Hi Linh,
I use 4mm as my diameter and yes, I do perform valsalva with the colour Doppler on the pampiniform plexus veins.
I don’t use pulse Doppler.
I also don’t call it a varicocele if there is just a single vein lurking in the left hemiscrotum. For me there has to be a “nest” of vessels in the scrotum to call it a varicocele. The veins should not just be in the lower hemiscrotum adjacent to the epididymal tail , but should extend along the length of the testicle .
These are my personal thoughts and using these criteria prevents me from over-calling normal pam-uniform plexus veins , particularly in the left hemiscrotum as a “varicocele”
There is some literature that advocated strict measurement criteria as well as supine and erect scanning, however I have not adopted this in my clinical practice.
Steve