Static And Dynamic MRI Study Of Stress Urinary Incontinence After Vaginal Delivery

Objective To comprehensively evaluate the pelvic floor morphology and function of primiparas with stress urinary incontinence(SUI)after vaginal delivery,and to explore the correlation between pelvic floor indicators and the occurrence and severity of postpartum SUI using static and dynamic MRI.Materials and methods Primiparas after vaginal delivery were prospectively collected in the obstetrics department of Tianjin First Central Hospital from October2016 to September 2018,clinical SUI assessment,international consultation on incontinence questionnaire-short form(ICIQ-SF)and pelvic floor MRI were performed at 6 weeks postpartum,which were divided into 64 cases of incontinence group and 92 cases of normal group.Pelvic floor MRI examination included static and dynamic scanning;static MRI adopts the FSE sequence;dynamic MRI adopts the B-FFE sequence;strain state adopts the SSFSE sequence,and axial and sagittal scanning were performed.On static and dynamic MRI images,pelvic floor indicators were measured by two radiologists under rest and strain state,including puborectalis thickness(PRT),levator ani hiatus area(LHA),H-line,M-line,distance from bladder neck to pubococcygeal line(B-PCL),distance from cervix to pubococcygeal line(U-PCL),levator ani plate angle(LPA),anterior angle of urethra(AUA),retrovesical ang1e(RVA),bladder neck descent(BND),functional urethral length(FUL)and presence or absence of bladder neck funnel.The consistency of pelvic floor indicators measured between two physicians were evaluated by intraclass correlation coefficient(ICC).Univariate analysis(independent sample t test and chi-square test)and multivariate logistic regression analysis were used to screen pelvic floor indicators closely related to postpartum SUI.Receiver operating characteristic(ROC)curve analysis was performed to evaluate the predictive value of the pelvic floor indicators selected from multivariate analysis for postpartum SUI,and the area under the ROC curve(AUC),optimal threshold,sensitivity and specificity were calculated.Correlation between pelvic floor indicators related to postpartum SUI and ICIQ-SF scores were performed by Spearman correlation test.Results Two physicians showed good consistency in the measurement of pelvic floor indicators of the subjects(ICC 0.796～0.949).Univariate analysis showed that the postpartum incontinence group compared with the normal group,LHA,B-PCL,BND,AUA and RVA increased[(25.51±6.28)cm~2 vs(16.58±2.79)cm~2,(-1.08±0.94)cm vs(0.11±0.64)cm,(2.25±1.07)cm vs(1.20±0.76)cm,(68.62±13.47)°vs(38.69±19.09)°,(156.67±9.03)°vs(143.41±9.42)°],FUL decreased[(1.86±0.34)cm vs(2.36±0.29)cm],bladder neck funnel ratio increased[87.5%(56/64)vs29.3%(27/92)]under strain state(all P<0.05).The above indicators were included in the multivariate logistic regression analysis,and it was found that LHA,RVA,FUL and bladder neck funnel under strain state were closely related to postpartum SUI(P<0.05),with OR values of 10.513,5.222,0.404 and 10.191.ROC analysis showed that the AUC of LHA for predicting postpartum SUI was 0.907,threshold was18.68cm~2,sensitivity and specificity were 89.1% and 82.6%;the AUC of RVA was0.841,threshold was 151.58°,sensitivity and specificity were 75%and 83.7%;the AUC of FUL was 0.879,threshold was 2.075cm,sensitivity and specificity were76.6%and 89.1%;the AUC of bladder neck funnel was 0.791,sensitivity and specificity were 87.5% and 70.7%;the AUC of four indicators was 0.970,sensitivity and specificity were 92.2% and 96.7%.ICIQ-SF scores was highly linearly correlated with RVA(r=0.929,P<0.05) and low linearly correlated with bladder neck funnel(r=0.306,P<0.05),while LHA and FUL were not correlated with ICIQ-SF scores(P>0.05).Conclusions 1.Static and dynamic MRI can evaluate the morphological and functional abnormalities of the urethral support system and the urethral sphincter system of primiparas with SUI after vaginal delivery;2.LHA,FUL,RVA and bladder neck funnel formation under strain state are the pelvic floor indicators closely related to postpartum SUI,and the last two is positively correlated with the severity of postpartum SUI;3.It is helpful to improve the predictive efficacy of postpartum SUI by combination of four pelvic floor indicators for comprehensive evaluation.