Topics

Topic

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Umbilical cord

The umbilical cord is a vital structure of fetal development, connecting the fetus to the placenta and enabling maternal-fetal exchange. It typically measures about 50–60 cm in length and 1.5–2.0 cm in diameter at term. The cord contains two umbilical arteries and one umbilical vein, all embedded in protective Wharton’s jelly and enclosed by the amniotic membrane.

The umbilical cord ensures transport of oxygenated blood and nutrients from the placenta to the fetus and returns deoxygenated blood and waste products back to the placenta.

Synonyms

  • Funiculus umbilicalis

  • Navel string (historical)

  • Umbilical funis

Structure

  • Umbilical vein: Single, large vessel carrying oxygenated, nutrient-rich blood from placenta to fetus

  • Umbilical arteries (2): Smaller paired vessels carrying deoxygenated blood and waste products from fetus to placenta

  • Wharton’s jelly: Gelatinous connective tissue surrounding vessels, protecting them from compression or kinking

  • Covering membrane: Amnion forms a smooth outer layer around the cord

Relations

  • Fetal end: Inserts into the fetal umbilicus

  • Placental end: Attaches to the fetal surface of the placenta, usually central but may be eccentric or marginal

  • Surrounded throughout by amniotic fluid in the amniotic sac

Function

  • Provides vascular connection between fetus and placenta

  • Supplies oxygenated blood and nutrients to fetus via umbilical vein

  • Removes carbon dioxide and waste via umbilical arteries

  • Cushioned by Wharton’s jelly to prevent vessel collapse

  • Allows fetal mobility without compromising circulation

Clinical Significance

  • Single umbilical artery: Associated with congenital anomalies and intrauterine growth restriction

  • Cord prolapse: Cord slips through cervix, compromising fetal circulation

  • Cord knots/strangulation: Can cause fetal distress or demise

  • Velamentous insertion: Cord inserts into membranes rather than placental disc, increasing risk of vessel rupture

  • Nuchal cord: Cord wrapped around fetal neck, may complicate delivery

  • Imaging: MRI used when ultrasound findings are unclear, especially in complex pregnancies

MRI Appearance

T2 HASTE (T2 GRE):

  • Umbilical vessels appear as flow voids (dark circular/linear structures)

  • Wharton’s jelly: intermediate  signal

  • Surrounding amniotic fluid: bright hyperintense, providing natural contrast for cord visualization

T1 GRE:

  • Umbilical cord overall: low-to-intermediate signal intensity

  • Umbilical vein and arteries: low signal flow voids

  • Wharton’s jelly: usually intermediate signal

  • Hemorrhage or thrombosis (if present): may appear bright hyperintense

MRI image

Umbilical cord MRI axial anatomy image-img-00000-00000

MRI image

Umbilical cord mri coronal image