Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

Sinusoidal Obstruction Syndrome of the Liver

(Veno-Occlusive Disease)


Whitney Jackson

, MD, University of Colorado School of Medicine

Reviewed/Revised Jan 2022 | Modified Sep 2022
Topic Resources

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.

Sinusoidal obstruction syndrome is similar to Budd-Chiari syndrome Budd-Chiari Syndrome Budd-Chiari syndrome is caused by blood clots that completely or partially block blood flow from the liver. The blockage may occur anywhere from the small and large veins that carry blood from... read more 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 Portal hypertension is abnormally high blood pressure in the portal vein (the large vein that brings blood from the intestine to the liver) and its branches. Cirrhosis (scarring that distorts... read more ). Portal hypertension can result in dilated, twisted (varicose) veins in the esophagus (esophageal varices Gastrointestinal Bleeding Bleeding may occur anywhere along the digestive (gastrointestinal or GI) tract, from the mouth to the anus. Blood may be easily seen by the naked eye (overt), or blood may be present in amounts... read more Gastrointestinal Bleeding ). The elevated pressure in the portal vein and the liver congestion lead to fluid accumulating in the abdomen—called ascites Ascites Ascites is the accumulation of protein-containing (ascitic) fluid within the abdomen. Many disorders can cause ascites, but the most common is high blood pressure in the veins that bring blood... read more . The spleen also tends to enlarge.

Did You Know...

  • Some herbal teas can cause sinusoidal obstruction syndrome of the liver.

Blood Supply of the Liver

Blood Supply of the Liver

Causes of Sinusoidal Obstruction Syndrome

Common causes include the following:

Symptoms of Sinusoidal Obstruction Syndrome

Symptoms may begin suddenly. The liver enlarges and becomes tender. The abdomen may swell because of fluid accumulating there. The skin and the whites of the eyes may become yellow—a condition called jaundice Jaundice in Adults In jaundice, the skin and whites of the eyes look yellow. Jaundice occurs when there is too much bilirubin (a yellow pigment) in the blood—a condition called hyperbilirubinemia. (See also Overview... read more Jaundice in Adults .

Diagnosis of Sinusoidal Obstruction Syndrome

  • A doctor's evaluation

  • Liver blood tests and blood-clotting tests

  • Ultrasonography or invasive tests

Doctors suspect sinusoidal obstruction syndrome based on symptoms or blood test results that suggest liver dysfunction, particularly if people have ingested substances or have conditions that may cause the disease (particularly people who have had a bone marrow or stem cell transplant). Blood tests, if they have not already been done, are done to determine how well the liver is functioning and whether it is damaged (liver tests Liver Blood Tests Liver tests are blood tests that represent a noninvasive way to screen for the presence of liver disease (for example, viral hepatitis in donated blood) and to measure the severity and progress... read more ) and to evaluate blood clotting.

Doppler ultrasonography Doppler ultrasonography Ultrasonography is a type of medical imaging that uses high-frequency sound (ultrasound) waves to produce images of internal organs and other tissues. During an ultrasound, a device called a... read more Doppler ultrasonography often confirms the diagnosis. Occasionally, invasive tests are necessary. These tests include liver biopsy or measurement of blood pressure in the hepatic veins and portal vein. To measure blood pressure in these veins, doctors insert a catheter into a vein in the neck (jugular vein) and thread it to the hepatic veins. A liver biopsy Biopsy of the Liver Doctors can obtain a sample of liver tissue during exploratory surgery, but more often they obtain a sample by inserting a hollow needle through the person's skin and into the liver. This type... read more can be done at the same time.

Prognosis of Sinusoidal Obstruction Syndrome

The prognosis depends on how extensive the damage is and whether the condition causing it reoccurs or continues—for example, when people continue to drink senecio tea.

If the cause is an ingested substance, stopping its use helps prevent further liver damage.

Treatment of Sinusoidal Obstruction Syndrome

  • Treatment of cause

  • Treatment of problems resulting from blocked vessels

There is no specific treatment for the blockage. If possible, the cause should be eliminated or treated. For example, if people are consuming a substance (such as an herbal tea) or taking a drug that can damage the liver, it should be stopped.

Ursodeoxycholic acid helps prevent sinusoidal obstruction syndrome from developing after bone marrow or stem cell transplantation Stem Cell Transplantation Stem cell transplantation is the removal of stem cells (undifferentiated cells) from a healthy person and their injection into someone who has a serious blood disorder. (See also Overview of... read more . Sinusoidal obstruction syndrome due to graft-versus host disease may be treated by increasing the dose of drugs used to suppress the immune system or defibrotide sodium.

Problems resulting from the blocked vessels are treated. For example, a low-salt (low-sodium) diet and diuretics help keep fluid from accumulating in the abdomen.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Cyclophosphamide, Cytoxan, Neosar
Azasan, Imuran
quiz link

Test your knowledge

Take a Quiz!