Portal Vein

What is the portal vein?

Your portal vein is a blood vessel that carries blood from many organs in your abdomen (belly) to your liver. Your liver filters and processes this blood before it returns to your heart and recirculates through your body.

Usually, veins carry blood toward your heart rather than to other organs. Your hepatic portal system (portal venous system) is an exception to this rule. The veins in this system send blood to your liver, rather than directly to your heart. Your portal vein is the main blood vessel in this system. To understand your portal vein and its job, it helps to learn a bit about your portal venous system.

Portal venous system

Your portal venous system is a network of veins that drain blood from the following organs in your belly:

• Small intestine.
• Large intestine.
• Stomach.
• Pancreas.
• Spleen.
• Gallbladder.

Numerous smaller veins in your portal venous system collect blood from all of these organs and deliver it to your portal vein. You can think of your portal vein as a pit lane at a racetrack. It leads to your liver, which serves as a pit stop for your blood to receive necessary maintenance.

By the time blood reaches your portal vein, it’s full of nutrients that need processing before your body can use them. This blood also contains toxins, or harmful substances your body doesn’t need. Your liver “tunes up” your blood by converting nutrients to forms your body can use right away or store. It also removes toxins from your blood.

After this tune-up, your blood is ready to go back to your heart. So, it leaves your liver and travels to your inferior vena cava, which delivers blood to the top right chamber of your heart (right atrium).

What is the function of the portal vein?

Your portal vein delivers blood from organs in your belly to your liver for processing. Therefore, it’s vital to your portal venous system. It’s the main passageway for blood to enter your liver. All the other veins in your hepatic portal system ultimately converge (join paths) and lead to your portal vein. So, it needs to be healthy and working at its best for the whole system to work as it should.

Tributaries of the portal vein

Your portal vein has several tributaries, or veins that drain into it. These include your:

• Superior mesenteric vein, which drains several organs in the middle of your belly, including your small intestine.
• Splenic vein, which drains your spleen.
• Inferior mesenteric vein, which drains portions of your large intestine.
• Gastric veins, which drain your stomach.
• Cystic veins, which drain your gallbladder.

Where is the portal vein located?

Your portal vein begins just behind the neck of your pancreas and in front of your inferior vena cava. It extends to your porta hepatis (liver hilum). This is an opening in your liver that allows blood vessels and other structures to enter and leave your liver.

What is the anatomy of the portal vein?

Your portal vein forms at the point where your superior mesenteric vein (SMV) and splenic vein meet. From there, your portal vein travels upward and toward the right, behind your hepatic artery, until it reaches your liver.

As it enters your liver hilum, your portal vein splits into two branches. These are your left portal vein and right portal vein. These branches further divide into additional branches that travel to different parts of your liver.

Variations in anatomy

The most common anatomical variation is portal vein trifurcation. This is when your portal vein splits into three branches, rather than two, as it enters your hilum. In this case, the branches are the:

• Left portal vein.
• Right anterior portal vein.
• Right posterior portal vein.

This variation isn’t dangerous, but your healthcare provider needs to know about it before performing some surgeries and procedures. Providers run imaging tests prior to surgery to learn your anatomy and adjust techniques as needed.

How big is the portal vein?

Your portal vein is typically 8 centimeters (cm) long and no more than 13 millimeters (mm) wide.

What conditions can affect the portal vein?

Conditions that can affect your portal vein include:

• Portal hypertension. This is elevated blood pressure in your portal vein and its branches. It’s a serious complication of cirrhosis of the liver.
• Portal vein thrombosis. A blood clot narrows or blocks your portal vein or one of its branches. This condition typically affects people who have cirrhosis of the liver or a blood clotting disorder.

Common tests to check portal vein health

If your healthcare provider suspects problems with your portal vein, they may order one or more of the following tests:

• Comprehensive metabolic panel (CMP) to check your liver and kidney function.
• Complete blood count (CBC) to look for causes of portal hypertension or internal bleeding.
• Ultrasound to check blood flow through your portal venous system.
• Upper endoscopy to look for signs of gastrointestinal (GI) bleeding, a complication of portal hypertension.

Common treatments

Your provider will recommend the best treatment for you based on the test results. Treatment varies widely based on the underlying problem. It may include one or more of the following:

• Medications.
• Minimally invasive procedures.
• Surgery.

Your provider is the best person to talk to about treatment options in your specific situation.

How can I keep my portal vein healthy?

There’s a lot you can do to keep your portal vein healthy. The first step, though, involves talking with your healthcare provider. Ask if you have any risk factors for portal vein problems and what you can do to lower your risk.

Some general tips include:

• Manage underlying conditions. Conditions like metabolic syndrome can damage your organs and blood vessels. Talk to your provider about how to manage any conditions. You may need to take medication or make lifestyle changes.
• Follow a heart-healthy diet. Eating plans like the Mediterranean Diet support the health of your circulatory system. Like a network of pipes, your blood vessels connect to one another throughout your body. Changes to your diet can help keep the whole system healthy, including the veins of your liver.
• Exercise. Follow your provider’s guidance on developing an exercise plan that’s right for you. It’s also important to add more movement to your day whenever possible. This might mean parking farther away from the door or taking the steps instead of the elevator. Moving around improves blood flow through your body.
• Keep up with your appointments. Visit your provider for yearly checkups and keep all of your follow-up appointments. Doing so can help your provider diagnose and treat conditions early.

What is the hepatic portal vein?

Your hepatic portal vein is another name for your portal vein. Most people simply call it your portal vein, but you might see “hepatic portal vein” in some medical sources. Both terms refer to the same blood vessel. “Hepatic” means something is related to your liver.

It can be easy to confuse your hepatic portal vein with your hepatic veins. Your hepatic veins (without the word “portal” in the name) are a set of three veins that drain blood from your liver into your inferior vena cava. So, while your hepatic portal vein sends blood into your liver, your hepatic veins carry blood out of it.

A note from Cleveland Clinic

Learning the anatomy of your blood vessels can help you understand your body on a whole new level. You might be learning about your portal vein due to a medical diagnosis. Or, maybe someone you know has a condition that affects this vein.

No matter how you came to the topic, remember that learning is a lifelong process. All the different names and anatomical locations can be a lot to take in. Just learn a little bit at a time and ask your healthcare provider to explain more. The knowledge you gain can help you talk to your provider about your condition or a loved one’s condition. This shared vocabulary can be empowering as you make sense of diagnoses, treatment plans and the path ahead.