Nuffield Department of Obstetrics & Gynaecology, University of Oxford, Oxford, UK.
Placenta. 2012 Oct;33(10):782-7. doi: 10.1016/j.placenta.2012.07.005. Epub 2012 Jul 24.
Our current knowledge of the physiological dilatation of spiral arteries in pregnancy, is based on histology. Real-time ultrasound visualisation of these changes may aid understanding of abnormal placentation. This study aimed to investigate if changes in the spiral artery blood flow can be followed 'in vivo' and explore the novel phenomenon of the larger 'mega-jets'.
Colour Doppler ultrasonography was used to identify the most prominent jets at blood from the spiral artery into the intervillous space. Their velocity, width and length were recorded seven set time points during pregnancy.
Fifty two uncomplicated, term normotensive pregnancies were studied. Width and length of the jets' Doppler signals increased with gestation, the velocity decreased. The length of the jets shows a bi-modal frequency distribution. The width of the signals of longer ('mega') jets was significantly greater (p = 0.001) than that of the jets (mean 4.3 mm (3.1-5.9) versus 3.8 mm (1.8-5.8) respectively) at 34 weeks. However, there was no significant difference in the peak systolic velocity (p = 0.2).
This study confirms that ultrasound can be used to study the gestation dependent changes in the haemodynamics of the placental basal plate predicted, but not proven, by histologic data. The bi-modal distribution of jet lengths suggests that mega-jets are a separate entity to 'normal' jets. That they are significantly wider than 'normal' jets and yet maintain the same velocity of blood flow suggests that they have a greater volume of blood flow. The mechanism for this is hypothesised and their apparent relationship with simple placental lakes discussed.
我们目前对妊娠期间螺旋动脉生理性扩张的认识基于组织学。实时超声可视化这些变化可能有助于理解异常胎盘形成。本研究旨在探讨是否可以“在体”观察螺旋动脉血流的变化，并探索较大的“巨型射流”这一新颖现象。
采用彩色多普勒超声检查识别螺旋动脉血流进入绒毛间隙最突出的射流。记录妊娠 7 个时间点的血流速度、宽度和长度。
研究了 52 例无并发症的足月正常血压妊娠。射流的多普勒信号的宽度和长度随妊娠而增加，速度降低。射流的长度呈双峰频率分布。较长（“巨型”）射流信号的宽度明显大于（p=0.001）较短射流（分别为 4.3mm（3.1-5.9）和 3.8mm（1.8-5.8）），34 周时差异有统计学意义。然而，峰值收缩速度（p=0.2）无显著差异。
本研究证实，超声可用于研究胎盘基底板血流动力学随妊娠的变化，这是组织学数据预测但未证实的。射流长度的双峰分布表明巨型射流是与“正常”射流不同的实体。它们比“正常”射流宽得多，但仍保持相同的血流速度，表明它们具有更大的血流体积。假设了这种机制，并讨论了它们与简单胎盘湖之间的明显关系。
