Gillieson M S, Winer-Muram H T, Muram D
Radiology. 1982 Aug;144(3):577-80. doi: 10.1148/radiology.144.3.7100476.
Routine ultrasonographic examinations were performed in 255 pregnant women. Most of the patients (95%) had the examination prior to 32 weeks of gestation. In 16 patients (6%) the placenta was identified as low-lying placenta or placenta previa. Of those 16 patients, the placenta was located on the anterior wall in 6, on the posterior wall in 7, and on both the anterior and posterior walls in 3. Ultrasonographic follow-up examination showed conversion to normal position in 10 of those 16 patients (63%). Three of the 7 patients with posterior placentas and all 3 of the patients with placentas located on both posterior and anterior walls failed to demonstrate conversion of the placenta to a normal position. Bleeding complications were also more common in those 2 groups.
对255名孕妇进行了常规超声检查。大多数患者（95%）在妊娠32周前进行了检查。16名患者（6%）的胎盘被确定为低置胎盘或前置胎盘。在这16名患者中，胎盘位于前壁的有6例，后壁的有7例，前后壁均有的有3例。超声随访检查显示，这16名患者中有10例（63%）胎盘位置恢复正常。7例胎盘位于后壁的患者中有3例以及胎盘位于前后壁的所有3例患者，胎盘均未恢复到正常位置。这两组患者的出血并发症也更为常见。
