Hedriana H L, Moore T R
Division of Perinatal Medicine, University of California, San Diego, CA.
Am J Obstet Gynecol. 1994 Jun;170(6):1600-4; discussion 1604-6. doi: 10.1016/s0002-9378(94)70329-9.
Our purpose was to determine whether two or more ultrasonographic fetal growth assessments provide a superior estimate of birth weight than does a single examination.
Five hundred and eighty five ultrasonographic procedures were performed in 263 patients, divided into single (n = 249) and multiple (n = 247) examination groups. Ultrasonographically estimated fetal weight percentiles and abdominal circumference percentiles were compared with gestationally corrected birth weight percentiles. After the gestational age range with the fewest errors in birth weight percentile prediction (32 to 36 weeks) was determined, patients with a single examination in this range were assigned to the single examination group. In the group with multiple examinations averaged ultrasonographic percentiles were used to predict birth weight percentile. Mean absolute and percentage errors were compared for predictive accuracy by means of analysis of variance and Student t test.
There was a linear correlation between the estimated fetal weight and abdominal circumference percentiles and the birth weight percentile, (r = 0.72, p < 0.0001). The accuracy of birth weight percentile predictions was similar whether one or multiple examinations were performed in the third trimester. Both the abdominal circumference percentile and estimated fetal weight percentile underpredicted birth weight, although the abdominal circumference percentile errors (1% to 2%) were statistically smaller than those derived from estimated fetal weights percentile (9% to 11%, p < 0.0001). Both abdominal circumference percentile and estimated fetal weights percentile consistently overidentified fetuses < 10th percentile (small for gestational age) and underidentified fetuses > 90th percentile (large for gestational age). However, multiple abdominal circumference percentile measurements resulted in improved predictions for small for gestational age (sensitivity 100%, specificity 88%) and large for gestational age (sensitivity 84%, specificity 100%).
With either the single or multiple examination approach birth weight percentile estimates were within 10% of the actual birth weight percentile approximately 50% of the time. Multiple ultrasonographic examinations provided little improvement in prediction of birth weight compared with a single observation. Multiple measurements of the abdominal circumference percentile may provide improved accuracy in identifying large for gestational age and small for gestational age fetuses.
我们的目的是确定两次或更多次超声胎儿生长评估对出生体重的估计是否比单次检查更准确。
对263例患者进行了585次超声检查，分为单次检查组（n = 249）和多次检查组（n = 247）。将超声估计的胎儿体重百分位数和腹围百分位数与经孕周校正的出生体重百分位数进行比较。在确定出生体重百分位数预测误差最少的孕周范围（32至36周）后，将在此范围内进行单次检查的患者分配到单次检查组。在多次检查组中，使用平均超声百分位数来预测出生体重百分位数。通过方差分析和学生t检验比较平均绝对误差和百分比误差的预测准确性。
估计的胎儿体重和腹围百分位数与出生体重百分位数之间存在线性相关性（r = 0.72，p < 0.0001）。无论在孕晚期进行一次还是多次检查，出生体重百分位数预测的准确性相似。腹围百分位数和估计的胎儿体重百分位数均低估了出生体重，尽管腹围百分位数的误差（1%至2%）在统计学上小于估计的胎儿体重百分位数的误差（9%至11%，p < 0.0001）。腹围百分位数和估计的胎儿体重百分位数均持续过度识别小于第10百分位数的胎儿（小于孕周）和未识别大于第90百分位数的胎儿（大于孕周）。然而，多次腹围百分位数测量可改善对小于孕周（敏感性100%，特异性88%）和大于孕周（敏感性84%，特异性100%）的预测。
采用单次或多次检查方法时，出生体重百分位数估计约50%的时间在实际出生体重百分位数的10%以内。与单次观察相比，多次超声检查在出生体重预测方面几乎没有改善。多次测量腹围百分位数可能会提高识别大于孕周和小于孕周胎儿的准确性。
