胎盘影像学表现(二).pptx

Imaging of the Placenta（二）胎盘影像学表现（二） Placenta Accreta胎盘植入During the process of placental development and implantation, a defect in the normal decidua basalis from prior surgery or instrumentation allows abnormal adherence or penetration of the chorionic villi to or into the uterine wall . 由于胎盘植入所造成的手术或仪器使用常常导致基底膜部分缺失，使绒毛膜异常粘着或穿透入子宫壁The extent of adherence to and invasion of the placental tissue varies: Super?cial invasion of the basalis layer is termed placenta accreta (approximately 75% of cases); deeper invasion of the myometrium is termed placenta increta; and even deeper invasion involving the serosa or adjacent pelvic organs is termed placenta percreta. 根据胎盘植入的程度可分为以下几种：表浅的基底膜受侵（约占75%）；子宫肌层受侵；子宫浆膜或子宫周围组织受侵This abnormal adherence of the placenta to the uterus can result in catastrophic intrapartum hemorrhage at the time of placental delivery, often necessitating emergent hysterectomy .胎盘植入常可导致分娩时出血Placenta Accreta胎盘植入US and Doppler imaging have been shown to be effective imaging strategies for the detection of placenta accreta when applied to a clinically high-risk population, such as those with prior uterine surgery or placenta previa. 超声和多普勒成像已经证实是诊断胎盘植入的有效检查手段，尤其是高危人群如曾有子宫手术史或前置胎盘史的患者 MR imaging is most useful in cases where the sonographic ?ndings are equivocal or when the placenta has a posterior location.MRI常应用于超声难以确诊或胎盘后置时MR imaging features considered diagnostic of placenta accreta include abnormal uterine bulging, heterogeneous placental signal intensity on T2-weighted images, and the presence of dark intraplacental bands related to lacunae on T2-weighted images. MRI诊断胎盘植入的特征主要是胎盘增生，包括子宫异常隆起,T2上盈盘信号不均，以及胎盘边缘黑色的裂隙 (b) MR image shows intermediate-signal-intensity placental tissue (arrowhead) invading the normal dark myometrium (M) in the lower uterine segment. (c) Sagittal MR image shows obliteration of the normal dark myometrium (M) posteriorly, with placental tissue of heterogeneous signal intensity (arrowheads) penetrating the full thickness of the ute