Tip 73: antenatal umbilical artery Doppler

In normal pregnancy, there is a progressive increase in end-diastolic velocity due to growth and dilatation of the umbilical circulation. The resistance index therefore falls.

A resistance index >0.72 is outside the normal limits from 26/40 onwards.

In some pregnancies with IUGR and/or pre-eclampsia, there is a reduction in the diastolic velocity and in severe cases there is absent or reversed end diastolic velocity.

Dopplers

Reference: McCowan, L., 2001. Doppler Studies in High Risk Pregnancies. Guideline from Auckland and District Health Board: Neonatal Intensive Care.

 

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