateral episiotomy was not an independent risk factor for levator ani muscle injury;Conclusion The size of the fetal head circumference during vaginal delivery by primiparous women is related to the occurrence of levator ani muscle in-jury,and is an independent risk factor for levator ani muscle injury;The size of the fetal head circumference during vaginal deliv-ery is not related to the type of injury to the levator ani muscle;Lateral episiotomy is not an independent risk factor for levator ani muscle injury during vaginal delivery in primiparous women.