Clementschitsch G, Hasenöhrl G, Schaffer H, Steiner H
Department of Obstetrics and Gynecology, Prenatal Diagnosis and Therapy Unit, St. Johannsspital Salzburg, Salzburg, Austria.
Ultrasound Obstet Gynecol. 2001 Nov;18(5):475-80. doi: 10.1046/j.0960-7692.2001.00566.x.
Fetal nuchal translucency measurement has been introduced as a screening test for the calculation of risk of chromosomal abnormalities. The purpose of this study was to investigate: (1) the feasibility of obtaining nuchal translucency measurements using three-dimensional ultrasound; (2) whether three-dimensional ultrasound could improve and facilitate the required repeated measurements of nuchal translucency; (3) the correlation between two- and three-dimensional nuchal translucency measurement values.
Between September 1999 and May 2000, in a prospective cohort study, 229 unselected pregnant women with a mean age of 34.6 (range, 20-46) years were examined. The mean fetal crown-rump length was 64.3 (range, 45-84) mm. Nuchal translucency thickness was measured first by two- and then by three-dimensional ultrasound in two planes (three-dimensional mid-sagittal and three-dimensional transverse). An attempt was made to repeat each nuchal translucency measurement three times (totalling nine measurements per patient) and the means of the two- and three-dimensional measurements were compared. The majority (95%) of the measurements were made transabdominally and 5% were made transvaginally. The time limit for each examination was 20 min.
With the two-dimensional method, nuchal translucency could be measured in 96.8% of cases. Of these, three measurements could be obtained in 51.7%, two in 23.2% and only one in 25.1%. The three-dimensional examination was successful in 98.6% of cases. Of these, three measurements could be obtained in 60%, two in 22.8% and one in 17.2%. Transvaginally, all examinations were successful. The main reason for the failure of two-dimensional ultrasound was the fetal position, which in some cases precluded the distinction between fetal skin and amnion or the uterine wall. Using two-dimensional ultrasound, 6.3% of the cases of measurement failure were due to an inability to differentiate clearly between fetal skin and amnion, whilst the equivalent value for the three-dimensional method was only 3.3%. For the three-dimensional technique, fetal movement was the main reason for failure. The mean time for both methods was similar (9 min and 10 min for two- and three-dimensional ultrasound, respectively) and the correlation between the measurements obtained by the two- and three-dimensional techniques was very high (r = 0.97).
The number of fetuses in which nuchal translucency could be measured tended to be higher with three-dimensional ultrasound, although the difference was not statistically significant. The possibility of rotating a stored volume and inspecting it in three orthogonal planes makes three-dimensional ultrasound a useful tool for nuchal translucency measurements, especially in doubtful cases.
胎儿颈部透明带测量已作为一种筛查试验用于计算染色体异常风险。本研究的目的是调查：（1）使用三维超声获取颈部透明带测量值的可行性；（2）三维超声是否能改善并便于进行所需的颈部透明带重复测量；（3）二维和三维颈部透明带测量值之间的相关性。
在1999年9月至2000年5月期间，进行了一项前瞻性队列研究，对229名未经选择的孕妇进行了检查，这些孕妇的平均年龄为34.6岁（范围20 - 46岁）。胎儿头臀长度平均为64.3毫米（范围45 - 84毫米）。首先通过二维超声，然后通过三维超声在两个平面（三维正中矢状面和三维横断面）测量颈部透明带厚度。尝试对每个颈部透明带测量重复三次（每位患者共九次测量），并比较二维和三维测量的平均值。大多数测量（95%）经腹部进行，5%经阴道进行。每次检查的时间限制为20分钟。
采用二维方法时，96.8%的病例能够测量颈部透明带。其中，51.7%的病例可获得三次测量值，23.2%可获得两次，25.1%仅能获得一次。三维检查在98.6%的病例中成功。其中，60%可获得三次测量值，22.8%可获得两次，17.2%可获得一次。经阴道检查时，所有检查均成功。二维超声检查失败的主要原因是胎儿位置，在某些情况下妨碍了区分胎儿皮肤与羊膜或子宫壁。使用二维超声时，6.3%的测量失败病例是由于无法清晰区分胎儿皮肤与羊膜，而三维方法的这一数值仅为3.3%。对于三维技术，胎儿活动是失败的主要原因。两种方法的平均检查时间相似（二维超声和三维超声分别为9分钟和10分钟），二维和三维技术获得的测量值之间的相关性非常高（r = 0.97）。
尽管差异无统计学意义，但三维超声能够测量颈部透明带的胎儿数量往往更高。能够旋转存储容积并在三个相互垂直的平面上进行检查，使得三维超声成为测量颈部透明带的有用工具，尤其是在疑难病例中。
