Fetal pole

Fetal pole

The fetal pole is an early stage of human development, which is observed in the pregnant uterus via ultrasound. It is the first visible sign of the embryo in the gestational sac. The fetal pole appears as a thick area alongside the yolk sac, which later forms into the baby.

Development

The fetal pole is seen during the fifth week of gestation. It is the first structure that can be recognized as the developing fetus. The fetal pole grows at a rate of about 1 mm a day, starting at the 6th week of gestational age.

Measurement

The length of the fetal pole is used to determine the gestational age of the pregnancy and predict the due date. This measurement, known as the crown-rump length (CRL), is used up until the end of the first trimester. After this point, other measurements are used as the fetus becomes too large to accurately measure CRL.

Clinical significance

The absence of a fetal pole in an ultrasound scan may indicate a problem with the pregnancy. This could be due to a miscarriage, an ectopic pregnancy, or a molar pregnancy. If no fetal pole is detected, further tests may be required to confirm the viability of the pregnancy.

See also

• Gestational sac
• Yolk sac
• Embryo
• Crown-rump length