Chauhan S P, Washburne J F, Martin J N, Roberts W E, Roach H, Morrison J C
Department of Obstetrics and Gynecology, University of Mississippi Medical Center, Jackson.
Obstet Gynecol. 1993 Oct;82(4 Pt 1):523-6.
To determine among twins in labor: 1) the relative accuracy of an intrapartum sonographic estimate of the birth weight for both fetuses using biparietal diameter and abdominal circumference, 2) the accuracy of detecting discordant growth (difference in actual birth weights greater than or equal to 15%), and 3) the estimate of fetal weight for nonvertex twin B that would reliably avoid breech extraction of infants less than 1500 g.
Retrospectively, we identified and analyzed parturients with twins who had an intrapartum sonogram performed by a house officer assigned to the labor and delivery suite.
The mean birth weight (+/- standard deviation) for the twin A group was 1910 +/- 628 g and for twin B was 1869 +/- 668 g. The mean standardized absolute errors for the twin A group (121 +/- 118 g/kg) and the twin B group (92 +/- 67 g/kg) were not significantly different (P = .06). Analysis of variance revealed that regardless of the presentation of the fetuses, the mean standardized absolute error was not significantly different (P = .10). Using a difference in the estimates of birth weight of 15% or greater, the positive and negative predictive values of detecting discordant growth within a twin pair were 53 and 83%, respectively. Among 30 vertex-nonvertex twin pairs, 12 of the second fetuses had actual birth weights of 1500 g or less, and all were estimated to weigh less than 1700 g.
The intrapartum sonographic estimate of fetal weight in twin pregnancy by house staff appears reliable, and the accuracy of prediction is similar regardless of presentation, discordance, or actual birth weight greater or less than 1500 g. To avoid vaginal delivery of a persistent nonvertex twin B with a birth weight of 1500 g or less, a sonographic estimate of 1700 g for the second fetus may be adequate.
确定分娩时双胞胎的以下情况：1）使用双顶径和腹围对两个胎儿进行产时超声估计出生体重的相对准确性；2）检测生长不一致（实际出生体重差异大于或等于15%）的准确性；3）对非头位双胞胎B的胎儿体重估计，该估计应能可靠避免对体重小于1500g的婴儿进行臀位助产。
我们回顾性地识别并分析了由分配到产房的住院医师进行产时超声检查的双胞胎产妇。
双胞胎A组的平均出生体重（±标准差）为1910±628g，双胞胎B组为1869±668g。双胞胎A组（121±118g/kg）和双胞胎B组（92±67g/kg）的平均标准化绝对误差无显著差异（P = 0.06）。方差分析显示，无论胎儿的胎位如何，平均标准化绝对误差无显著差异（P = 0.10）。使用出生体重估计差异15%或更大，检测双胞胎对中生长不一致的阳性和阴性预测值分别为53%和83%。在30对头位-非头位双胞胎对中，12例第二个胎儿的实际出生体重为1500g或更低，且所有估计体重均小于1700g。
住院医护人员对双胎妊娠进行产时超声估计胎儿体重似乎是可靠的，无论胎位、不一致情况或实际出生体重高于或低于1500g，预测准确性相似。为避免对出生体重1500g或更低的持续性非头位双胞胎B进行阴道分娩，对第二个胎儿进行超声估计1700g可能就足够了。
