Umbilical cord entanglement

Last revised by Travis Fahrenhorst-Jones on 16 Jun 2022

Umbilical cord entanglement is a feature which can mean either one or more loops of the umbilical cord encircling any part of the fetal body or two umbilical cords becoming entangled with each other 3. In the latter situation, it is a classical feature of a monochorionic-monoamniotic twin pregnancy.  Very rarely it can occur in a diamniotic twinning with disruption of the dividing membrane either naturally or secondary to a procedure such as an amniocentesis.

It is often considered a part of normal early fetal development and can be a common finding in the 1st trimester. It has been described in over 70% of MCMA twin pregnancies and it is less of a problem in very early pregnancy.

If an associated tightening/knot is a concern Doppler assessment can be carried out.

If there is problematic flow due to cord entanglement there may be evidence of abnormal RI's and S:D ratios, the presence of diastolic notching and reduction in end-diastolic flow in umbilical arterial Doppler assessment and pulsatile waveforms in umbilical venous flow assessment.

Cord entanglement itself is rarely a problem but an associated tightening leading to an umbilical cord knot is a concern where arterial compromise can cause catastrophic complications.

Considerations in ultrasound include

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Cases and figures

  • Case 1
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  • Case 2: around fetal limb
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