Crown-rump length

Crown-rump length (CRL) is a measurement of the length of human embryos and fetuses from the top of the head (crown) to the bottom of the buttocks (rump). It is typically determined from ultrasound imagery and can be used to estimate gestational age.

Measurement

The crown-rump length is typically measured during the first trimester of pregnancy, between the 7th and 13th week of gestation. The measurement is taken from the top of the head to the bottom of the buttocks, which is the longest length of the embryo or fetus at this stage of development. The CRL is reported to be accurate within 3 to 5 days of gestational age.

Clinical significance

The crown-rump length is a fundamental measurement in pregnancy and is used to estimate the gestational age of the fetus. It can also be used to screen for potential abnormalities in fetal growth. A CRL that is significantly smaller or larger than expected for the gestational age may indicate a potential problem, such as a miscarriage, ectopic pregnancy, or fetal growth restriction.

See also

• Gestational age
• Pregnancy
• Ultrasound
• Fetal development

References

Crown-rump length Resources
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