Umbilical cord entanglement is a feature which can mean either one or more loops of the cord being encircled around any part of the fetal body 3 or two umbilical cords getting entangled with each other. 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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