what is crown rump length in pregnancy
An ultrasound showing a fetus measured to have a crown-rump length of 1.67 cm, and estimated to have a gestational age of 8 weeks and 1 day. Crown-rump length (CRL) is the 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.he length of the umbilical cord is approximately equal to the CRL throughout pregnancy. Gestational age is not the same as fertilization age. It takes about 14 days from the first day of the last menstrual period for conception to take place and thus for the conceptus to form.