#58673
Stephen Bird
Keymaster

Hi Abhijit,

For the pelvic venous congestion “nutcracker” of the left renal vein between the SMA and aorta:

I cover that topic in the scrotum webinar at one hour , four minutes in when I discuss varicoceles in men.

It is not a complete discussion, but something.

It is a topic I will get around to producing a specific webinar on eventually.

When I do one of these studies I have the patient lying on one of my beds that tilt, and then tilt the bed 60 – 70 degrees so they are reasonably upright, but still stable.

I start with the aorta / SMA interval and look for a nutcracker type compression of the left renal vein at this point.

I look for venous compression of the left renal vein between the SMA and aorta with the renal vein with the vein measuring less than 2mm in AP diameter (compressed.
Just to the left of the nutcracker measuring more than 10m,m in AP diameter (congested).
I look for a left renal vein PSV greater that 110cm/sec in the nutcracker. (stenosis)
I look for a left renal vein just to the left of the nutcracker PSV less than 15cm/sec (congested)

Then I scan out along the left renal vein (short axis to the vein so I am in a sagittal scan plane), look for the left gonadal vein draining into the left renal vein. The gonadal vein will be in long axis. Doppler assess it here and without Valsalva it will be flowing retrograde with the patient moderately erect. You can Valsalva if you need to.

Then try and identify the right gonadal vein draining directly into the IVC below the level of the SMA / left renal vein location you have just been looking at.
Do the same test on the left gonadal vein. In some patients I cannot identify the left gonadal vein as it is small and normal.

Assess the common ilia, internal and external iliac veins for flow direction. You may observe retrograde frow in the internal iliac vein. Again Valsalva is usually not required and the flow will be retrograde continuously.

In a male and female patients you can look in the right and more importantly left inguinal canal for venous engorgement. It is spectacular when you see it.

In females you can do a TV scan looking for venous engorgement of the uterus and adnexae.

In a male you can look for a varicocele.

I have attached a grading chart.

ALSO: there is some controversy about the nutcracker theory with some believing the tight space is an effect, not a cause.

What I mean by this is that the venous blood from the left kidney sees an easy path to flow into an incompetent left gonadal vein and hence the lack of flow in the renal vein by the time it passes posterior to the SMA means it collapses and looks like it is being crushed. If you put the patient head down trandelenberg the space opens back up as gravity no longer makes it easy for the left renal venous blood to pour down the gonadal vein!!

It is a great debate, and I have tried it on a few patients where the gap opens beautifully once they are head down.

Food for thought!

Always keep questioning the stuff you were taught years ago and just assumed must be correct !!

As for May Thurner: I have only ever diagnosed it when I am presented with a spontaneous left iliac thrombus that is unexpected.

In a patient without a clot I think an intravenous ultrasound using a catheter gives a good look at the vessel wall for thickness and fibrosis changes that make the diagnosis.
I am no help scanning through the skin.

If anyone has some tips on this I am all ears,

Please chime in !

Steve

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