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. 2021 Sep;58(3):354-359.
doi: 10.1002/uog.23690.

Crown-rump length measurement error: impact on assessment of growth

K Gadsbøll  1   2 , A Wright  3 , S E Kristensen  1   2 , V Verfaille  4 , K H Nicolaides  5 , D Wright  3 , O B Petersen  1   2
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Free article

Crown-rump length measurement error: impact on assessment of growth

K Gadsbøll et al. Ultrasound Obstet Gynecol. 2021 Sep.
Free article

Abstract

Objective: To examine the impact of first-trimester crown-rump length (CRL) measurement error on the interpretation of estimated fetal weight (EFW) and classification of fetuses as small-, large- or appropriate-for-gestational age on subsequent growth scans.

Methods: We examined the effects of errors of ± 2, ± 3 and ± 4 mm in the measurement of fetal CRL on percentiles of EFW at 20, 32 and 36 weeks' gestation and classification as small-, large- or appropriate-for-gestational age. Published data on CRL measurement error were used to determine variation present in practice.

Results: A measurement error of -2 mm in first-trimester CRL shifts an EFW on the 10th percentile at the 20-week scan to around the 20th percentile, and the effect of a CRL measurement error of + 2 mm would shift an EFW on the 10th percentile to around the 5th percentile. At 32 weeks, a first-trimester CRL measurement error would shift an EFW on the 10th percentile to the 7th (+ 2 mm) or 14th (-2 mm) percentile; at 36 weeks, the EFW would shift from the 10th percentile to the 8th (+ 2 mm) or 12th (-2 mm) percentile. Published data suggest that measurement errors of 2 mm or more are common in practice.

Conclusion: Because of the widespread and potentially severe consequences of CRL measurement errors as small as 2 mm on clinical assessment, patient management and research results, there is a need to increase awareness of the impact of CRL measurement error and to reduce measurement error variation through standardization and quality control. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Keywords: crown-rump length; estimated fetal weight; growth scan; large-for-gestational age; measurement error; small-for-gestational age.

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References

REFERENCES

    1. Hall MH, Carr-Hill RA. The significance of uncertain gestation for obstetric outcome. Br J Obstet Gynaecol 1985; 92: 452-460.
    1. Kalish RB, Chervenak FA. Sonographic determination of gestational age. Ultrasound Rev Obstet Gynecol 2005; 5: 254-258.
    1. Morken NH, Skjaerven R, Richards JL, Kramer MR, Cnattingius S, Johansson S, Gissler M, Dolan SM, Zeitlin J, Kramer MS, Group PEW. Adverse Infant Outcomes Associated with Discordant Gestational Age Estimates. Paediatr Perinat Epidemiol 2016; 30: 541-549.
    1. Bennett KA, Crane JM, O'Shea P, Lacelle J, Hutchens D, Copel JA. First trimester ultrasound screening is effective in reducing postterm labor induction rates: a randomized controlled trial. Am J Obstet Gynecol 2004; 190: 1077-1081.
    1. Hoffman CS, Messer LC, Mendola P, Savitz DA, Herring AH, Hartmann KE. Comparison of gestational age at birth based on last menstrual period and ultrasound during the first trimester. Paediatr Perinat Epidemiol 2008; 22: 587-596.

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