Sinusoidal obstruction syndrome of the liver

[Sommer]

Sinusoidal obstruction syndrome of the liver is blockage of the very small (microscopic) veins in the liver.

Fluid tends to accumulate in the abdomen, the spleen may enlarge, and severe bleeding may occur in the esophagus.
The skin and whites of the eyes may turn yellow, and the abdomen may enlarge.
Doctors base the diagnosis on symptoms and results of Doppler ultrasonography.
If possible, the cause is corrected or eliminated, and symptoms are treated.

(See also Overview of Blood Vessel Disorders of the Liver.)
Sinusoidal obstruction syndrome is similar to Budd-Chiari syndrome except that blood flow is blocked only in very small blood vessels in the liver rather than in larger ones in the liver or in blood vessels outside the liver. That is, blockages do not affect the large hepatic veins and the inferior vena cava (the large vein that carries blood from the lower parts of the body, including the liver, to the heart).
Sinusoidal obstruction syndrome may occur at any age.
Because flow out of the liver is blocked, blood backs up in the liver. This backup (congestion) then reduces the amount of blood entering the liver. Liver cells are damaged because they do not get enough blood (ischemia). The congestion causes the liver to become engorged and enlarged. The congestion also causes increased pressure in the portal vein (portal hypertension). Portal hypertension can result in dilated, twisted (varicose) veins in the esophagus (esophageal varices). The elevated pressure in the portal vein and the liver congestion lead to fluid accumulating in the abdomen—called ascites. The spleen also tends to enlarge.
Such congestion reduces blood flow into the liver. The resulting liver damage leads eventually to severe scarring (cirrhosis).