Diagnostic Ultrasound - Abdomen and Pelvis

Liver Transplant Portal Vein Stenosis/Thrombosis
IMAGING
• Portal vein stenosis
○ Elevated portal vein velocity > 125 cm/sec at
anastomosis
– Portal vein velocity normally < 60 cm/sec
○ Anastomotic to preanastomotic velocity ratio
– Stenosis: > 3
– Normal: ~ 1.5
• Portal vein thrombosis
○ No detectable flow in portal vein
○ May see echogenic thrombus in portal vein, or portal
vein may appear markedly hypoechoic or even anechoic
○ May see enlarged hepatic arteries
– Hepatic arteries compensate for portal vein
thrombosis due to hepatic arterial buffer response
○ Bidirectional low amplitude flow in portal vein may
precede portal vein thrombosis
KEY FACTS
PATHOLOGY
• Portal vein stenosis
○ Occurs at site of anastomosis
• Portal vein thrombosis
○ Associated with surgical technique
○ Hypercoagulable state
CLINICAL ISSUES
• Portal vein stenosis typically occurs at the anastomosis
• Depending on degree of stenosis, may require balloon
angioplasty
• In chronic or longstanding portal vein stenosis, may see
portal vein aneurysm downstream from anastomosis
• Portal vein stenosis and thrombosis are relatively rare,
occurring in 1-2.7% of liver transplants
Diagnoses: Liver
(Left) Graphic idepicts focal
stenosis ſt of the portal vein
at the level of the anastomosis
in a patient with a liver
transplant. (Right) Volumerendered
CT angiogram in a
patient with liver transplant
shows a focal caliber change
ſt in the portal vein at the
site of anastomosis, consistent
with stenosis.
(Left) Pulsed Doppler
evaluation of the main portal
vein near the anastomosis
shows a focal area of aliasing
ſt as well as corresponding
elevated velocities measured
to 181 cm/sec . (Right)
Pulsed Doppler interrogation
in the same patient in the
portal vein proximal to the
area of aliasing shows velocity
is in a normal range of 23
cm/sec ſt. Elevation of
velocity at the anastomosis of
> 3x the pre-anastomotic
velocity is highly suggestive of
stenosis in the portal vein.
http://radiologyebook.com/
275