初探二维超声测量胎儿肾脏体积预测出生体重的方法
摘要
目的：探讨二维超声下以胎儿肾脏大小预测胎儿出生体重、评价胎儿生长发育状况的方法及其临床应用价值。
方法：以二维实时超声测量319例胎儿的双顶径、头围、腹围、股骨长径、双侧肾脏长径、横径及厚径，并计算每个胎肾体积。所有超声测量及检查均在胎儿娩出前72小时内完成。分析胎肾体积与出生体重的相关性，以胎肾体积为自变量，出生体重为因变量绘制散点图，经趋势拟合建立表示二者相关的最适公式，比较此公式与临床常用公式预测出生体重的准确性。比较适于胎龄儿、小于胎龄儿、大于胎龄儿肾脏的各个径线，根据小于胎龄儿肾脏的形态学特点，寻找可以用来预测小于胎龄儿的非孕龄依赖性指标。另收集150例胎儿作为验证组初步验证所得结果。
结果：胎肾体积与出生体重呈线性正相关(r=0.89，n=319，p＜0.05)，表示二者相关的公式比临床常用公式预测出生体重的准确性更高(绝对误差191.1g，相对误差5.9％)，特别是对巨大儿出生体重的预测具有独特优势(绝对误差157.0g，相对误差3.7％)。本研究中，小于胎龄儿肾脏的形态学改变与文献报道一致，呈“香肠形”，据此找到可以用来预测小于胎龄儿的非孕龄依赖性指标—肾长径／肾横径比值，当肾长径／肾横径≥1.78时预测小于胎龄儿的敏感度为80％，特异度为99.3％。上述结果在验证组中证实具有可重复性。
结论：二维超声下利用胎儿肾体积预测出生体重是可行的，此方法提高了预测巨大儿出生体重的准确性；当非孕龄依赖性指标—肾长径／肾横径≥1.78时，可初步考虑胎儿为小于胎龄儿，为临床提供简便、快捷的方法评价胎儿生长发育状况，但此值仍需更大样本进一步修正。
Objective: To investigate the methods of predicting fetal birth weight and fetal growth with fetal kidney size assessed by two-dimensional ultrasound.
Methods: The biparietal diameter, head circumference, abdominal circumference, femur length, bilateral kidney length, kidney width and kidney thickness of 319 singleton fetuses were measured by two-dimensional ultrasound. Bilateral kidney volume of all fetuses was calculated. All infants were delivered within 72 hours after the ultrasound examinations. The correlation between the kidney volume and the birth weight was analyzed. Using kidney volume as the independent variable and birth weight as the dependent variable, scattergrams was made by Excel. A best-fit formula was generated for the kidney volume to predict birth weight from polynomial regression analysis. The accuracy of the kidney-volume formula was compared with those of two formulas commonly used in clinical practices. Comparing kidney's every diameter of appropriate for gestational age fetal with that of small for gestational age fetal to look for an age-independent predictor of small for gestational age infant. In addition, another group of 150
fetuses was measured for prospective validation.
Results: The fetal kidney volume assessed by two-dimensional ultrasound was highly correlated with birth weight (r=0.89, n=319, p<0.05). The best-fit formula for kidney volume to predict birth weight was linear. Its predicting absolute error (191-.1g) and absolute percent error (5.9%) were all smaller than those of the other
two formulas. It was superior to the other commonly used two-dimensional formulas in predicting macrosomia birth weight (absolute error was 157.0g and absolute percent error was 3.7%). The result that small for gestational age fetal always has altered renal morphology, producing 'sausage-shaped' kidneys is similar as other literatures'. Kidney length to kidney width ratio can predict small for gestational age infant as an age-independent index. The cut-off value was 1.78. Its sensitivity and specificity of predicting small for gestational age infant was 80% and 99.3%, respectively. In addition, these results were also confirmed in the prospective-validation group.
Conclusions: It is possible of predicting birth weight with kidney volume assessed by two-dimensional ultrasound, and it may improve the accuracy of macrosomia weight prediction in clinical practice. However, a large-scale prospective validation study may be needed to reconfirm the conclusion of kidney length to kidney width ratio as an age-independent predictor for small for gestational age infant.
方法：以二维实时超声测量319例胎儿的双顶径、头围、腹围、股骨长径、双侧肾脏长径、横径及厚径，并计算每个胎肾体积。所有超声测量及检查均在胎儿娩出前72小时内完成。分析胎肾体积与出生体重的相关性，以胎肾体积为自变量，出生体重为因变量绘制散点图，经趋势拟合建立表示二者相关的最适公式，比较此公式与临床常用公式预测出生体重的准确性。比较适于胎龄儿、小于胎龄儿、大于胎龄儿肾脏的各个径线，根据小于胎龄儿肾脏的形态学特点，寻找可以用来预测小于胎龄儿的非孕龄依赖性指标。另收集150例胎儿作为验证组初步验证所得结果。
结果：胎肾体积与出生体重呈线性正相关(r=0.89，n=319，p＜0.05)，表示二者相关的公式比临床常用公式预测出生体重的准确性更高(绝对误差191.1g，相对误差5.9％)，特别是对巨大儿出生体重的预测具有独特优势(绝对误差157.0g，相对误差3.7％)。本研究中，小于胎龄儿肾脏的形态学改变与文献报道一致，呈“香肠形”，据此找到可以用来预测小于胎龄儿的非孕龄依赖性指标—肾长径／肾横径比值，当肾长径／肾横径≥1.78时预测小于胎龄儿的敏感度为80％，特异度为99.3％。上述结果在验证组中证实具有可重复性。
结论：二维超声下利用胎儿肾体积预测出生体重是可行的，此方法提高了预测巨大儿出生体重的准确性；当非孕龄依赖性指标—肾长径／肾横径≥1.78时，可初步考虑胎儿为小于胎龄儿，为临床提供简便、快捷的方法评价胎儿生长发育状况，但此值仍需更大样本进一步修正。
Objective: To investigate the methods of predicting fetal birth weight and fetal growth with fetal kidney size assessed by two-dimensional ultrasound.
Methods: The biparietal diameter, head circumference, abdominal circumference, femur length, bilateral kidney length, kidney width and kidney thickness of 319 singleton fetuses were measured by two-dimensional ultrasound. Bilateral kidney volume of all fetuses was calculated. All infants were delivered within 72 hours after the ultrasound examinations. The correlation between the kidney volume and the birth weight was analyzed. Using kidney volume as the independent variable and birth weight as the dependent variable, scattergrams was made by Excel. A best-fit formula was generated for the kidney volume to predict birth weight from polynomial regression analysis. The accuracy of the kidney-volume formula was compared with those of two formulas commonly used in clinical practices. Comparing kidney's every diameter of appropriate for gestational age fetal with that of small for gestational age fetal to look for an age-independent predictor of small for gestational age infant. In addition, another group of 150
fetuses was measured for prospective validation.
Results: The fetal kidney volume assessed by two-dimensional ultrasound was highly correlated with birth weight (r=0.89, n=319, p<0.05). The best-fit formula for kidney volume to predict birth weight was linear. Its predicting absolute error (191-.1g) and absolute percent error (5.9%) were all smaller than those of the other
two formulas. It was superior to the other commonly used two-dimensional formulas in predicting macrosomia birth weight (absolute error was 157.0g and absolute percent error was 3.7%). The result that small for gestational age fetal always has altered renal morphology, producing 'sausage-shaped' kidneys is similar as other literatures'. Kidney length to kidney width ratio can predict small for gestational age infant as an age-independent index. The cut-off value was 1.78. Its sensitivity and specificity of predicting small for gestational age infant was 80% and 99.3%, respectively. In addition, these results were also confirmed in the prospective-validation group.
Conclusions: It is possible of predicting birth weight with kidney volume assessed by two-dimensional ultrasound, and it may improve the accuracy of macrosomia weight prediction in clinical practice. However, a large-scale prospective validation study may be needed to reconfirm the conclusion of kidney length to kidney width ratio as an age-independent predictor for small for gestational age infant.
引文
1 Hadlock FP. Sonographic estimation of fetal age and weight. Radiol Clin North Am. 1990;28:39-50.
2 刘斌，高英茂，人体胚胎学．北京：人民卫生出版社．1995．
3 刘智，常才．超声测量不同孕周胎儿肝脏的长度及其临床意义．中华妇产科杂志．2001，36(3)：140-142．
4 Lampl M, Kuzawa CW, Jeanty P. Infants thinner at birth exhibit smaller kidneys for their size in late gestation in a sample of fetuses with appropriate growth. Am J Human Biol. 2002,14(3):398-406.
5 Yu C, Chang C, Chang F, et al. Fetal renal volume in normal gestation: a three-dimensional ultrasound study. Ultrasound Med Biol. 2000;26(8): 1253-6.
6 Gloor JM, Breckle RJ, Gehrking WC et al. Fetal renal growth evaluated by prenatal ultrasound examination. Mayo Clin Proc. 1997,72(2): 124-9.
7 Yao Yuan Hsieh, Chi Chen Chang MD, Chien Chung Lee MD et al. Fetal renal volume assessment by three-dimensional ultrasonography. Am J Obstet Gynecol. 2000,182(2):377-379.
8 Warsof SL, Gohan P, Berkowitz RL et al. The estimation of fetal weight by computer-assisted analysis. Am J Obstet Gynecol. 1977; 128:881-92.
9 Hadloek FP, Harrist FB, Shearman RS et al. Estimation of fetal weight with the use of head, body and femur measurements: A prospective study. Am J Obstet Gynecol. 1985; 151:333-7.
10 金汉珍等．实用新生儿科学，第二版．北京：人民卫生出版社，1996．
11 Rumack Carol M, Wilson Stephanie R, Charbonean J William et al. Diagnostic
ultrasound(Volume two). Von Hoffman Press, Inc.
12 耿贯一．流行病学(第四版)．北京：人民卫生出版社．1996．
13 吴钟瑜．实用妇产科超声诊断学(修订版)．天津科技翻译出版公司．1995．
14 洁萍，戴钟英．B型超声预测胎儿体重的研究进展．中华妇产科杂志．1997，32(6)：380-382．
15 Alonso K, Portman E. Fetal weights and measurements as determined by postmortem examination and their correlation with ultrasound examination. Arch-Pathol Lab Med. 1995, Feb; 119(2): 179-80.
16 Harris L. Cohen, James Cooper, Peter Eisenberg et al. Normal Length of Fetal Kidneys: Sonographic Study in 397 Obstetric Patients. AJR. 1991, 157: 545-548.
17 窦发坦，刘凤照，李若华．胎儿肾脏的B型超声检测．中国超声医学杂志．1995，11(2)：145-146．
18 Riccabona M, Nelson TR, Pretorius DH et al. In vivo three-dimensional sonographic measurement of organ volume: Validation in the urinary bladder. J Ultrasound Med 1996; 15: 627-32.
19 King DL, King DL, Shao MYC. Evaluation of in vitro measurement accuracy of a three-dimensional ultrasound scanner. J Ultrasound Med. 1991; 10: 77-82.
20 Riccabona M, Nelson TR, Pretorius DH et al. Distance and volume measurement using three-dimensional ultrasonography. J Ultrasound Med. 1995; 14: 881-6.
21 Sampaio F.J.B. Analysis of kidney volume growth during the fetal period in humans. Urol Res. 1992, 20: 271-274.
22 王慕狄．儿科学(第四版)．北京：人民卫生出版社．1996．
23 Seeds MD, John W. Impaired fetal growth: definition and clinical diagnosis.
Obstetrucs and Gynecology. 1984, 64(3) :303-309．
24 William J, Meyer MD, Daniel Gauthier MD et al. Ultrasonographic detection of abnormal fetal growth with the gestational age-independent, transverse cerebellar diameter/abdominal circumference ratio. Am J Obstet Gynecol. 1994,171(4) : 1057-1063．
25 Hadlock FP, Deter RL, Harrist RB et al. A date-independent predictor of intrauterine growth retardation: femur length/abdominal circumference ratio. AJR Am J Roentgenol 1983; 141:979-84．
26 Konje JC, Okaro CI, Bell SC et al. A cross-sectional study of changes in fetal renal size with gestation in appropriate-and small-for-gestation-age fetuses. Ultrasound Obstet Gynecol. 1997 Jul; 10(l):22-6．
2 刘斌，高英茂，人体胚胎学．北京：人民卫生出版社．1995．
3 刘智，常才．超声测量不同孕周胎儿肝脏的长度及其临床意义．中华妇产科杂志．2001，36(3)：140-142．
4 Lampl M, Kuzawa CW, Jeanty P. Infants thinner at birth exhibit smaller kidneys for their size in late gestation in a sample of fetuses with appropriate growth. Am J Human Biol. 2002,14(3):398-406.
5 Yu C, Chang C, Chang F, et al. Fetal renal volume in normal gestation: a three-dimensional ultrasound study. Ultrasound Med Biol. 2000;26(8): 1253-6.
6 Gloor JM, Breckle RJ, Gehrking WC et al. Fetal renal growth evaluated by prenatal ultrasound examination. Mayo Clin Proc. 1997,72(2): 124-9.
7 Yao Yuan Hsieh, Chi Chen Chang MD, Chien Chung Lee MD et al. Fetal renal volume assessment by three-dimensional ultrasonography. Am J Obstet Gynecol. 2000,182(2):377-379.
8 Warsof SL, Gohan P, Berkowitz RL et al. The estimation of fetal weight by computer-assisted analysis. Am J Obstet Gynecol. 1977; 128:881-92.
9 Hadloek FP, Harrist FB, Shearman RS et al. Estimation of fetal weight with the use of head, body and femur measurements: A prospective study. Am J Obstet Gynecol. 1985; 151:333-7.
10 金汉珍等．实用新生儿科学，第二版．北京：人民卫生出版社，1996．
11 Rumack Carol M, Wilson Stephanie R, Charbonean J William et al. Diagnostic
ultrasound(Volume two). Von Hoffman Press, Inc.
12 耿贯一．流行病学(第四版)．北京：人民卫生出版社．1996．
13 吴钟瑜．实用妇产科超声诊断学(修订版)．天津科技翻译出版公司．1995．
14 洁萍，戴钟英．B型超声预测胎儿体重的研究进展．中华妇产科杂志．1997，32(6)：380-382．
15 Alonso K, Portman E. Fetal weights and measurements as determined by postmortem examination and their correlation with ultrasound examination. Arch-Pathol Lab Med. 1995, Feb; 119(2): 179-80.
16 Harris L. Cohen, James Cooper, Peter Eisenberg et al. Normal Length of Fetal Kidneys: Sonographic Study in 397 Obstetric Patients. AJR. 1991, 157: 545-548.
17 窦发坦，刘凤照，李若华．胎儿肾脏的B型超声检测．中国超声医学杂志．1995，11(2)：145-146．
18 Riccabona M, Nelson TR, Pretorius DH et al. In vivo three-dimensional sonographic measurement of organ volume: Validation in the urinary bladder. J Ultrasound Med 1996; 15: 627-32.
19 King DL, King DL, Shao MYC. Evaluation of in vitro measurement accuracy of a three-dimensional ultrasound scanner. J Ultrasound Med. 1991; 10: 77-82.
20 Riccabona M, Nelson TR, Pretorius DH et al. Distance and volume measurement using three-dimensional ultrasonography. J Ultrasound Med. 1995; 14: 881-6.
21 Sampaio F.J.B. Analysis of kidney volume growth during the fetal period in humans. Urol Res. 1992, 20: 271-274.
22 王慕狄．儿科学(第四版)．北京：人民卫生出版社．1996．
23 Seeds MD, John W. Impaired fetal growth: definition and clinical diagnosis.
Obstetrucs and Gynecology. 1984, 64(3) :303-309．
24 William J, Meyer MD, Daniel Gauthier MD et al. Ultrasonographic detection of abnormal fetal growth with the gestational age-independent, transverse cerebellar diameter/abdominal circumference ratio. Am J Obstet Gynecol. 1994,171(4) : 1057-1063．
25 Hadlock FP, Deter RL, Harrist RB et al. A date-independent predictor of intrauterine growth retardation: femur length/abdominal circumference ratio. AJR Am J Roentgenol 1983; 141:979-84．
26 Konje JC, Okaro CI, Bell SC et al. A cross-sectional study of changes in fetal renal size with gestation in appropriate-and small-for-gestation-age fetuses. Ultrasound Obstet Gynecol. 1997 Jul; 10(l):22-6．