Hertzberg B S, Bowie J D, Carroll B A, Kliewer M A, Weber T M
Department of Radiology, Duke University Medical Center, Durham, NC 27710.
AJR Am J Roentgenol. 1992 Jul;159(1):83-7. doi: 10.2214/ajr.159.1.1609727.
Placenta previa can be difficult to diagnose with transabdominal sonography during the third trimester of pregnancy, because of difficulties in imaging the cervix late in pregnancy. Although transperineal sonography offers an additional view of the cervix, its value in the diagnosis of placenta previa has not been studied. Accordingly, we performed transperineal sonography on 164 patients who had had transabdominal scans that had shown placenta previa or had been inconclusive during the third trimester of pregnancy. Transabdominal sonograms had been inconclusive for placenta previa in 157 of these patients because the cervix was not visualized. The remaining seven patients had transabdominal scans that showed placenta previa. Transperineal sonography successfully visualized the internal surface of the cervix in all 164 patients, allowing determination of the presence or absence of placenta previa in all cases. Transperineal sonograms showed absence of placenta previa in 154 patients. At delivery, none of these patients had evidence of placenta previa. Transperineal sonography showed placenta previa in 10 patients. In nine of these patients, placenta previa was confirmed at delivery. The 10th patient did not have clinically significant placenta previa at delivery. Our study shows that transperineal sonography is a valuable technique to complement transabdominal sonography for detection of placenta previa during the third trimester of pregnancy. Use of transperineal sonography should be strongly considered when a definitive diagnosis regarding placenta previa is not possible by transabdominal sonography because the cervix is not visualized. In such cases, transperineal sonography will usually show the internal surface of the cervix without overlying placental tissue, allowing confident exclusion of placenta previa. Occasionally, however, transperineal sonography will show a placenta previa that was not seen with transabdominal sonography.
妊娠晚期经腹超声检查难以诊断前置胎盘，因为妊娠晚期宫颈成像困难。虽然经会阴超声检查可提供宫颈的额外视野，但尚未研究其在前置胎盘诊断中的价值。因此，我们对164例妊娠晚期经腹超声检查显示前置胎盘或结果不明确的患者进行了经会阴超声检查。其中157例患者经腹超声检查对前置胎盘诊断结果不明确，因为宫颈未显影。其余7例患者经腹超声检查显示前置胎盘。经会阴超声检查成功显示了所有164例患者宫颈的内表面，从而在所有病例中确定了是否存在前置胎盘。经会阴超声检查显示154例患者不存在前置胎盘。分娩时，这些患者均无前置胎盘的证据。经会阴超声检查显示10例患者存在前置胎盘。其中9例患者分娩时证实为前置胎盘。第10例患者分娩时无临床意义的前置胎盘。我们的研究表明，经会阴超声检查是在妊娠晚期补充经腹超声检查以检测前置胎盘的一种有价值的技术。当经腹超声检查因宫颈未显影而无法对前置胎盘作出明确诊断时，应强烈考虑使用经会阴超声检查。在这种情况下，经会阴超声检查通常会显示宫颈内表面而无覆盖的胎盘组织，从而可以可靠地排除前置胎盘。然而，偶尔经会阴超声检查会显示经腹超声检查未发现的前置胎盘。
