from Physics 101:  Pressure P = Flow Q  x  Resistance R

(mm of mercury and cm of water are different ways of measuring pressure)

 a search on Yahoo

Portal Hypertension - Pathogenesis
  Portal pressure can be defined by the equation P (portal pressure) = Q
(blood flow in the portal venous system) x R (hepatic
resistance). Any condition causing increased portal venous flow, or
increased hepatic resistance, can develop into portal
hypertension. In practice, most conditions associated with portal
hypertension are due to a combination of these 2 factors.
 -- from Hepatitis Central

PORTAL HYPERTENSION: a portal venous pressure greater than 20 mm Hg
associated with splenomegaly, increased collateral circulation,
varicosity, bleeding and ascites.
 -- from Definitions of Liver Diseases and Disorders - Hepatitis C Forum

see also,  Portal Hypertension - Hepatitis C Society of Canada

"... Radiological and nuclear medicine tests may
give clues as to the presence of cirrhosis, but the diagnosis of cirrhosis
must often be made by liver biopsy."

Another interesting article:
The Mechanism of Progression of Chronic Liver Disease:
                 Implications for Histological Grading and Staging
The accurate assessment of activity and architectural distortion in chronic
 liver disease requires knowledge of the lesions that lead to cirrhosis.

peter sam, web content developer
Primary Care Clinical Practice Guidelines'
[log in to unmask]  asian health services  818 webster oakland ca

On Tue, 21 Sep 1999 16:34:54 -0400, Carrico, Diane F.
<[log in to unmask]> wrote:

>I have a radiologist who is looking for the conversion factor that gives
>pressure inside the hepatic vein.  He remembers that the formula is: mm of
>mercury X cm of water but he doesn't recall the exact formula that's used.
>This factor is used to
>to determine cirrhosis of the liver.  I checked "Bockus Gastroenterology,"
>5th ed., and, "Sleisenger & Fordtran's Gastrointestinal and Liver Disease,"
>6th edition, but, the conversion factor wasn't mentioned.  The doctor said
>he saw this is a textbook long ago so it may not be used anymore.  Any help
>would be appreciated.