Hi Samuel,
Lovely to hear from you again,
Increasing the intra-abdominal pressure is essential for identification and assessment of inguinal and femoral hernias. There are many methods people use to produce a valsalva effect. Many like yourself ask the patient to cough and this works well but it is not my favourite. The problem I have with a cough is that it can be too “violent” and short. I ask the patient to put their thumb on their lips and pretend they are blowing ups balloon. I can then ask them to blow harder or softer and ask them to keep blowing and then to stop when I choose. This gives me great control with a pressure graded valsalva that is long enough to observe the hernia movement.
In normal patients without a hernia there is a variety of structures that can move slightly within the canal. Many people have a tongue of pre-peritoneal (extraperitoneal) fat in the canal. This moves with valsalva but the deep ring does not distend and no pain is caused. They can also have a cord lipoma which is an island of fat within the canal that can not be reduced from the canal and there is no posterior wall defect nor fat coming through the deep ring.
There is also the pampiniform plexus drainage veins which dilate with valsalva.
As for 3D/4D and contrast articles I have only limited experience.
In Australia in the private system ultrasound contrastt is not used as it is not financially supported by our Medicare government funding.
A sonographer and friend in New Zealand Martin Necas is the guru of contrast and I will ask him for some references for you.
3D and 4D we do perform mainly for gynaecology and foetal abnormalities like club foot, craniofacial, limb and spine deformities.
Let me know what you are interested in and I will forward you some material.
We don’t find 3D / 4D useful in other areas and in the MSK arena it is a fancy toy but never really changes the diagnosis or the way we think about the case.
My measure of useful technology is to ask the question ” If I use the new technology does it change the diagnosis or provide extra insight that will change my worksheet or the patient management” The challenge for 3D / 4D , contrast, elastography etc is to pass this test and then I think it has proven benefit.
All of these technologies have found some niche uses where this is the case but many applications are simply restating what we know.
Let me know what applications you have in mind and I will continue this discussion,
Steve