Taipale P, Hiilesmaa V, Ylöstalo P
Department of Obstetrics and Gynecology, Jorvi Hospital, Espoo, Finland.
Obstet Gynecol. 1997 Mar;89(3):364-7. doi: 10.1016/S0029-7844(96)00503-0.
To evaluate the clinical significance of placenta previa at 12-16 weeks' gestation found by transvaginal sonographic screening.
An unselected population of 6428 pregnant women was scanned by transvaginal sonography during 1993-1994 to assess the gestational age and to diagnose major fetal anomalies. The location of the placenta was also recorded systematically. If the edge of the placenta extended over the internal cervical os, this distance was measured with electronic calipers.
In 156 of 6428 patients (2.4%), the placental edge extended 15 mm or more over the internal cervical os at 12-16 weeks' gestation. Eight of these patients had placenta previa at delivery. Using this criterion at screening, two cases of placenta previa at delivery were missed. The frequency of placenta previa at delivery in this nonselected population was ten of 6428 (0.16%).
The likelihood of placenta previa at delivery is 5.1% (95% confidence interval 2.2, 9.9) if the placenta extends at least 15 mm over the internal cervical os at 12-16 weeks' gestation.
评估经阴道超声筛查发现的妊娠12 - 16周前置胎盘的临床意义。
1993年至1994年期间，对6428名未经过挑选的孕妇进行经阴道超声检查，以评估孕周并诊断主要胎儿畸形。同时系统记录胎盘位置。若胎盘边缘延伸至宫颈内口上方，用电子卡尺测量该距离。
6428例患者中有156例（2.4%）在妊娠12 - 16周时胎盘边缘延伸至宫颈内口上方15毫米或更多。其中8例患者分娩时为前置胎盘。以此标准进行筛查时，漏诊了2例分娩时的前置胎盘。该未经过挑选人群中分娩时前置胎盘的发生率为6428例中有10例（0.16%）。
如果妊娠12 - 16周时胎盘边缘延伸至宫颈内口上方至少15毫米，分娩时前置胎盘的可能性为5.1%（95%可信区间2.2，9.9）。
