Crown-Rump Length
Embryology - 25 Apr 2024 Expand to Translate |
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Introduction
(CRL) A measurement used in embryology to more accurately stage the early embryo, also historically called the "greatest length" (GL). Measured from the curvature at the top (crown) to the curvature at the bottom (rump) of the "C-shaped" early embryo.
Modern measurements in clinical medicine are based upon ultrasound as a measurement between the periods of 7 to 13 weeks as an accurate estimation of the GA gestational age.
Links: embryonic | Carnegie Stage Comparison | ultrasound | Carnegie Institution - Contributions to Embryology | Human Embryo Collections |
Some Recent Findings
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More? References | Discussion Page | Journal Searches | 2019 References | 2020 References Search term: Crown-Rump Length <pubmed limit=5>Crown-Rump%20Length</pubmed> |
Ultrasound CRL
Note that clinical GA gestational age is about 2 weeks more than the fertilisation age.
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Gestational Age and Crown-Rump Length (measured by ultrasound) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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- Links: CRL-GA Table | FA-GA-CRL
Historic Embryo CRL
Mall (1918)[3] | Streeter (1920) Graph of embryo CRL[4] |
Embryo CRL 11 - 23
This graph showing change in CRL during the embryonic period is based upon the Carnegie Collection embryos from a later 1957 paper by Streeter.[5]
Fetal CRL
Third Trimester CRL
Postnatal
INTERGROWTH - 21st and the World Health Organization Multicentre Growth Reference Study[1]
- Three recently completed longitudinal cohort studies have developed intrauterine fetal growth charts
- one in the United States and two international.
- expert review compares and contrasts the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies, INTERGROWTH-21st and World Health Organization Multicentre Growth Reference Study conclusions
- area of controversy is whether a single growth reference is representative of growth, regardless of ethnic or country origin. * INTERGROWTH and World Health Organization Fetal studies used a similar approach as the World Health Organization Multicentre Growth Reference Study for infants and children, the aim of which was to create a single international reference for the best physiological growth for children aged 0-5 years.
- INTERGROWTH found differences in crown-rump length and head circumference among countries but interpreted the differences as not meaningful and presented a pooled standard.
- recognition of the fact that fetal size is commonly estimated from dimensions (head circumference, abdominal circumference, and femur length) in which there are known differences in children and adults of differing racial/ethnic groups.
- the percentiles for fetal dimensions and estimated fetal weight varied among the studies.
- 39 weeks - the 50th percentile for estimated fetal weight
- Eunice Kennedy Shriver National Institute of Child Health and Human Development Study - 3502 g for whites, 3330 g for Hispanics, 3263 g for Asians, and 3256 for blacks
- INTERGROWTH - 3186 g
- World Health Organization Multicentre Growth Reference Study - 3403 g
- Links: INTERGROWTH-21st
References
- ↑ 1.0 1.1 Grantz KL, Hediger ML, Liu D & Buck Louis GM. (2018). Fetal growth standards: the NICHD fetal growth study approach in context with INTERGROWTH-21st and the World Health Organization Multicentre Growth Reference Study. Am. J. Obstet. Gynecol. , 218, S641-S655.e28. PMID: 29275821 DOI.
- ↑ Westerway SC, Davison A & Cowell S. (2000). Ultrasonic fetal measurements: new Australian standards for the new millennium. Aust N Z J Obstet Gynaecol , 40, 297-302. PMID: 11065037
- ↑ Mall FP. On the age of human embryos. (1918) Amer. J Anat. 23: 397-422.
- ↑ Streeter GL. Weight, sitting height, head size, foot length, and menstrual age of the human embryo. (1920) Contrib. Embryol., Carnegie Inst. Wash. Publ. , : 143-170.
- ↑ Streeter GL. Developmental Horizons In Human Embryos Description Or Age Groups XIX, XX, XXI, XXII, And XXIII, Being The Fifth Issue Of A Survey Of The Carnegie Collection. (1957) Carnegie Instn. Wash. Publ. 611, Contrib. Embryol., 36: 167-196.
Journals
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Search Pubmed: Crown-Rump Length | Crown Rump Length
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Cite this page: Hill, M.A. (2024, April 25) Embryology Crown-Rump Length. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Crown-Rump_Length
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G