What do the mesenteric veins do?

There are two mesenteric veins – the superior and inferior mesenteric veins. The mesenteric veins drain blood from the intestines, carrying it into the portal vein so nutrients can be processed by the liver.

What happens if a mesenteric vein is blocked?

A clot in the mesenteric veins can reduce blood supply to the intestines. If the blood flow is completely blocked, the intestines may not get enough oxygen. This can cause tissue death in the intestines (bowel infarction), which is serious and requires urgent medical attention.

What symptoms can this cause?

There may not be any symptoms of mesenteric vein thrombosis. However, it can cause symptoms such as abdominal pain, which is often severe, persistent, and gets worse after eating. Other possible symptoms include nausea, vomiting, diarrhoea and bloating. In more severe cases, this can lead to tissue death in parts of the intestine, which can cause symptoms like blood in your stools and fever, requiring urgent medical attention.

How can a blood clot in the mesenteric vein be treated?

Blood thinners are the main treatment to dissolve the clot and reduce the risk of further clotting. In severe cases, where part of the intestine has been damaged, surgery may be needed to remove the affected section.

What does the splenic vein do?

The splenic vein drains blood from the spleen, pancreas, and parts of the stomach, directing it into the portal vein and towards the liver.

What happens if the splenic vein is blocked?

A clot in the splenic vein – which is called splenic vein thrombosis – can cause blood to back up in the spleen, making it bigger (splenomegaly). This can lead to low blood cell counts due to increased breakdown of blood cells in the swollen spleen. It can also cause varices (enlarged veins) in the abdomen, which may bleed.

What symptoms can this cause?

There may not be any symptoms of splenic vein thrombosis. However, it can cause abdominal pain, particularly in the upper left side of the abdomen, due to spleen enlargement (splenomegaly). Another symptom includes feeling full sooner than usual when eating. In some cases, splenic vein thrombosis can lead to low platelet counts or anaemia. If varices (enlarged veins) have formed in the abdomen, these can sometimes bleed. Symptoms of this can include vomiting blood or black, tarry stools. It is important to seek medical attention straight away if this happens.

How can a blood clot in the splenic vein be treated?

If there are no major symptoms, treatment may not be needed. However, blood thinners can help prevent clot growth. If enlarged veins in the abdomen (varices) develop and they bleed, medications or procedures may be required to stop the bleeding.

What does the portal vein do?

The portal vein is a blood vessel that carries nutrient-rich blood from the digestive system to the liver. After you eat, your stomach and intestines absorb nutrients from food. Unusually, instead of sending this blood straight to the heart, the body first directs it through the portal vein to the liver. The liver then processes these nutrients, removes toxins, and helps regulate blood sugar levels before the blood continues on to the rest of the body.

What happens if the portal vein is blocked?

If a clot forms in the portal vein – a condition called portal vein thrombosis – it can partially or completely block blood flow to the liver. This can lead to a buildup of pressure in the veins around the digestive system, causing problems like swelling in the spleen and the development of enlarged veins (varices) in the stomach or oesophagus, which can sometimes bleed.

What symptoms can this cause?

Symptoms vary depending on how severe the blockage is and how quickly the clot forms. Some people have no symptoms, while others may experience stomach pain, bloating, nausea, or a swollen abdomen due to fluid buildup (ascites). Rarely, portal vein thrombosis can cause tissue death in the intestine, which requires urgent medical attention. If varices (enlarged veins) have formed, these can sometimes bleed. Symptoms of this can include vomiting blood or black, tarry stools. It is important to seek medical attention straight away if this happens.

How can a blood clot in the portal vein be treated?

Treatment depends on how severe the clot is. Blood thinners (anticoagulants) are often used to prevent the clot from getting bigger or to reduce the risk of new ones forming. If bleeding occurs, doctors may use medications, special procedures, or even surgery to stop it. In some cases, procedures to improve blood flow, such as placing a small tube (a stent) in the vein, may be needed. The goal is to manage symptoms, prevent complications, and restore normal blood flow as much as possible.

What does the hepatic vein do?

The hepatic veins carry filtered blood away from the liver and back to the heart. After you eat, your stomach and intestines absorb nutrients from food. Instead of sending this blood straight to the heart, the body first directs it through the liver. After the liver has processed nutrients and removed toxins in the blood, the cleaned blood flows through the hepatic veins to the heart and into the main circulation.

What happens if the hepatic vein is blocked?

A clot in the hepatic vein – a condition called Hepatic Vein Thrombosis or Budd-Chiari Syndrome – can cause blood to back up in the liver, leading to liver swelling and damage. If severe, it can lead to liver failure.

What symptoms can this cause?

Hepatic vein thrombosis can cause symptoms like abdominal pain (especially in the upper right side), a swollen abdomen due to fluid buildup (ascites), nausea, yellowing of the skin (jaundice), and swollen legs. It is important to seek medical attention if this happens.

How can a blood clot in the hepatic vein be treated?

Blood thinners (anticoagulants) can help prevent the clot from growing or reduce the risk of new clots forming. In severe cases, procedures to improve blood flow – such as inserting a small tube (a stent) in the vein, or even a liver transplant – may be needed.