The Value Of Three Dimensional Ultrasound And Shear Wave Elastrography In Diagnosis Of Placenta Accreta Spectrum During The Second Trimester

Background With the opening of China’s childbearing policyf,the incidence of placenta accreta spectrum(PAS)will continue to increase.PAS is a serious obstetric disease,which can lead to severe bleeding during delivery and a variety of serious complications after delivery.Ultrasound is the first choice and important examination method for the diagnosis of PAS,but the current examination methods still cannot meet the clinical needs in terms of diagnostic efficiency and evaluation of implantation depth.In this context,this study aims to explore the value of three-dimensional ultrasound combined with shear wave elastography(SWE)in the diagnosis of PAS.Objective To investigate the value of three dimensional ultrasonography and shear wave elastography(SWE)in diagnosis of placenta accreta spectrum during the second trimester,and to discuss the correlation between blood flow parameters,Young’s modulus and implantation degree,so as to provide a basis for the efficient clinical diagnosis of PAS.Methods Sixty pregnant women who underwent prenatal ultrasound examination in middle pregnancy(20-24 weeks)in the department of ultrasound of our hospital were selected as the research objects.Routine,three-dimensional and SWE ultrasonography were performed prenatally.Routine ultrasonography included two-dimensional grey-scale ultrasound and two-dimensional color Doppler ultrasound,and three-dimensional ultrasonography was performed three-dimensional power Doppler ultrasound(3D PDUS).The clinical data and ultrasonic signs were retrospectively analyzed.The blood flow parameters of 3D PDUS were calculated by 4D view software: vascularization index(VI),blood flow index(FI),and vascularization blood flow index(VFI).The tissue hardness of the region of interest was evaluated by SWE,and the diagnostic ability of blood flow parameters and tissue hardness of3 D PDUS was evaluated by ROC curve.According to the clinical or pathological results,the patients were divided into the PAS group and the non-PAS group.The differences in clinical data,ultrasound signs,3D PDUS blood flow parameters and tissue hardness between the two groups were compared.According to the severity,the PAS group was divided into light placental implantation(placenta accreta,PC),heavy placental implantation(s PAS,placenta increta and placenta percreta).The differences of ultrasonic signs,3D PDUS blood flow parameters and tissue hardness between the two groups were compared.Finally,the value of conventional ultrasound and three-dimensional ultrasound combined with shear wave elastography in the diagnosis of PAS during the second trimester was compared,and the ability of each index in the classification and diagnosis of PAS was analyzed.Results According to clinical or pathological results,20 cases were divided into PAS group(6 cases of PC,14 cases of s PAS)and 40 cases of non-PAS group.The age composition between the two groups(>35 years old),gestational times,pregnant bursa position,placenta previa,history of cesarean section,history of intrauterine operation,gestational age of termination of pregnancy,intraoperative blood loss and hysterectomy rate were statistically different(P<0.05).The ultrasonographic findings of PAS group and non-PAS group were significant,including the disappearance of retroplacental space,abundant retroplacental blood flow signal,abnormal intraplacental space,retroplacental myometrium thinning,bladder wall echo interruption,vascular bridge and placental space feeding vessels(P<0.01).The disappearance of the retroplacental space,abnormal intraplacental space,the thinning of the retroplacental myometrium,the interruption of the echo of the bladder wall and the feeding vessels of the placental space are of certain significance for the classification and diagnosis of PAS.The highest diagnostic and typing ability of posterior placental myometrial thinning was achieved,and the diagnostic accuracy was 83.33% and 85.00%,respectively.VI and VFI of PAS group were higher than those of non-PAS group(P<0.01),and when VFI>16.07,the diagnostic ability of PAS was higher than that of VI(AUC: 0.89 vs 0.86).In the diagnosis of PAS classification,VI and VFI showed statistically significant differences between PC and s PAS(P<0.01),and VFI>19.71 has a high ability to diagnose s PAS(Youden index: 0.69 vs0.63);FI had no statistical significance in the diagnosis and classification of PAS(P>0.05).The Emean,Emedian and Emax in PAS group were significantly lower than those in non-PAS group(P<0.01),and when Emean < 8.78 k Pa,Emedian < 9.09 k Pa,the diagnostic ability of PAS was higher than that of Emax(AUC: 0.94,0.94 vs 0.81).In the diagnosis of PAS typing,Emean < 7.15 k Pa,the ability of to diagnose s PAS was higher than Emedian and Emax(Yoden index: 0.69 vs 0.62,0.55).The ability of 3D ultrasound and SWE to diagnose PAS was higher than that of conventional ultrasound(diagnostic accuracy: 85.00%,90.00% vs75.00%).The sensitivity of VFI combined with Emean value in diagnosing PAS was higher than that of conventional ultrasound and single indicator(sensitivity: 90.00% vs 80.00%,85.00%,85.00%).The ability of VFI combined with Emean value to distinguish PC from s PAS was higher than that of single indicator(sensitivity: 100% vs 85.71%,85.71%;diagnostic accuracy: 90.00% vs 85.00%,85.00%).Conclusion The disappearance of retroplacental space,rich retroplacental blood flow signals,abnormal intraplacental lacunae,retroplacental myometrium thinning,bladder wall echo interruption,vascular bridge and the feeding vessels of placental lacunae all have certain significance in the diagnosis of PAS,among which retroplacental myometrium thinning has high diagnostic and classification ability for PAS.The ability of 3D ultrasound and SWE to diagnose PAS was better than that of conventional ultrasound.VFI>16.07,Emean<8.78 k Pa had a high reliability in diagnosing PAS;VFI>19.71,Emean<7.15 k Pa had high diagnostic s PAS ability;The efficacy of 3D ultrasound combined with SWE in the diagnosis and classification of PAS in the middle pregnancy is higher than that of conventional ultrasound and single index,which has certain guiding significance for improving the detection rate of PAS in the middle pregnancy and evaluating the severity.