穿透性胎盘植入并侵犯膀胱MRI征象

The analysis of diagnostic value of MRI features for the placenta percreta invading the urinary bladder

目的:探讨穿透性胎盘植入并侵犯膀胱MRI征象。方法:分析本院2014年1月-2017年12月经产前MRI检查诊断为植入型凶险性前置胎盘并经手术证实病例共86例,排除MRI检查显示膀胱充盈欠佳,选取膀胱呈半充盈状态病例共71例,以其中手术证实为穿透性胎盘植入并侵犯膀胱病例14例作为侵犯组,其余无膀胱侵犯病例共57例作为对照组,进行组间比较分析MRI征象统计学差异,并计算各征象诊断穿透性胎盘植入侵犯膀胱敏感度和特异度。结果:组间MRI征象两两比较分析胎盘母体面与膀胱浆膜面分界不清(侵犯组14/14、对照组26/57),膀胱子宫间隙脂肪带中断(侵犯组13/14、对照组29/57),膀胱后壁低信号带中断(侵犯组10/14、对照组3/57),膀胱子宫界面出现过多流空血管(列入对象为子宫膀胱间隙内流空血管、子宫膀胱界面处难以区分为胎盘下或子宫膀胱间隙流空血管,侵犯组14/14、对照组20/57),膀胱后壁见结节状或幕状突起(侵犯组12/14、对照组8/57),胎盘向膀胱方向膨凸(侵犯组14/14、对照组20/57),胎盘突入宫颈(侵犯组11/14、对照组22/57)等征象在两组间发生率差异均有统计学意义(P<0.05)。其中膀胱后壁见结节状或幕状突起、膀胱后壁低信号带中断、膀胱子宫间隙出现过多流空血管、胎盘向膀胱方向膨凸有较高敏感度和特异度,4种征象敏感度分别为85.7%、71.4%、100%、100%,特异度分别为86%、95%、64.9%、64.9%。胎盘下血管异常(列入对象为明确位于胎盘下的流空血管异常,侵犯组14/14、对照组53/57),胎盘内T2WI低信号条带(侵犯组14/14、对照组47/57)在两组间发生率差异无统计学意义(P>0.05)。结论:产前MRI征象对鉴别穿透性胎盘植入是否侵犯膀胱具有重要诊断价值。其中胎盘向膀胱方向膨凸、膀胱后壁低信号带中断、膀胱后壁见结节状或幕状突起、膀胱子宫间隙出现过多流空血管等MRI征象具有较高诊断效能。

Objective:To explore the MRI features of the placenta percreta invading the urinary bladder.Methods:A total of 86 cases of placenta previa confirmed by surgical pathology and examined by MRI in Shenzhen City Maternal and Child Health Hospitalfrom Jan,2014 to Dec,2017 were retrospectively analyzed.Excluding the cases with poor bladder filling revealed by MRI,a total of 71 cases with a semi-filled bladder were selected.14/71 cases of placenta previa with bladder invasion were selected as the invasion group,and the other 57/71 cases of no-bladder invasing as the control group.MRI features between the groups,and the sensitivity and specificity of the features for diagnosis of placenta percreta invading the urinary bladder were calculated.Results:There was statistical significance concerning the difference in MRI features,i.e.the infiltration of the maternal placenta and the serosal surface of the bladder(invasion group:14/14、control group:26/57),interrupted interstitial adipose band of bladder and uterus(invasion group:13/14、control group:29/57),disruption of the low signal band in the posterior wall of the bladder(invasion group:10/14、control group:3/57),abnormal increase of no-signal blood vessels between bladder and uterine invasion group:14/14、control group:20/57,significant circumscribed protuberantia of placenta combined with extrauterine contour nodular protuberance(invasion group:12/14、control group:8/57),uterine deformation and abnormal protuberantia to bladder(invasion group:14/14、control group:20/57),placental protrusion to cervix uteri(invasion group:11/14、control group:22/57),between the two groups(P<0.05).Therein the sensitivity and specificity of MRI features,i.e.disruption of the low signal band in the posterior wall of the bladder,abnormal increase of no-signal blood vessels between bladder and uterine,significant circumscribed protuberantia of placenta combined with extrauterine contour nodular protuberance,uterine deformation and abnormal protuberantia to bladder,were high for diagnosing placenta percreta invading the urinary bladder.The sensitivities were 85.7%,71.4%,100%and 100%,respectively,and the specificities were 86%,95%,64.9%and 64.9%,respectively.There was not statistical significance concerning the difference in the feature of abnormal subplacental vascularity and low signal intensity bands on T2WI(P>0.05).Conclusion:Prenatal MRI is of significant value in the differential diagnosis of the placenta percreta invade the urinary bladder.The MRI features of disruption of the low signal band in the posterior wall of the bladder,abnormal increase of no-signal blood vessels between bladder and uterine,significant circumscribed protuberantia of placenta combined with extrauterine contour nodular protuberance,uterine deformation and abnormal protuberantia to bladder,have high diagnostic efficiency.