I have a question about using duplex US to identify and localize
congenital arterio-venous malformations.  I have had a few cases through
the years, and have not really had much luck with tracking the little
devils down.  I have been able to predict a couple of intracranial cases
based on the differences between the flow signals in the two carotid
arteries.  But in the extremities, as on the child I saw today with
hugely distended veins and even small venous ulcerations on his left
leg, they have remained elusive.  I looked at the entire arterial system
for low resistance or turbulence;  I looked at the entire venous system
for arterialized flow, pulsation, etc.  And found nothing.  No
difference compared to the same site on the unaffected right leg.  I
looked at iliacs and all the way down the leg.  I tried to just look for
abnormal color flow.  I looked with velocity scale set high.  Set low.
Gain up, down etc. Nothing.

Have others had more success than I have?  I feel like I must be
overlooking something.
Thanks!   Norma V.