Fetal Weight Estimation in Extreme Macrosomia (≥ 4,500 g): Comparison of 10 Formulas

Abstract

Purpose: The aim of this retrospective study was to compare the accuracy of 10 commonly used weight estimation formulas in a group of fetuses with extreme macrosomia ( ≥ 4 500 g).

Materials and Methods: Ten formulas were evaluated in a group of 174 fetuses with a birth weight (BW) ≥ 4 500 g. Each fetus underwent ultrasound examination with complete biometric parameters within 7 days of delivery. The accuracy of the different formulas for fetal weight estimation (EFW) was compared by mean percentage error (MPE), median of the absolute percentage error (MAPE), the “limits-of-agreement” method and the percentage of EFW falling within the 10 % range of the true birth weight.

Results: MPE showed the largest deviation from zero with the Schild formula (MPE – 15.43 %) and the Shepard formula (MPE + 6.08 %) and was closest to zero with the Hadlock II formula (MPE – 5.34 %). The MPE of all formulas showed significant bias when compared to zero. All tested formulas, except the Shepard and Shinozuka equations, significantly underestimated fetal weight. The lowest MAPE was found for the Merz formula (7.23 %). The Hadlock II formula obtained the highest percentage of EWF within the 10 % range of the true birth weight (66.1 %).

Conclusion: Exact weight estimation in extreme macrosomia remains an unsolved problem, and can therefore only conditionally provide a sufficient basis for clinical decision processes.

Zusammenfassung

Ziel: Ziel dieser retrospektiven Studie war der Vergleich der Genauigkeit von 10 gängigen Gewichtsschätzungsformeln in einer Gruppe von Feten mit stark ausgeprägter Makrosomie ( ≥ 4 500 g).

Material und Methoden: Verglichen wurden 10 Formeln in einer Gruppe von 174 Feten mit einem Geburtsgewicht ≥ 4 500 g. Der Zeitabstand zwischen der vollständig durchgeführten Biometrie und der Entbindung lag bei allen Feten unter 8 Tagen. Um die Genauigkeit der verschiedenen Formeln zu testen und zu vergleichen, wurden folgende Parameter berechnet: mittlerer relativer Fehler (MPE), Median des absoluten Fehlers (MAPE), „limits-of-agreement“ und der Prozentsatz an Gewichtsschätzungen, der innerhalb 10 % des tatsächlichen Geburtsgewichtes lag.

Ergebnisse: Der MPE zeigte die größten Abweichungen bei Verwendung der Schild Formel (MPE – 15,43 %) und der Shepard Formel (MPE + 6,08 %), wohingegen die Hadlock II Formel (MPE – 5,34 %) die geringsten Abweichungen aufwies. Beim Vergleich gegen null zeigte der MPE aller Formeln einen signifikanten Fehler. Mit Ausnahme der Shepard und Shinozuka Formeln wurde das fetale Gewicht von allen Formeln signifikant unterschätzt. Während die Merz Formel den niedrigsten MAPE aufwies (7,23 %), ergab sich für die Hadlock II Berechnungen der höchste Prozentsatz an Gewichtsschätzungen, innerhalb 10 % des tatsächlichen Geburtsgewichtes (66,1 %).

Schlussfolgerung: Eine genaue Gewichtsschätzung, insbesondere bei den stark makrosomen Feten, ist mit den vorhanden Formeln nicht möglich und kann daher nur bedingt eine suffiziente Grundlage für klinische Entscheidungsprozesse darstellen.

Key words

ultrasound 2 D - observer performance - fetus - obstetrics

• References

• 1 Kramer MS, Morin I, Yang H et al. Why are babies getting bigger? Temporal trends in fetal growth and its determinants. J Pediatr 2002; 141: 538-542
• 2 Surkan PJ, Hsieh CC, Johansson AL et al. Reasons for increasing trends in large for gestational age births. Obstet Gynecol 2004; 104: 720-726
• 3 Oral E, Cagdas A, Gezer A et al. Perinatal and maternal outcomes of fetal macrosomia. Eur J Obstet Gynecol Reprod Biol 2001; 99: 167-171
• 4 Ecker JL, Greenberg JA, Norwitz ER et al. Birth weight as a predictor of brachial plexus injury. Obstet Gynecol 1997; 89: 643-647
• 5 Gilbert WM, Nesbitt TS, Danielsen B. Associated factors in 1611 cases of brachial plexus injury. Obstet Gynecol 1999; 93: 536-540
• 6 Peleg D, Hasnin J, Shalev E. Fractured clavicle and Erb’s palsy unrelated to birth trauma. Am J Obstet Gynecol 1997; 177: 1038-1040
• 7 ACOG Practice Bulletin No. 58. Ultrasonography in pregnancy. Obstet Gynecol 2004; 104: 1449-1458
• 8 Dudley NJ. A systematic review of the ultrasound estimation of fetal weight. Ultrasound Obstet Gynecol 2005; 25: 80-89
• 9 Siemer J, Egger N, Hart N et al. Fetal weight estimation by ultrasound: comparison of 11 different formulae and examiners with differing skill levels. Ultraschall in Med 2008; 29: 159-164
• 10 Kehl S, Korber C, Hart N et al. New Sonographic Method for Fetuses with a Large Abdominal Circumference Improves Fetal Weight Estimation. Ultraschall in Med 2010;
• 11 Siemer J, Peter W, Zollver H et al. How good is fetal weight estimation using volumetric methods?. Ultraschall in Med 2008; 29: 377-382
• 12 Schild RL, Fimmers R, Hansmann M. Fetal weight estimation by three-dimensional ultrasound. Ultrasound Obstet Gynecol 2000; 16: 445-452
• 13 Sood AK, Yancey M, Richards D. Prediction of fetal macrosomia using humeral soft tissue thickness. Obstet Gynecol 1995; 85: 937-940
• 14 Santolaya-Forgas J, Meyer WJ, Gauthier DW et al. Intrapartum fetal subcutaneous tissue/femur length ratio: an ultrasonographic clue to fetal macrosomia. Am J Obstet Gynecol 1994; 171: 1072-1075
• 15 Abramowicz JS, Sherer DM, Bar-Tov E et al. The cheek-to-cheek diameter in the ultrasonographic assessment of fetal growth. Am J Obstet Gynecol 1991; 165: 846-852
• 16 Melamed N, Yogev Y, Meizner I et al. Sonographic fetal weight estimation: which model should be used?. J Ultrasound Med 2009; 28: 617-629
• 17 Hoopmann M, Abele H, Wagner N et al. Performance of 36 different weight estimation formulae in fetuses with macrosomia. Fetal Diagn Ther 2010; 27: 204-213
• 18 Rosati P, Arduini M, Giri C et al. Ultrasonographic weight estimation in large for gestational age fetuses: a comparison of 17 sonographic formulas and four models algorithms. J Matern Fetal Neonatal Med 2010; 23: 675-680
• 19 Hadlock FP, Harrist RB, Carpenter RJ et al. Sonographic estimation of fetal weight. The value of femur length in addition to head and abdomen measurements. Radiology 1984; 150: 535-540
• 20 Siemer J, Wolf T, Hart N et al. Increased accuracy of fetal weight estimation with a gender-specific weight formula. Fetal Diagn Ther 2008; 24: 321-326
• 21 Eichhorn KH, Schramm T, Bald R et al. DEGUM grade I quality standards in obstetric ultrasound diagnosis during the 19th-22nd week of pregnancy. Ultraschall in Med 2006; 27: 185-187
• 22 Merz E, Eichhorn KH, Hansmann M et al. Quality demands on continuing differential diagnostic sonography in prenatal diagnostics (DEGUM stage II) during the 18th to 22nd weeks of gestation. Ultraschall in Med 2002; 23: 11-12
• 23 Snedecor GWCW. Comparison of two correlated variances in paired samples in Statistical Methods. Ames: Iowa State University Press; 1989: 192-193
• 24 Bland JMAD. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986; 1: 307-310
• 25 Benacerraf BR, Gelman R, Frigoletto FD et al. Sonographically estimated fetal weights: accuracy and limitation. Am J Obstet Gynecol 1988; 159: 1118-1121
• 26 Deter RL, Hadlock FP. Use of ultrasound in the detection of macrosomia: a review. J Clin Ultrasound 1985; 13: 519-524
• 27 Miller Jr. JM, Kissling GA, Brown HL et al. Estimated fetal weight: applicability to small- and large-for-gestational-age fetus. J Clin Ultrasound 1988; 16: 95-97
• 28 Mongelli M, Gardosi J. Gestation-adjusted projection of estimated fetal weight. Acta Obstet Gynecol Scand 1996; 75: 28-31
• 29 Hart NC, Hilbert A, Meurer B et al. Macrosomia: a new formula for optimized fetal weight estimation. Ultrasound Obstet Gynecol 35: 42-47
• 30 Kurmanavicius J, Burkhardt T, Wisser J et al. Ultrasonographic fetal weight estimation: accuracy of formulas and accuracy of examiners by birth weight from 500 to 5000g. J Perinat Med 2004; 32: 155-161
• 31 Coomarasamy A, Connock M, Thornton J et al. Accuracy of ultrasound biometry in the prediction of macrosomia: a systematic quantitative review. BJOG 2005; 112: 1461-1466
• 32 Dudley NJ, Chapman E. The importance of quality management in fetal measurement. Ultrasound Obstet Gynecol 2002; 19: 190-196
• 33 Smulian JC, Ranzini AC, Ananth CV et al. Comparison of three sonographic circumference measurement techniques to predict birth weight. Obstet Gynecol 1999; 93: 692-696
• 34 Petrikovsky BM, Oleschuk C, Lesser M et al. Prediction of fetal macrosomia using sonographically measured abdominal subcutaneous tissue thickness. J Clin Ultrasound 1997; 25: 378-382
• 35 Hasenoehrl G, Pohlhammer A, Gruber R et al. Fetal weight estimation by 2D and 3D ultrasound: comparison of six formulas. Ultraschall in Med 2009; 30: 585-590
• 36 Halaska MG, Vlk R, Feldmar P et al. Predicting term birth weight using ultrasound and maternal characteristics. Eur J Obstet Gynecol Reprod Biol 2006; 128: 231-235
• 37 Nahum GG, Stanislaw H, Huffaker BJ. Accurate prediction of term birth weight from prospectively measurable maternal characteristics. J Reprod Med 1999; 44: 705-712
• 38 Hadlock FP, Harrist RB, Sharman 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: 333-337
• 39 Merz E, Lieser H, Schicketanz KH et al. Intrauterine fetal weight assessment using ultrasound. A comparison of several weight assessment methods and development of a new formula for the determination of fetal weight.. Ultraschall in Med 1988; 9: 15-24
• 40 Sabbagha RE, Minogue J, Tamura RK et al. Estimation of birth weight by use of ultrasonographic formulas targeted to large-, appropriate-, and small-for-gestational-age fetuses. Am J Obstet Gynecol 1989; 160: 854-860 ; discussion 860–852
• 41 Schild RL, Sachs C, Fimmers R et al. Sex-specific fetal weight prediction by ultrasound. Ultrasound Obstet Gynecol 2004; 23: 30-35
• 42 Schillinger H, Muller R, Wode J et al. Intrauterine weight determination of the fetus using ultrasonics. Arch Gynakol 1975; 219: 399-401
• 43 Shepard MJ, Richards VA, Berkowitz RL et al. An evaluation of two equations for predicting fetal weight by ultrasound. Am J Obstet Gynecol 1982; 142: 47-54
• 44 Shinozuka N, Okai T, Kohzuma S et al. Formulas for fetal weight estimation by ultrasound measurements based on neonatal specific gravities and volumes. Am J Obstet Gynecol 1987; 157: 1140-1145
• 45 Warsof SL, Gohari P, Berkowitz RL et al. The estimation of fetal weight by computer-assisted analysis. Am J Obstet Gynecol 1977; 128: 881-892