Burger M, Weber-Rössler T, Willmann M
Department of Gynecology and Obstetrics, General Hospital of Korneuburg, Austria.
Ultrasound Obstet Gynecol. 1997 Mar;9(3):188-93. doi: 10.1046/j.1469-0705.1997.09030188.x.
Transvaginal sonography has become an important tool for assessing the gravid cervix uteri, especially in patients at risk for cervical incompetence and preterm delivery. The purpose of our prospective study was to evaluate interobserver variability in measurements of the cervical length and, as a second step, improve the reproducibility and interobserver discrepancy by the introduction of quality control standards when producing and measuring the image of the cervix. Before the introduction of these standards we obtained 46 measurements and observed a mean cervical length (internal to external os) of 33.7 mm (range 26-52 mm) and an interobserver average discrepancy of 3.04 mm (range 0-6 mm). Later, measurements were obtained only when the following conditions were assured and visualized on the screen: (1) the internal os is either flat or is an isosceles triangle; (2) the whole length of the cervical canal can be observed; (3) a symmetric image of the external os can be obtained; and (4) the distance from the surface of the posterior lip to the cervical canal is equal to the distance from the anterior lip to the cervical canal. After the implementation of these quality control standards, 70 measurements were performed obtaining a mean length of 35.3 mm (range 27-51) and an average interobserver discrepancy of 1.24 mm (range 0-4). Thus the measurement error was significantly lower following introduction of quality control standards. Furthermore, the coefficient of variation dropped from 7.1% to 3.3% after the introduction of the guidelines. We believe that these guidelines could be helpful by making the measurements of the cervical length more accurate, reducing the interobserver variability, improving the reproducibility and promoting the role of transvaginal sonography in monitoring the incompetent cervix.
经阴道超声检查已成为评估妊娠子宫颈的重要工具，尤其对于有宫颈机能不全和早产风险的患者。我们前瞻性研究的目的是评估观察者间在宫颈长度测量上的变异性，其次，通过在生成和测量宫颈图像时引入质量控制标准，提高测量的可重复性并减少观察者间的差异。在引入这些标准之前，我们进行了46次测量，观察到宫颈平均长度（宫颈内口至外口）为33.7毫米（范围为26 - 52毫米），观察者间平均差异为3.04毫米（范围为0 - 6毫米）。后来，仅在屏幕上确保并显示以下条件时才进行测量：（1）宫颈内口为扁平状或等腰三角形；（2）可观察到宫颈管的全长；（3）可获得宫颈外口的对称图像；（4）宫颈后唇表面至宫颈管的距离等于前唇至宫颈管的距离。实施这些质量控制标准后，进行了70次测量，平均长度为35.3毫米（范围为27 - 51毫米），观察者间平均差异为1.24毫米（范围为0 - 4毫米）。因此，引入质量控制标准后测量误差显著降低。此外，引入指导方针后变异系数从7.1%降至3.3%。我们认为这些指导方针可能有助于使宫颈长度测量更准确，减少观察者间的变异性，提高可重复性，并促进经阴道超声检查在监测宫颈机能不全中的作用。
