What to Know About Portal Vein Thrombosis (PVT)

Portal vein thrombosis is a blood clot in the hepatic portal vein, a major abdominal vein that runs from the bowel and other organs to the liver. It isn’t a common condition, only occurring in five in 10,000 people. It can happen at any age, and does not affect one sex more commonly than the other. In approximately one of three instances, the blockage is formed slowly, and the body is able to create secondary blood vessels, called collaterals, that can bypass the block. Surprisingly, unless a patient already has liver damage, PVT will not damage the liver itself. The damage is caused by a build up of blood in the other organs connected to the vein.

Symptoms

People with PVT often do not know that their hepatic portal vein is blocked until after it results in a serious medical emergency. The only early symptoms may be abdominal pain, nausea, or a fever, all of which can be easily explained away. It is not until the condition becomes more serious that most patients seek medical treatment.Later symptoms include vomiting blood and internal hemorrhaging, as the back-up blood causes smaller blood vessels leading to the vein to burst.

Causes

There are several possible causes of PVT. Damage to the liver is the most common cause. Cirrhosis, trauma or cancer in the liver or nearby areas of the abdomen can lead to this condition. Pancreatis can also cause a blockage. Clotting disorders and dehydration may also create a blood clot in the hepatic vein. Other possible causes include estrogen treatment, dehydration, malnutrition and sepsis.

Diagnosis and Treatment

Unless the blockage is discovered while scanning a nearby area, it is unlikely that this condition will be detected until it is in an advanced state. PVT is most often diagnosed through a ultra-sonogram, CAT scan or MRI. If the scan shows a blocked vein, a liver biopsy will be scheduled to diagnose this condition. Once PVT has been diagnosed, further testing will be required to determine the original cause.

As PVT is most often diagnosed due to bloody vomit or hemorrhaging, the first part of treatment is to treat the bleeding. The bleed will be stopped, often using banding or sclerotherapy, which is used to shrink blood vessels. Patients whose PVT is caused by a damaged liver will need a liver transplant. Anti-clotting medications will be used in minor or recent clots; older blockages will be bypassed by the surgical implantation of a shunt.

Prognosis

Over 75% of patients with portal vein thrombosis can expect to live longer than 10 years. Most make a full recovery, and live the rest of their lives without further problems. Unfortunately, the exceptions to this are patients with cancer, cirrhosis or other serious liver damage. It is essential that these patients get a liver transplant, and there may not be enough time to wait for an available donor liver.

References

Vein Directory: Portal Vein Thrombosis. Accessed from: https://www.veindirectory.org/glossary/2007/9/portal_vein_thrombosis.html

eMedicine: Portal Vein Obstruction. Accessed from: https://emedicine.medscape.com/article/182425-overview